nm0217: okay think we've probably got a quorum [0.3] er [1.8] we [0.3] er we're 
going to be recorded for posterity today [0.2] 
ss: oh 
nm0217: do you want to say do you want to say something about what you're doing 
[0.7] do you mind 
om0218: yeah [0.2] er well [0.8] i'm working at CALS which is next door Centre 
for Applied Studies and and we [0.6] work with international students who [0.2] 
entering the university [0.4] trying to help them to prepare for [0.5] 
listening to lectures and writing [0.7] er assignments and so on [0.6] and i'm 
going round the university collecting recordings of lectures [0.3] in different 
departments so that i can have a look at the kinds of [0.5] language that's 
used [0.3] in lectures [0.7] so then we hope we can improve our teaching 
[laughter] [0.9] 
nm0217: yeah so we're going to be recorded for posterity on a C-D i think is it 
[0.5] 
om0218: a minidisc [0.2] yes 
nm0217: wow [0.2] 
sf0219: ooh 
nm0217: technology [0.4] so if any of you want to shout out Judas in the middle 
of the lecture [laughter] Bob Dylan fans would only understand that one [0.3] 
[laughter] [1.2] er it's quite ironic 'cause i got [0.6] er [0.2] at the end 
of the firs-, the student response for the first year module [1.0] i did last 
term i got four-point- [0.2] seven out of five for audibility of voice when i 
told my wife this she said she thought i was making it up 'cause she said i 
mumble all the time [1.2] it's usually when i she says things like oh isn't it 
about time you painted that window sill with all the little teeth marks in i 
say yeah all right [laughter] [1.0] so er anyway [0.5] i'll try and be fairly 
er [0.9] audible today [1.4] er [0.6] this also means that if there's anything 
we don't want to appear on the tape i can write it on the board and er 
[laughter] [1.2] and see [0.3] er now there's a slight change to the programme 
like the video i was going to show you today i lent to a student who of course 
hasn't returned it on time despite several reminders [0.4] so er i'll have to 
show it to you er what i'll probably do is to you in week nine [0.6] er when 
we've got tho-, [0.3] in week nine [0.3] on the timetable we've got debate 
preparation [0.8] on that day i've got to give two lectures to the first years 
which i won't finish till eleven [0.8] so what i'll probably do is have a have 
a meeting [0.4] say for half an hour at eleven o'clock to discuss the debate [0.
2] the following week [0.8] and then er i'll show you the video which is about 
forty-five minutes [0.5] so we'll do that in week nine so what i've done 
instead today is i've picked out some more [0.6] er slides so at the end of the 
two lectures today we're going to have [0.7] er a couple of dozen slides to 
back up some of the things i'm going to talk about [1.3] now we're going to do 
er th-, th-, in fact we're going to do three topics today [1.6] er [0.5] before 
the coffee break i'm going to talk about pesticides [0.5] and then after the 
coffee break [0.9] i'm going to [0.9] cover [0.2] er introduce you to the 
concepts of risk assessment as they're used in environmental management [1.0] 
and also in human [0.6] health as well [0.4] with special emphasis on the mad 
cow disease epidemic and its possible [0.7] er the possible numbers of people 
who are going to be affected by [0.6] er the human variant of mad cow disease 
which as you'll see from the 
handout [0.4] could be anything from [0.3] a hundred to several thousand [0.7] 
the data at the moment isn't [0.2] isn't concrete enough to make an accurate 
prediction [1.3] and then i'm going to say something briefly about 
ecotoxicology which is the way in which we can try and [0.5] assess the 
environmental effects of chemicals [0.4] before they're released into the 
environment using standard [0.5] test animals [0.4] but i'll go into that in a 
lot more detail after the break [1.8] okay so [0.5] first of all we're going to 
look at [1.1] er the c-, [1.7] couple of pesticides with obviously an 
environmental [2.3] emphasis [2.3] now [0.5] th-, th-, the most important thing 
to b-, bear in mind throughout the lecture really is [0.5] pest is a human 
definition [0.8] and a pest is simply a plant [0.7] or an animal which is 
living where man [0.4] doesn't want it to live [7.1] er and the best example i 
like to use of this is er is moles [1.1] er i quite like moles i think they're 
quite cuddly cute little animals but of course they're considered to be a pest 
and it's quite legal to poison them and trap them [0.7] 
things like bats which i think are ugly [0.5] little blighters [laughter] [0.6] 
er have enormous protection and if you [0.2] have bats in your loft bats in 
your belfry even [0.4] you it's illegal to disturb them even if they're filling 
the [0.4] the void of your loft space up with er [0.3] bat droppings [0.6] and 
you can't [0.2] you can't disturb them and it's simply a er human perception of 
moles [0.9] are not good and bats are good [1.0] and er i saw this thing which 
has quite amused me which was er [0.8] i'll put this back up in a second [0.6] 
which was another thing from the innovations report [0.8] er and it's a thing 
called the sonic [0.6] mole chaser [0.2] the idea is that it's an 
environmentally friendly [1.5] way of getting rid of moles [1.1] it says these 
[0.3] what you do is you ram this thing into the ground [0.5] and it le-, [0.3] 
lets off a low frequency vibration and this annoys the moles and they move away 
[0.7] [cough] and there's a little [0.7] cartoon here of a mole disappearing 
presumably into next door's garden [0.8] it says [laughter] these sil-, these 
silent and unobtrusive repellents [0.5] are a humane way of persuading 
moles to leave the area [0.7] it's recommended by the Northern the widely read 
Northern Gardener magazine [0.3] [laughter] [0.4] but the best one i heard was 
a er it was on the Gardeners' Question Time on the radio where apparently you 
[0.9] if you want to get rid of moles what you do is you buy one of these 
Christmas cards or birthday cards that when you open it up it plays 
Greensleeves or something [0.5] you take the little [0.3] musical [0.2] chip 
out of it [0.7] these last for about three months apparently and you drop them 
down the hole [0.7] and the moles get so annoyed [1.5] or [3.0] [laughter] that 
er [laughter] that er [0.7] [laughter] that they they go into next door's 
garden and these things [laughter] last for about three months [0.5] er and 
it's a sort of environmentally friendly way of er of getting rid of moles 
[laughter] [0.4] and then [0.2] three months later you just buy another one [2.
3] right now then er it might surprise you to know [0.2] that [1.2] most 
pesticides have not been developed [0.8] to [0.8] kill off insects [1.0] and in 
fact the main thrust of the [0.7] of the G-M crops the genetically modified 
crops research [0.5] has been not [0.3] to develop 
plants that resist insects although of course that is part of the [0.4] 
research programme [0.8] the main development is to do with [0.5] the fact that 
most pesticides are used to kill off other plants [1.4] and just to give you an 
sm0221: sorry can you repeat it [0.5] 
nm0217: pardon 
sm0221: sorry can you repeat it [0.7] 
nm0217: which bit [0.7] 
sm0221: [0.5] 
nm0217: er [0.2] most 
sm0221: [0.3] 
nm0217: er genetically modified crops 
sm0221: thank you [2.6] 
nm0217: is that okay [0.8] 
sm0221: 
nm0217: the whole [laughter] sentence right 
sm0222: sentence [0.6] 
nm0217: er [1.9] research into genetically modified crops you might think it 
was main-, mainly to do with [0.4] developing crops that were resistant to 
insects 
sm0221: mm [0.5] 
nm0217: the main in p-, but in fact the main [0.2] t-, [0.2] er [1.3] traits 
that are being [0.6] selected for are resistance to herbicides [0.6] in plants 
[2.2] okay [1.1] 
sf0223: [1.5] 
nm0217: and [0.6] this is because in the U-K for example about eighty per cent 
[0.6] of pesticide usage is for herbicides [0.5] just for spraying for weeds [1.
