Pesticide Chemistry: Human Welfare and Environment. Synthesis and Structure-Activity Relationships

376 Pages·1983·17.796 MB·English

by  P. Doyle and T. Fujita (Eds.)

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INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY
(Applied Chemistry Division)
PESTICIDE CHEMISTRY:
HUMAN WELFARE
AND THE ENVIRONMENT
Proceedings of the 5th International Congress of Pesticide Chemistry,
Kyoto, Japan, 29 August - 4 September 1982
Editors-in-Chief
J. MIYAMOTO
Pesticides Division, Sumitomo Chemical Co., Ltd.
Takarazuka, Hyogo, Japan
and
P. C. KEARNEY
Agricultura