0] and only about ten per cent is for fungicides and about ten per cent for 
insecticides and then a minor component [0.7] for killing off other things for 
example [0.5] pesticides for killing off rats of course are called rodenticides 
[0.5] and i think 
you've probably heard quite a lot about that in the course [0.2] already [1.6] 
er [0.4] for herbicides th-, [1.0] the usage is mainly to do with er direct 
drilling [0.2] where [0.5] in the past er historical past of course [0.3] 
farmers would have always ploughed their fields before they planted the crops 
to kill off the weeds [0.6] now they can spray the fields and kill off the 
weeds and then plant the seeds directly in the ground without having to [0.4] 
to plough the [0.2] plough the field and this saves them an enormous amount of 
money in labour [1.0] this is called direct drilling [1.0] er fungicides are 
used mainly for seed dressings [0.7] when you collect seeds from a crop [0.2] 
to store for the following year if you store them in a [0.3] in a barn or 
something they can go mouldy quite quickly so if you [0.2] cover the seeds in a 
very thin layer of [0.4] of fungicide [0.6] and this prevents them from going 
mouldy [0.3] this is the main use of fungicides [0.5] in the U-K [0.9] 
insecticides have a have a [0.5] much smaller usage [0.5] because there aren't 
any really major insect pests of 
crops [0.6] and we don't in the U-K we don't get things like locusts swarms [0.
4] er coming in [0.3] and it's only occasionally when you get things like 
Colorado beetles [0.3] which is on the handout that i gave you [0.4] arriving 
[0.3] that er tha-, that you have to very seriously spray for insect pests [0.
8] so that's the sort of ratio that er [0.5] of usage that you get [1.8] now 
the [0.3] ideal pest-killing chemical [0.6] if it existed [1.1] would [0.5] do 
the following [0.7] first of all it would only kill the target pest [3.5] so [0.
5] if you have a pest [0.9] problem [1.0] you want your pesticide to be very 
specific to only target the specific thing that you're trying to [0.3] kill off 
[1.5] of course as we know that's not [0.8] often er [0.3] invariably not the 
case [1.6] er [2.5] they should have no short [0.3] or long term health effects 
[0.9] on non-target organisms and this of course includes people [6.2] clearly 
you [0.5] preferably don't want to kill off the natural predators [1.0] of 
things so if you have had a [0.3] problem with [1.4] greenfly [0.3] er aphids 
on a crop [0.9] er clearly you don't want to kill off all the ladybirds because 
ladybirds eat lots 
of aphids lots of greenfly [1.0] but if you spray the crop to kill off the 
aphids then you'll kill off their natural predators as well [0.5] so the pest 
problem in the long term can in fact become worse [2.1] so ideally you'd want 
to target a specific er [0.5] specific organism that was causing the problem [3.
6] er the third [0.2] factor is you'd want them to break down rapidly into 
harmless components better rub this off while i remember hadn't i [0.4] 
[laughter] [2.4] break down into harmless components [0.6] so that you spray 
your [0.6] or you apply your chemical to the crop [0.4] it kills the pest [0.3] 
and then it breaks down very quickly [1.5] and er one as we'll see one of the 
problems of pesticides that were used s-, s-, historically in in the past [0.7] 
was that many of them were extremely persistent [0.9] you remember when we did 
the practical on D-D-T [0.3] the [0.3] D-D-T was shown to cause eggshell 
thinning [0.9] eggshell thinning in birds of prey [0.8] and i'll come back that 
to that in a bit more detail later on [0.7] but the pesticides which are being 
developed nowadays 
tend to have a much shorter half-life in the environment [0.6] and some of them 
will in fact break down instantly when they touch the soil [0.5] so er they're 
very effective [0.3] when you spray them but they break down very quickly so 
there aren't such long term [0.5] effects [1.3] a fourth er factor is quite 
important [0.7] although difficult to control [0.2] i mean i-, the ideal pe-, 
er pesticide should prevent [0.9] the development of genetic resistance to 
target [0.4] organisms [1.9] and i'll come back to this in more detail later on 
[0.8] 
but er [0.9] there are several species of insects which have become resistant 
[0.5] to a w-, a wide range of pesticides [0.5] and these are have very 
difficult to control [0.6] in the field without er [0.3] massive applications 
of pesticides which become ecologically [0.4] unacceptable [1.6] finally [0.2] 
er [0.4] farmers of course are all in in a business [0.2] as as we hear [0.7] i-
, increasingly nowadays [0.6] and the use of pesticides [0.4] should save money 
compared to making no effort to control pest species [2.8] and er pesticides 
are relatively have been relatively cheap [0.2] er and it's [0.3] in the farm-, 
[0.2] been in the farmer's interest to spray the crops very regularly [0.6] 
without actually [1.0] doing doing without the scientific back-up to to [0.7] 
er know whether or not this er is an an effective way of controlling the pests 
[1.4] sometimes you can get away with much fewer with with many fewer [0.3] 
applications of pesticides if you look for example at the climate [0.4] and the 
the weather conditions [0.3] and er th-, the natural population fluctuations of 
the pests rather than just spraying [0.4] say every [0.3] on the first Monday 
of every month [0.5] because your farmhand happens to have that allocated in 
his diary [0.6] look at the population structure of the pests [0.7] look at the 
weather [0.3] what's the best time to spray to have the most effective effect 
rather than just [0.7] er [1.3] spraying just because it happens to be that 
time of the month [2.3] okay now i want to say something very briefly about the 
different th-, the three main [1.3] types [1.0] of pesticide [1.5] just to 
illustrate the sort of [0.5] problems that you can have environmental problems 
that you can have [4.7] now [0.9] the most or [0.3] one of the most effective 
herbicides [0.2] that's a [0.2] pesticide for killing other plants [0.6] is a s-
, chemical called two-four-five-T [1.5] and this was very widely used in 
farming [1.0] and was also unfortunately very widely used in the Vietnam War [0.
2] where it became known as Agent 
Orange [1.1] and the American Army sprayed [0.5] er vast areas of the 
Vietnamese jungle [0.7] with two-four-five-T [0.8] er [0.3] in an attempt to 
actually wipe out the jungle completely so the Viet Cong [0.5] had nowhere to 
hide [1.4] couldn't hide in the jungle and l-, vast tracts of Vietnam were laid 
waste by the spraying of this chemical [0.8] and unfortunately during the 
manufacturing process [0.8] there's an impurity which [1.7] evolves [0.3] in 
the in the chemical process called dioxin and dioxin is extremely toxic [0.9] 
and [0.2] many of the American servicemen who were involved in spraying this 
chemical [0.4] and also farm workers who were spraying two-four-five-T [0.6] er 
[0.7] got some symptoms of dioxin poisoning [0.6] which is a general sort of er 
aching of the body aching of the limbs [0.4] er acne develops on the skin you 
get quite severe acne [0.6] er and eventually headaches er and er it can be 
quite dehabilitating [0.8] of course what happened to the [0.2] poor Vietnamese 
who were in the jungle [0.7] when they got sprayed i mean they've got very 
badly affected as well so er [0.6] the 
effects of dioxin [0.3] ca-, er have been quite serious [0.4] so one of the 
problems with [0.2] pesticides is that can contain impurities which cause 
effects [0.4] which are nothing to do with the [0.9] er th-, th-, the pest-
killing [0.7] status [2.0] er [0.3] for fungicides [0.5] there is an example [0.
3] quite a sev-, s-, er serious example [0.4] in Iraq in nineteen-seventy where 
[0.7] er seeds were dressed with mercury [0.2] it was quite common a common 
practice to dress seeds with mercury as a fungicide [1.0] ev-, even in the U-K 
up until er [0.3] the early nineteen-nineties it was still legal to do this no 
doubt now it's been stopped [1.5] but er in Iraq in nineteen-seventy [0.7] er 
the mercury which had been dressed s-, [0.3] w-, [0.3] ha-, was by mistake sent 
to a bakery [0.5] and er loads of bread were made out of this brea-, this these 
seeds [0.6] and er before it was discovered [0.7] er [0.3] that that this [0.9] 
had er had occurred er about a thousand people died of mercury poisoning [0.3] 
and many others were er [0.4] dehabilitated by the mercury [3.1] so you have to 
be very careful with these things with er that that that 
that they don't get [0.7] move in the wrong direction in the food chain [8.6] 
okay now thirdly [0.3] insecticides [1.9] er insecticides have been [0.6] again 
very widely [0.4] used and they're they've been studied quite intensively 
because of their potential effects on er high levels in the food chain [1.3] 
and [0.2] historically chemicals like D-D-T which were [0.3] developed [1.9] er 
[0.8] some some years ago now have have had a long half-life so [0.3] D-D-T 
technically has a half-life [0.5] of two-point-eight years [0.6] and [0.9] the 
ninety-five per cent breakdown [0.8] is about ten years [0.6] but er this can 
be much longer if [0.3] the D-D-T is in a [0.4] a cold environment or a dry 
environment [1.2] th-, the breakdown is very affecti-, er is very er affected 
by the temperature and the climatic conditions so these this is a sort of 
average figure [0.4] it can be much longer [0.5] now more modern insecticides 
like aldrin [0.5] er have a much shorter half-life [1.1] and they tend to break 
down more quickly and the very modern ones [0.2] will break down often in a 
period of days [1.6] and of course the 
problem with these insecticides is that they can accumulate in the food chain 
[0.7] now you don't need to copy this [0.2] down because you've had it on the 
er on the handout that i gave you for the practical but just to [0.6] er [1.0] 
reiterate again the problem about the eggshell thinning [1.3] the er D-D-T 
which was used very widely for sp-, for spraying crops [0.3] as an insecticide 
[0.6] was accumulated through the food chain [0.8] and er birds of prey like 
peregrine falcons and sparrow hawks which were eating [0.5] er [0.3] small 
small mammals and birds which had [0.3] accumulated D-D-T [0.7] [cough] became 
er badly affected because their [0.5] the D-D-T would [0.2] would interfere 
with the calcium metabolism of the birds [1.4] so if you remember from the 
practical when we measured the egg [0.2] eggshells [0.4] er i've just put up 
the peregrine falcon data [0.5] er we saw a thinning of the peregrine falcon [1.
0] eggs that had been removed from [0.3] abandoned nests [0.5] er in the sort 
of nineteen-fifties nineteen-sixties and there has quite been quite good 
recovery [0.5] er in recent years although we did still find a 
few eggs that were [0.3] were thinned [2.4] okay so [1.3] there can be 
impurities in these pesticides they can [0.7] get er into the human food chain 
if if you're not very careful [0.5] and the insecticides can also affect [0.3] 
things if they pass up through the food chain [1.9] now D-D-T it might interest 
you to know you'd think that D-D-T would have been banned but in fact this is 
an article from New Scientist [0.4] on the eighteenth of September [0.4] last 
year [0.8] and it says here proposals to ban the pesticide D-D-T by two-
thousand-and-seven [0.6] have been dropped [0.9] for fear of harming efforts to 
fight malaria [0.7] instead countries negotiating to limit persistent organic 
pollutants [0.5] agreed in Geneva last week to achieve elimination over time 
which is a good [0.2] politician's fudge phrase [0.5] on condition that poor 
countries get help [0.3] finding alternatives [1.3] er World Wide Fund [0.2] 
for Nature says combinations of safer insecticides bed nets and draining of 
mosquito breeding areas [0.2] control malaria just as well [0.7] but the World 
Wildlife Fund dropped calls for a ban by two-thousand-and-seven [0.4] because 
arguments over the date got in the way of the more important goal [0.4] of 
helping poor countries adopt alternatives [0.7] so [0.2] the proposal to ban D-
D-T by two-thousand-and-seven [1.1] has in fact been [1.3] dropped [0.9] so D-D-
T is still being used [0.4] in er developing countries [2.2] and of course if 
we have birds which er migrate [0.3] like the osprey which migrate from 
Scotland [0.6] down to er [0.8] to Africa [0.6] then they can pick up the D-D-T 
[0.2] when they're in Africa and then when they come back to the U-K and start 
laying eggs [0.5] that can cause problems [0.7] if the eggshells are thinned [2.
6] okay [0.5] so how are pesticides evolved there are three main generations of 
pesticides [0.4] the third of which has [0.7] arisen in the last few years [0.
7] but the first generation pesticides [0.3] pesticides have been around for a 
very long time [2.6] er [0.7] before nineteen-forty [0.5] which is a good sort 
of cut-off point [1.9] pesticides were [0.6] invariably natural products [3.7] 
and the pesticide pyrethrum [0.7] which is an extract from [0.3] er 
flowers of a [0.3] pyrethrum plant so you pick the [0.2] the flowers from the 
pyrethrum plant [0.7] er and they would be soaked in water and then you could 
spray that onto crops and the natural defence of the plant would also protect 
against insects [0.7] and there's evidence that the Chinese were doing this er 
two-thousand years ago so [0.4] many quite ancient cultures [0.5] have been 
using pesticides for [0.2] some considerable time [2.1] but er [1.1] s-, [0.2] 
just bef-, before and after the Second World War [0.2] there was a an explosion 
in the chemical industry er not an explosion [0.2] expansion [0.7] [laughter] 
in the chemi-, well probably was an explosion as well though w-, though i [0.3] 
talk about explosions later on [0.5] er there was a persistent [0.8] er th-, th-
, the persistent organ-, inorganic chemicals were developed [0.9] and it was 
thought at the time that er [0.6] in the sort of white heat of technology [0.7] 
that existed that er this was the answer to all pesticide problems [0.6] and 
that er if you had a pesticide problem you could just go and spray it with 
these chemicals and the problem would 
disappear [0.7] of course as we know that hasn't happened [3.1] er [0.5] some 
of the [0.2] chemicals which were used [1.3] in [0.5] in Victorian times [0.3] 
were quite toxic and in up to relatively recent times [0.8] er these include 
things like Bordeaux mixture [0.7] which is named after the [0.2] fact that it 
was used extensively for spraying vines in France [0.5] grape vines [0.8] and 
these are b-, [0.2] basically just solutions of of metal salts like copper [0.
4] and arsenic [2.0] and these are very persistent er and these would be 
sprayed on on [0.3] crops [0.6] and er [0.4] would be quite good at resisting 
[0.8] insect attack [1.6] er i always think it's ironic that if you go a garden 
centre and you go to the organic [0.4] sort of gardening section [0.7] they 
include [0.4] Bordeaux mixture as a traditional organic remedy which in fact 
it's [0.3] probably about the worst thing you could spray on your [0.5] on your 
garden because it is very persistent [0.7] and er if you analyse soil [0.5] 
from gardens and houses of more than [0.3] say before about nineteen-ten 
nineteen-twenty [0.6] they invariably have very high concentrations of [0.7] er 
copper 
and lead and arsenic because people would traditionally just use this Bordeaux 
mixture as a traditional remedy [0.7] er the house we used to live in off the 
Oxford Road in namex which was built in about nineteen-hundred [0.5] i analysed 
the soil [0.5] from from the back garden and it had about between five and ten 
times the normal background level of copper [0.6] and it's almost certainly 
because people had been spraying Bordeaux mixture [0.5] on their er on their 
roses or whatever they were growing there [0.7] at er the turn of the century 
[5.6] okay [4.4] now the second generation pesticides which have developed from 
the Second World War onwards are mainly synthetic [0.8] organic chemicals [0.9] 
so for example D-D-T came into [0.5] widespread use [0.5] from nineteen-thirty-
nine onwards [1.8] and er [0.6] it was a very [0.2] important er chemical it it 
its n-, [0.2] s-, it i-, er its use has certainly saved [0.7] er millions of 
lives [0.7] particularly for control in in wartime conditions where you get [0.
4] where you get high concentrations of people soldiers or refugees or [0.5] 
whatever people in very impoverished conditions or difficult [0.3] cramped 
conditions [0.4] you can get [0.2] diseases er [0.2] diseases like er typhoid 
[0.6] transmitted very easily and and [0.3] if you have [0.4] er mites [0.5] 
for example which or lice which are transmitting the diseases [0.7] er these 
were controlled quite effectively by D-D-T [0.8] and er this this er [0.2] had 
a big effect on er saving many a people's lives [0.4] 
particularly during the war [0.8] so although [0.2] these [0.2] chemicals 
clearly have have major problems environmentally they have saved a lot of lives 
[1.7] now worldwide [1.1] something like two-point-five-millions tons [0.6] of 
second generation pesticides [0.6] are used every year [0.8] so the massive [0.
5] massive quantities it's a huge er industry which is economically [0.9] is 
very important [0.9] but er eighty-five per cent of these are used [0.9] in the 
most developed countries like er America and [0.3] Western Europe [2.0] most 
farmers in developing countries [0.6] don't er use [1.1] as er pesticides [0.3] 
very [1.2] extensively because they're they're expensive [0.4] and er [1.0] 
there are cases of them being used [0.4] locally of course but er [0.2] in 
general [0.4] most of the pesticides are used [0.4] in developed countries [4.
3] er there are something like fifty-thousand different types of second 
generation pesticides [0.7] which have been developed [1.4] and of course this 
has [0.4] implicatio-, environmental implications because it's really would be 
impossible to test [0.7] every single [1.4] pesticide on every single potential 
species in the wild [0.6] and ways of getting around this problem i'll come 
back to later on when we [0.2] we talk about ecotoxicology after 
the break [0.7] so there are large numbers of of these chemicals [0.6] and the 
usage is more or less the same as it is in the U-K [1.6] about eighty-five per 
cent [0.5] of herbicides [0.2] o-, of c-, pesticides used in the world are 
herbicides [1.5] and of that eighty-five per cent about twenty-five per cent [0.
2] sorry twenty per cent is used on golf courses [0.4] and gardens [1.0] i read 
some statistic once that said that five per cent of all [0.6] herbicides in the 
world were sprayed on Japanese golf courses [0.8] and they just drench them 
with [0.4] chemicals to kill off the weeds [0.5] so they have this very very [0.
5] particularly on the golf greens [0.4] they have this very very pure er [0.3] 
grass [0.3] on a [0.5] on a specific [0.5] culture of grass which is mowed to 
within a couple of millimetres of the soil [0.6] so the golfers can [1.2] knock 
their balls in the holes [2.2] another reason reason for [0.4] banning golfers 
er [0.5] [laughter] [0.8] er [2.5] ten per cent are used er for insecticides [0.
8] and about five per cent for fungicides [1.5] so er [0.6] again we can see 
that the vast majority of chemicals are used for er [0.2] for herbicides [2.7] 
now [0.2] the third generation pesticides [0.7] which have come into [0.6] 
being in the last [0.8] few years of course are genetically modified [0.5] 
crops or G-M crops [3.3] and if i asked any people in this room whether they 
would eat genetically modified crops i would guess that most people would say 
no they wouldn't [0.9] and er the fact is that we've all eaten gemet-, 
genetically modified crops and we've been doing so for at least two or three 
years [0.7] and this is because [1.0] most of the soya [0.9] that's used [0.7] 
in er in food [0.3] processing for a very very wide range of things like [0.2] 
cakes [0.9] baked beans er [1.1] sauces er biscuits [0.4] tons of things [0.6] 
are made with the [0.2] h-, have soya added as a as a part of the food er [0.3] 
preparation process [0.6] and most of the soya that's used is now genetically 
modified soya [1.5] so we've all been eating it [0.8] er [0.3] whether or not 
we whether we like it or not [1.3] and the main thrust for the development of 
the genetically modified crops is to develop [1.5] crops which are resistant to 
herbicides [0.5] which may sound rather peculiar [1.6] but er the 
point of it is that if you can [0.5] make your crop resistant to herbicides 
then you can spray [0.3] er larger quantities of herbicides on a crop [0.5] you 
can make them grow faster because you can get r-, rid of the weeds more easily 
[0.6] er and this is because you cou-, if you for example if you spray twice as 
much herbicide [0.4] on a herbicide resistant crop [0.5] in theory you can get 
rid of the weeds twice as fast [0.5] because your genetically resistant crop is 
able to survive much higher doses of herbicide [0.9] this is very good for the 
[0.2] the manufacturers of herbicides because they can sell more [0.8] 
basically that's the that's the th-, idea behind the [0.4] the problem [1.4] 
and er on the handout one of the handouts i've given you this is er [0.8] er [1.
2] on the one about Colorado beetle i-, i'll come back to Colorado beetles 
later on [1.6] er the one that's on sideways on the bottom this is from 
yesterday's New Scientist so this this t-, course is nothing if not er topical 
[0.9] and er there's a little article here which says resistance is useless [0.
7] 
and it's confirmed that in fact the major fear [0.2] of the development of 
these herbicide resistant crops [0.5] is that the genes for resistance can pass 
from the crops to the weeds [1.2] if you then get [0.4] weeds which are [0.4] 
resistant to herbicides you can imagine the potential financial implications 
for farmers [0.9] because if you [0.7] er if you've got [0.4] er [0.4] weeds in 
a crop and you can no longer when you spray them with herbicides the weeds are 
no longer killed [0.6] it means that you might have to go back to the er [0.7] 
to a traditional method of farming [0.2] again which is [0.2] of course might 
be quite good but er [0.7] but er has enormous economic implications [3.7] now 
er in in America [0.3] there well let's just [0.3] do this where are we [0.3] 
properly [0.2] here we are [0.9] if we look at er [0.8] a couple of recent 
articles this is one from [1.7] this is from Nature back in November [0.6] this 
says er area under transgenic crops [0.2] shoots up forty-four per cent [1.4] 
it's the area of land planted with [0.2] G-M crops is expected to increase 
dramatically [0.3] particularly in China Argentina 
Canada and South Africa [0.4] according to Monsanto the U-S [0.5] agri-
biotechnology company [1.0] er the [0.2] company [0.4] said that almost forty-
million hectares [0.4] will be planted with G-M crops this year so we're not 
talking about a sort of fringe industry this has become a major thing [1.0] er 
says [0.4] G-M crops were planted commercially in Portugal and the Ukraine for 
the first time this year [0.9] Teng was speaking at the Asian rice [0.3] 
conference in the Philippines [0.9] [laugh] [0.5] so er [0.8] worldwide these 
things are really taking off er but in the U-K [0.5] er there is b-, a hol-, 
the British government has put a hold on it [0.8] er there's a cartoon down 
here it looks like President Reagan actually i'm not sure as to who is it 
supposed to be but er [laugh] [0.6] it says all we ask for is a level playing 
field [0.7] with a r-, roller with genetically modified crops [0.2] written on 
it squashing a [0.5] squashing a butterfly [0.9] er [0.4] so [0.2] the [0.4] 
implication is that the the the the companies who develop these things [0.5] 
are roller-coasting this thing through [1.3] but as i said in the U-K there is 
now a 
voluntary ban [0.6] on growing ge-, genetically modified crops in Britain until 
two-thousand-and-two [1.3] so er [0.6] that's that's been put on hold [0.3] in 
the U-K but in the rest of the world it's it's really taking off [0.3] and in 
America [0.6] er more than half [0.4] of of the acrea-, of the [0.2] of the 
area [0.4] growing certain c-, types of crops like er cotton for example are 
now genetically modified [0.5] at least they include genes to make them 
resistant to [0.4] to insects or resistant to herbicides [2.0] okay now er [0.
8] what i thought i'd do next was to go through the major types of insecticides 
[2.7] because er if you're reading around this subject which hopefully you you 
will er you'll come across these terms and it's useful to have the definitions 
in one [0.6] place [4.3] okay now the major types of insecticides [0.8] are 
there's four main types there's [0.3] first of all chlorinated hydrocarbons [3.
6] and er examples of these are D-D-T [0.6] and aldrin they're also known as er 
[0.5] organochlorines of course [0.8] and the persistence of chlorinated 
hydrocarbons [0.8] is quite high [0.5] up to 
fifteen years or more [9.9] okay the second type of insecticides are 
organophosphates [1.4] we're sort of going through a sequence of of development 
here in terms of the [0.3] t-, [0.3] historically how they developed [1.5] the 
the second type of insecticides are organophosphates and an example of an 
organophosphate is malathion [1.0] and these are tend to be l-, [0.2] these 
tend to be less persistent [1.1] up to er [1.3] to a year or so [0.3] de-, 
again depending on the [0.2] the sort of climatic conditions [1.5] and then th-,
the final two [1.0] have low persistence [0.4] carbamates [1.0] er [1.1] an 
example of which is carbaryl [0.7] has a low persistence typically of weeks [1.
0] and pyrethroids [0.9] again have a low [0.6] persistence of days or weeks [2.
1] but er py-, most of the pyrethroids that are used now [0.4] in farming are 
synthetic pyrethroids [0.7] and er one of the ways in which these insecticides 
have been developed [0.8] is that scientists have looked at the [0.5] chemical 
structure the molecular structure [0.6] of naturally occurring [0.4] chemicals 
like pyrethrum [0.7] and they have then synthesized a molecule 
which is very very similar but then th-, they've tweaked it to make it more 
toxic [0.9] so what they did with the synthetic pyrethroids was to look at the 
chemical structure of pyrethrum which is a chemic-, a naturally occurring 
chemical [0.6] in pyrethrum flowers [0.5] [cough] [0.7] synthesize it [0.4] er 
[0.3] synthesize it in the laboratory [0.5] and then change [0.2] change the 
structure of or slightly or maybe add or take off a hydrogen atom or something 
[0.6] er and then test this and ma-, er to to find whether it's more toxic [1.
3] 
and the commercially available synthetic pyrethroids [0.4] are more [0.2] toxic 
[0.4] to ins-, more toxic to insects than a naturally occurring [0.5] pyrethrum 
[0.8] t-, 
sf0223: change the [0.5] 
nm0217: yeah 
sf0223: does that mean they can then patent it [1.0] 
nm0217: er y-, er yes [1.1] yes so then most of these chemicals are patented [0.
9] that's why there probably why there's fifty-thousand [0.5] 'cause what they 
tend to do is they'll produce [1.0] you know if they come up with a new 
chemical in the lab [0.4] th-, er they might not have e-, any evidence that 
it's useful but if they patent it [0.4] in ten years time 
sf0223: yeah 
nm0217: [0.5] or at the end of the [0.2] field 
trials they might find that it's useful [0.4] 'cause these things take [0.5] 
typically new chemicals nowadays and drugs as well take about ten years [0.3] 
from [0.6] discovery to final commercial approval [0.4] because they have to go 
through a wide range of [0.9] of er tests [0.7] before they do that [2.3] 
sf0224: with things like the chlorinated hydrocarbons and you say they're [0.4] 
persistent can't you alter the persistence 
nm0217: yeah that's what these these more [0.4] well [1.0] organochlorines tend 
to be very stable molecules [0.5] because of [0.6] the the nature of the [0.4] 
atoms 
sf0224: 
nm0217: [0.3] yeah you and and it's difficult too [0.4] that's why these new 
chemicals have been [1.0] have been developed which are less [1.2] persistent 
[0.6] organochlorines in general are [0.3] persistent chemicals just 'cause of 
the nature of the [0.8] of the structure [0.3] the of the chemical [0.2] 
they're diffi-, more difficult to break down [3.9] okay now the major types of 
herbicides are three [0.7] main types of these [3.0] er first of all [0.4] 
contact [0.3] herbicides [1.6] an example of which is atrazine [2.1] and these 
things you spray them on the crops and they will kill the foliage [1.1] er 
because they block photosynthesis [12.0] er second type of 
herbicides you get are sys-, so-called systemic [1.2] herbicides and this is 
what [0.3] two-four-five-T is it's a sys-, systemic [1.0] herbicide [5.1] and 
the systemic herbicides interfere with the [0.5] natural hormones in the plants 
[1.2] and essentially they make them grow too fast [1.0] so [0.8] the plants 
can't take in enough nutrients [0.6] from the or water from the soil [0.6] to 
make to sus-, sustain the very rapid growth rates that [0.3] that they [0.4] 
that are induced by the spraying of these chemicals [3.4] and the third type [1.
0] are [1.4] things called soil sterilants [3.1] an example of which is 
trifluralin [0.8] and this [0.4] these chemicals will kill soil microbes 
essential for plant growth [0.9] so if plants have mycorrhizal [0.9] er fungi 
around the roots [0.5] or if they're nitrogen-fixing [0.9] for example [0.5] 
these soil sterilants will kill off these [0.2] microbes and the plants won't 
grow so well because they don't have this er symbiotic [0.3] these [0.3] 
symbiotic [0.4] fungi or microbes [0.6] around the roots [3.8] so those are the 
main [0.4] the main types [11.3] okay now [0.4] pesticides i've [0.4] given 
them a [0.2] pretty bad press [0.9] so far [2.0] but 
er of course pesticides can be [0.5] are are have been very useful [1.4] in a 
wide range of situations and if we just [0.6] present the case for the defence 
for a s-, for a moment [0.7] for a moment before we get on to the problems [0.
6] er pesticides have clearly saved [1.2] er millions of lives [0.6] 
controlling diseases [2.3] er for example malaria the spraying of pesticides 
managed to [0.7] ho-, [0.7] con-, con-, contain [0.6] m-, er malaria outbreaks 
quite successfully [0.6] for er a number of years [1.8] unfortunately we'll 
come we'll come back to this later but unfortunately of course er mosquitoes 
have m-, [0.3] become resistant [0.2] resistant to many of the pesticides that 
are used [0.5] and in some ar-, areas malaria has [0.3] returned [0.5] er 
because of this resistance [1.2] er the second [0.6] point is that [0.6] 
pesticides have [0.7] er increased food production [1.5] er lots of er er [0.2] 
crops have been saved by the spraying of pesticides because they would 
otherwise have been eaten by insects [0.6] er and it's estimi-, estimated that 
worldwide [0.7] about er fifty per cent of all crops [0.3] are lost to pests [2.
6] er 
incidentally another [0.2] another twenty-five per cent is thrown away [1.5] so 
of of the food which is grown [1.6] in the world [1.0] only about twenty-five 
per cent of it [0.8] actually ends up in a inside us [0.2] inside humans [2.0] 
one of my ex er [0.3] PhD students [0.4] namex [0.4] who er [0.9] left a few 
years ago went to work for Tesco's because he w-, [0.5] he realized that if he 
wanted his w-, he wanted a Porsche [0.5] and he realized that if he stayed in 
academic life there was absolutely no chance [0.7] and er [0.6] so he went to 
work for Tesco's he's now in the working in the office which plans new Tesco's 
[0.2] stores which is quite interesting [0.7] anyway he was [0.2] for a while 
when he was on the management training course [0.5] they put him in charge of 
the fresh fruit department in Tesco's in Broadmead in Bristol [0.2] which he 
said was like working in a [0.5] prisoner of war camp or something he said it 
was just unbelievably stressful [0.5] er for about eighteen months just to sort 
of test him out to make sure he could [0.3] could hack it [0.5] before they put 
him into the office and he said 
that they used to throw away about half of the f-, [0.4] half of the fresh [0.
3] produce was thrown away [1.2] only half of it was sold because things like 
tomatoes particularly [0.4] more than half of the tomatoes [0.4] that you see 
on the display that people pick out by themselves are thrown away because they 
s-, [0.2] go past their sell-by date [0.5] [cough] or because people damage 
them when they're handling them [0.6] so [0.2] on average about half of the 
food that's grown is lost to pests and of that that s-, [0.2] survives about 
half of it [0.6] is thrown away [0.3] which is [1.0] not good news really but 
er [2.4] okay [1.1] now one of the er [0.5] major problems with using 
pesticides of course is the development of genetic resistance [1.5] and [0.2] 
something like five-hundred insect species are resistant [0.7] to some 
insecticides [1.3] and [0.6] twenty insect species are resistant to some extent 
to all [0.6] insecticides [4.2] and this is a a clearly is a major problem [0.
6] er to to to put it into context [1.0] er in the U-K there are periodically 
there are outbreaks of er [0.6] scratching my head i shouldn't do that [0.3] 
outbreaks of head lice [0.4] instinctively scratching [1.3] and er my children 
had it a couple of times when they were er [0.6] you know when they were at sc-,
[0.2] school when they were about er [0.2] think once when they were about six 
and once when they were about er [0.3] ten [1.1] er haven't had it for a quite 
a long time i should reassure you about that but er [laugh] [0.7] so i don't 
have it now but er it's very widespread and you very often er [0.5] friends of 
ours who've got children will often mention oh there was an outbreak of head 
lice at school today [0.5] and head lice [0.4] has [0.5] re-emerged in the last 
[0.9] fifteen t-, [0.3] ten to fifteen years [0.5] as a p-, as a problem [0.7] 
and this is because the head lice have become resistant to the chemicals that 
are used [0.4] in their control [1.3] and er when our kids had head lice you 
have to go to [0.3] to Boots the chemists and er buy some [0.5] head lice 
lotion and you rub it some of you probably know about this who probably don't 
want to admit it but [0.6] you have to rub it in your hair and leave it for a 
[1.0] er half an hour or something 
then you wash it all out and then you have to do it the same thing again a week 
later to kill off the eggs or anything that's hatched out [1.0] and er what 
they do in Boots [0.3] o-, in all the chemists is there is a national programme 
to [0.3] change the [0.6] active ingredient in this shampoo [0.5] er about 
every month or two [0.7] and the idea behind it is to prevent the head lice 
from becoming resistant to one particular chemical [1.0] so for one month they 
may use er malathion [0.8] as the active ingredient and then a couple of months 
later they'll change from malathion to another chemical [0.6] and the idea is 
to prevent the head lice from becoming resistant to [0.8] to er [0.7] to these 
insecticides [0.9] 
the er the nowad-, [0.3] in the last year or two [0.4] head lice have become 
resistant to all the chemicals that have been used and it's now become very 
difficult to get rid of them [0.6] and er people are recommending that you go 
back to the traditional methods [0.4] of of [0.6] of er combing with a very 
fine comb [0.4] on a regular basis to try and get rid of them but it's not [0.
5] nothing like as effective as dousing them with [0.6] chemicals [0.5] so head 
lice is a is a [0.2] m-, [0.4] major problem at the moment [2.3] another 
problem with pesticides of course is that you tend to kill off natural enemies 
[1.7] if you spray a crop you'll kill off things like ladybirds and er [1.3] 
fly larvae that are eating eating things [1.4] and of course er you can kill 
off [0.9] er [1.4] wildlife [3.7] and there are [0.2] clearly threats to er [0.
2] to wildlife if you're spraying a crop particularly on a windy day [1.2] less 
than ten per cent of the [0.3] pesticide that you spray will settle on the crop 
most of it will get [0.3] land on the soil or will get 
blown away [0.5] to adjacent [0.3] er land and if of course if you've got 
farming surrounding a nature reserve [0.6] it's possible that you could get 
quite severe mortality of [0.5] of er insects [0.9] if the pesticide blows on 
to the nature reserve [2.2] and of course there are threats [0.4] [cough] 
excuse me to wildlife and humans through passage up through the food chain [3.
1] er f-, [0.4] last of all the problems er you do get occasionally get major 
disasters the worst one that's occurred is the explosion which i [0.4] referred 
to earlier on [0.7] and this was at a place called Bhopal [0.7] a Union Carbide 
factory in India [1.2] and here three-thousand-three-hundred people were killed 
[0.7] by release of thirty-six tons of [0.6] methyl [0.4] isocyanate gas [1.5] 
this is in nineteen-eighty-four [0.5] and about twenty-thousand serious 
injuries occurred [0.5] so [0.5] er you you can get major disasters that [0.4] 
in with the chemical industry [0.2] associated with [1.1] er leakages of [0.4] 
toxic chemicals [9.9] of course cyanide is also in the news at the moment 
because of this there's a been a major [0.3] release of 
cyanide from a gold [0.5] mine in Romania [0.2] and it's [0.4] seems to have 
killed almost everything in the Danube [0.8] in the last week or two [6.2] okay 
[0.9] now [1.0] before we go on to look at a few slides [2.9] what are 
alternative methods of pest control without using chemicals [7.4] okay now the 
first of these is is [0.3] biological control [2.8] and with biological control 
[0.5] you can encourage the na-, p-, [0.3] instead of just spraying [0.3] the 
pests you can encourage natural predators [0.6] to try and bring the pests 
under control [0.8] er for example you can now commercially buy little packets 
of [0.3] of eggs of [0.2] parasitic wasps [0.6] which you can hang up among 
crops [0.5] and when these hatch out these will parasitize the pests [0.7] 
particularly er aphids [1.6] and er they lay eggs inside the p-, the aphids and 
the aphids [0.2] die because the larvae eat [0.2] eat them [1.1] eat them from 
the inside out [2.2] but these [0.9] methods really only work very well in 
glass houses where you can [0.3] p-, [0.2] where you can confine the [0.5] pest 
and the [0.3] predator [0.2] or the parasite [0.7] if you try it in the field 
[0.4] the 
the the the the the density of the parasites isn't sufficiently high [0.3] to 
control the pest because they tend to fly away [0.6] so that works pretty well 
[0.8] in er in glasshouses [1.9] course you can also introduce [0.6] diseases 
[0.8] into [0.9] pests [1.3] er particularly virus diseases [0.7] and this can 
also be ef-, [0.2] effective [2.6] and there's a thing called bacillo virus 
which is [0.5] quite widely used commercially as a pesticide which contains a 
bacterial toxin [0.9] which will [0.7] kill off [0.6] insect pests particularly 
[0.2] caterpillars [3.8] now [0.2] another [0.2] way which is quite a cunning 
way and this is a good example of where basic biological knowledge [0.2] 
zoological knowledge is used [0.5] in an applied sense [0.7] and this is what's 
called insa-, insect sterilization [0.7] and this has been quite effective in 
controlling a pest [0.2] rather disgusting pest [0.4] called the screw worm fly 
[0.8] in America [0.7] this fly lays its eggs on the back of a [0.4] back of a 
cow [0.6] and the larvae hatch out and then burrow through the skin of the cow 
and live in a sort of chamber underneath with a breathing 
hole [0.2] it's a revolting [1.0] sty-, lifestyle [0.6] really [0.5] and er and 
this apart from causing intense irritation to the cow [0.7] er means that you 
can't sell the hide afterwards 'cause it's full of holes [1.2] and what they do 
here is they will [0.3] breed [0.7] screw worm flies in the lab [1.2] they [0.
2] expose them to irradiation and this sterilizes them [0.3] so you end up with 
large numbers of sterile male flies [1.2] er you then release [0.4] thousands 
and thousands of these sterile flies into the field [0.6] and they will mate 
with the females and of course because they're sterile the females' eggs are 
not fertilized [0.6] and er when the females come to lay the eggs there are no 
larvae to hatch out [0.6] and although this doesn't get rid of the problem 
completely it reduces it to such a low level that it becomes commercially 
viable [0.7] er and is is a very good way of controlling the [0.5] the pests [2.
2] now another way is to attract [1.8] pests [0.5] u-, er sort of hijacking 
their natural [1.1] s-, er [1.0] attractive attract [0.2] er sexual attractant 
system [1.7] and of course many species of moths [0.6] er the 
males will be attracted to the females because the females give off this 
pheromone [0.3] sort of come and get me [0.2] chemical [0.7] and what you can 
do is you can either [0.2] you you can have a [0.5] in the field you can have a 
[0.2] you know like those er [1.2] ultraviolet traps you get in butchers' shops 
and things and food shops with a [0.6] ultraviolet light and an an electrified 
grille [0.9] and the fly comes in and sort of oh there's a ultraviolet light 
and then go she-oo pssh whack [0.2] zap you hear this crack as the thing gets 
[0.4] instantly electrocuted well you can do the same thing with moths and you 
can put a [0.5] a female moth behind one of these grilles [0.6] and the males 
come flying in thinking thinking they're about to have sex and then they [0.6] 
whack zap they get [0.2] electrocuted on the electric grille [laughter] [0.7] 
and er of course [0.2] one female can attract [0.2] hundreds thousands of males 
[0.5] and er this is very effective at reducing the [0.5] the er incidence of 
males in the population [0.6] and can ha-, kind of be quite effective [1.3] now 
there was something again in yesterday's 
New Scientist which is [0.6] er [0.4] very similar to this [0.7] if you read 
the article [0.3] you'll get it in more detail but the Colorado beetle which is 
a major [0.3] pest [0.3] of potatoes [1.2] er they're suggesting er using the 
same technique but rather than using a sex attractant [0.4] to find out what 
the active smell is in potato leaves [0.6] and er again use this as a as a trap 
mechanism you put the [0.3] the chemicals in a trap [0.8] and er the Colorado 
beetles think oh it's a potato [0.5] and they come [0.3] flying in [0.4] to the 
er to the trap and then of course they get killed because er [0.4] because 
they're er [1.8] 'cause it's not a potato a-, at all it's just a chemical to 
attract them [2.0] 
and er f-, finally insect hormones [1.8] er [1.0] you can mess up the 
biochemistry of [0.2] insects by spraying them with chemicals which mimic [0.3] 
chemicals within their bodies [1.2] er within [1.4] ca-, er caterpillars for 
example [0.4] there's a cormone called juvenile hormone [1.4] and the animals 
secrete juvenile hormone [0.5] until the end of the fifth instar [0.6] and then 
it the juvenile hormone [0.5] production stops and then they then pupate [0.2] 
into a pupa and then of course into a butterfly or a moth [1.7] if you [0.3] 
spray the insects with these juvenile hormones or or mimics of the juvenile 
hormone synthetic versions of these hormones [0.5] you can prevent the 
caterpillar from pupating [1.1] so it gets to the fi-, fifth instar and then it 
just keeps growing [0.3] moults into a sixth instar and eventually it will die 
because er [0.5] because the other [0.7] components of its biology [0.7] think 
it's [0.3] turning into a pupa when it's 
still a still a caterpillar [0.7] so you can [0.3] er [0.4] target the 
pesticides to [0.4] hit particular aspects of the biochemistry of the animal [3.
2] okay [0.3] right final [1.1] overhead before we er look at some slides [6.2] 
whoops [3.4] okay now this is a schematic [0.3] er [0.4] diagram [0.2] don't 
want to er show you that yet [1.2] schematic diagram which illustrates the 
principle of biological [0.3] pest control [1.0] if we have time along the X-
axis and pest density along the Y-axis [1.0] the purple line [0.7] is the 
density of the pest [0.7] and the orange line is the economic threshold [0.9] 
if we can get the population of the pest [0.5] well below the economic 
threshold [0.6] then er [0.2] then it's [0.4] if there's a small amount of pest 
damage it doesn't really matter if the dif-, if the overall [2.5] level of 
damage is acceptable [2.2] so if you've got the pest [0.5] density going along 
here it's clearly t-, [0.3] above the economic threshold line which is [0.4] 
too high [0.6] er [0.6] if we introduce some method of biological control [0.6] 
some of the methods which we er [1.4] mentioned above [1.8] we can get the pest 
population to get down below the economic 
threshold [4.5] and [0.2] this means that we have to accept a small amount of 
pest damage [0.5] but the damage is not sufficiently great to significantly 
affect the the income [0.9] of the farmer [3.7] but [0.4] if we do biological 
control we have to accept some damage i'm giving away my age here but er [1.5] 
most of you probably haven't heard of Joni mitch-, Joni Mitchell but there's a 
song that you hear ev-, every so often Big Yellow Taxi and [0.4] one of the 
lines is [0.5] give me spots on my apples but leave me the birds and the bees 
[0.9] and er every time if you go shopping in the supermarket and you're 
picking out apples for example from a [0.4] a big display of apples [0.5] if 
you pick one up and it's got a small imperfection on it [0.5] a hole or a small 
scab or something [0.4] if you put it back you're encouraging [0.5] the over-
use of pesticides because you are only accepting perfect fruit [0.7] and the 
environmental consequences of perfect [0.4] fruit and vegetables [0.4] is an 
increased use of pesticides [0.7] so er [0.4] we have to if we want to use 
less pesticides and [0.7] use biologic-, [0.5] biological control [0.2] we have 
to be able to accept [0.5] that er some of the things that we eat may not be er 
absolutely perfect [8.3] okay [0.7] let's look at some slides before we stop 
[42.7] right [1.0] has everybody finished with this [2.1] yep [3.3] okay [0.2] 
about another ten minutes or so then you can have a [0.5] 
sm0225: really [0.7] 
nm0217: [laughter] what's s who said all right [laughter] [0.6] can have a nice 
er [1.0] er a coffee break [4.2] right [0.7] now then er of course pests as i 
said aren't just used for killing [0.5] insects [1.7] er [0.5] this is a [0.4] 
Forestry Commission [0.4] plantation just south of Reading at a place called 
Heath Warren near Bramshill [1.1] and [0.2] when they [0.4] clear the trees 
when they chop down the trees as a commercial product [1.3] er what's left 
behind is er [0.2] is a [0.2] bare ground because the light doesn't penetrate 
very well here and you get a very rapid growth of things like birch trees and 
er general [0.8] er low [0.2] growing plants [0.8] and they can control these 
by spraying [1.0] and this is just an example here this is the [0.5] an area 
which has been felled [0.9] and after they've felled it er they put this notice 
up i've got a [0.5] higher magnification picture of it here [0.5] here we are 
[1.3] er this is a [0.6] this area has been sprayed to control weeds [0.7] and 
there's a [0.5] says herbicide applied do not eat fruit [0.2] and there's a pi-,
just in case you don't know what [0.3] fruit looks like there's a [laughter] 
picture of it [0.8] and er if you were a kid and you had an I Spy book [0.4] I 
Spy Signs [0.2] that would probably be worth about two-hundred marks [laughter] 
'cause it's a [0.6] 'cause it's a [0.6] couple of blackberries with a line 
through [0.5] so er [0.7] they spray the area instead of [0.2] going around for 
somebody physically going around and chopping all this stuff down [0.4] it's 
obviously much cheaper [0.2] for them to spray [0.4] spray it er to allow the 
baby [0.5] pine trees [0.5] the chance to grow up because if they don't do that 
then the pine trees get er [0.3] get smothered by this very rapid growing [0.5] 
er vegetation [2.8] now er one method of biological control [0.3] is to 
encourage [1.6] natural predators of pests to [0.8] migrate into crops [0.2] 
and in [0.4] some farms nowadays the farmers will leave a strip quite a 
wide strip around the field [0.5] and this acts as a reservoir for things like 
carabid beetles and er natural predators [0.8] and during the night they can 
crawl from this area this refuge into the crop [0.5] and er help to control the 
pests [0.9] it's not a er a complete substitute for spraying [0.6] but 
certainly it has been shown that there are significantly lower numbers of pests 
[0.4] in the margins of these fields than there are [0.4] in the centre [0.4] 
and what th-, some of them [0.3] er [0.2] very organic farms [0.3] do is they 
will put strips of these sort of set-aside strips [0.5] right through the crop 
[0.5] er so that the [0.2] natural predators have a refuge all throughout the 
crop and this does significantly reduce the [0.5] incidence of pests [2.9] okay 
now just something briefly about the D-D-T problem [1.6] er the D-D-T didn't 
didn't just affect birds of prey this is a [0.8] picture of a a nest of a brown 
pelican [0.7] and this is a [0.4] double-crested cormorant [0.7] which [0.2] 
became deformed in the egg the egg managed to hatch but as it grew [0.5] this 
the beak was very badly 
deformed [0.5] you can see the upper part of the beak here is curled [1.6] and 
here the eggs have become squashed by the female because the eggshells have 
become thin because of the interference with the calcium [0.2] and metabolism 
by the D-D-T that was used in the area [2.5] in the U-K [0.6] er this is [0.3] 
changes in the status of sparrow hawks in relation to agricultural land use [0.
9] this is a proportion of land which is farmed [0.3] er [1.0] intensively and 
you can see the black areas here in East Anglia particularly [0.4] of very 
intensive farming [0.7] and this is the er populations of sparrow hawks [0.9] 
around the time when D-D-T was being used [0.9] and you can see there's an 
almost mirror image here in the [0.2] in the terms of the intensity of farming 
[0.5] and the populations of sparrow hawks [0.3] sparrow hawks manage to [0.7] 
er persist qu-, in quite high populations in Wales and south-west England where 
the farming intensity is lowest [0.9] but er during the maximum period of usage 
of D-D-T the sparrow hawks died out almost completely [0.4] from East Anglia [0.
3] 
although now of course they've returned [2.4] and er this illustrates the [0.5] 
whole problem this is the [0.7] same thing with peregrine [0.3] falcons [0.6] 
relative to nineteen-thirty you can see that the population of peregrines 
declined [0.6] during the usage [0.9] of er s-, these pesticides [1.2] and has 
recovered [0.3] quite substantially since [2.2] the er [1.1] D-D-T was in fact 
banned throughout the E-, European Community f-, in nineteen-eighty-one 
although in the U-K it was banned [0.6] banned earlier [1.0] than that [3.0] 
and this is the eggshell thickness index er just reiterates [0.4] what we saw 
on the overhead and we saw in the practical class that there was a distinct 
thinning [0.8] during the period of maximum [0.5] D-D-T use [1.7] and that er 
if we relate the thickness of eggshells [0.5] to the D-D-E content which is the 
[0.9] er [0.7] er metabolic breakdown [0.3] product of D-D-T [0.6] we can see 
there's a very clear correlation [0.7] between the thickness of the eggshell [0.
2] and the concentration [0.5] of D-D-E [4.8] okay [0.6] so now i just want to 
show some general slides to back up the [1.1] idea of 
pests [0.8] er this is [0.4] over in chemistry this is the where the manic mole 
used to er [laugh] [0.7] do its stuff there's a big [0.2] huge ar-, there's 
this big area of daffodils which are about to come out now [0.7] but er [0.2] 
every so often the mole manages to get across the road and then it causes all 
these little er [0.4] little hummocks [0.4] but again it's a [0.3] the concept 
to the fact that the moles are a pest because they're in an area that er [0.4] 
the ground staff don't want them to be so they [0.3] they're defined as a pest 
[0.6] whereas if they were a t-, colony of bats [0.4] living in the [0.3] top 
of the er Chemistry department up here then we wouldn't be able to do anything 
about it because they'd be legally [0.4] protected even though they might be 
covering the floor in [0.2] er bat droppings [0.5] [laugh] [2.4] okay here's 
some more pests this is a [1.0] er an example where you can have a an animal 
which has a natural [1.8] its natural food er is a plant which grows wild in 
the environment but er if it manages to cross that barrier and start eating 
other plants then it becomes a serious 
pest this is a large white butterfly caterpillar [0.4] which of course is a 
very [0.3] er severe pest of cabbages [0.3] but it will s-, will also eat 
nasturtiums this is a one on a nasturtium leaf [0.5] in our back garden [0.5] 
so these things can cres-, pests can cross [0.4] er species barriers and eat [0.
4] er [0.3] plants which they wouldn't naturally have evolved to [0.7] here's 
another pest this is a sawfly larvae [0.3] this is a larvae of a of a wasp 
rather than a moth or a butterfly [1.6] and if you don't know the difference 
between them the way to tell the difference between a sawfly larvae and a [0.6] 
caterpillar a butterfly or moth is that sawflies have seven [0.7] pairs of 
prolegs one two three four five six seven [0.6] as opposed to [0.3] butterflies 
and moths which have five [1.7] but er these sawfly larvae are quite serious 
pests of u-, of a range of crops [0.5] and er [0.3] when you annoy them they 
will [0.5] exhibit this characteristic alarm behaviour which is to raise their 
bottoms in the air and er [1.0] apparently it's supposed to to scare off er [0.
2] potential [0.6] attackers [1.5] 
okay er greenfly this is a [1.6] w-, one of the main problems with aphids is 
that they can reproduce very rapidly and [0.3] they can reproduce 
parthenogenetically [0.5] which means that [0.3] they don't have to have males 
[0.5] the females can produce [0.5] baby greenflies little baby greenfly here 
[0.2] aren't they sweet 
sf0226: mm 
nm0217: [laughter] [0.7] er without without mating with a male so they can 
increase their population [0.3] density extremely rapidly [1.4] er 
exponentially in fact er [0.6] in under certain circumstances [0.4] and of 
course if you spray the crops then you'll kill off [0.5] the natural predators 
of [0.5] of these things like two-spot and seven-spot ladybirds [0.5] these 
here are munching their way through some [0.5] er cherry aphids on a cherry er 
[0.2] cherry tree in our b-, [0.2] again in our back garden at home [1.1] so 
they a ladybird can eat [0.4] between fifty and eighty greenfly a day so they 
really are major er [0.4] pests er [0.2] major predators of pests [2.4] here's 
another one this is a hoverfly larvae [1.2] er sorry not a hoverfly larvae a 
lacewing larvae [0.3] eating a eating a fly here and these again are major 
pests 
of er [0.6] pred-, predators of of of pests particularly greenfly [0.9] and 
here's one here this is a business end here which has [1.4] grabbed on to this 
this er fly [2.4] so all these things will get killed if you spray the crop [0.
4] with a general purpose insecticide [1.2] okay now the-, wasps are good 
examples of animals which are [0.7] most of us would consider to be pests but 
[0.3] but in fact are on balance very very beneficial because they themselves 
will eat lots of pests [1.0] this wasp here is in a place where [0.2] i don't 
want it to be because it's it's er [0.7] rasping its way through our garden 
bench [1.2] and er when you're sitting out there in the summer reading a book 
or something you can hear this sort of scraping noise what the hell's that you 
look around and there's a wasp [0.7] scraping away at the bench and er [0.6] 
this is made of teak [0.4] i should have [0.3] environmentally friendly teak i 
should point out [0.7] approved by Friends of the Earth [0.6] so this must have 
about the hardest wasps' nest in namex 'cause it's [0.9] scraping away the wood 
to take away to make its er make its nest [0.9] but that's clearly in that 
situation the wasp is a pest [0.9] er also [0.4] if you get wasps on er [0.3] 
apples they're a pest [0.8] 'cause you might end up with [0.6] er with one in 
your mouth [0.4] but on balance wasps are very useful animals because they eat 
very large numbers [0.4] of pests themselves [2.1] okay this is a [0.6] a head 
louse [1.1] er which isn't from my hair i should point out it's from somebody 
who c-, [0.5] who sent it to me [0.5] and er if you remember these these [0.3] 
er head lice have become very [0.6] resistant in recent years to er to 
pesticides [0.6] and er one of the problems is that they will lay their that [0.
2] you can rid of the [0.2] the adults themselves [0.3] but they lay eggs on 
the hair shafts [0.8] and these eggs are very very resistant to the pesticides 
so you have to have two applications of the pesticide to kill off the [0.5] the 
er the [0.2] the baby head lice which hatch out of the [0.2] out of out of the 
eggs [3.4] okay 
flies [0.4] most people would sco-, would consider flies to be pests [0.5] but 
of course flies are er [0.5] very important in decomposition [2.1] and as [0.2] 
maggot larvae [0.8] er if we didn't have flies around [0.4] then er [0.2] we'd 
have dead bodies lying all over the place dead animals [0.4] because flies are 
extremely important in breakdown of materials so [0.4] it's another example of 
an animal which is a pest [0.6] from one point of view in that you don't like 
them buzzing around anno-, [0.4] getting on your food [0.6] but if they were 
absent then there would be er real problems in terms of [0.2] a slowdown in 
decomposition of dead animals [2.2] it's just a load more there [0.6] the pupae 
down here [3.7] right finally this is today's joke [0.8] anybody guess what 
that is [1.5] fly in the ointment [0.2] yeah er [0.4] [laughter] [0.7] right 
okay i think we'll stop there and if we restart at er [0.8] do you want a long 
coffee break today [0.9] 
sm0227: yeah [0.4] 
nm0217: shall we restart at eleven [0.6] 
ss: [0.3] 
nm0217: okay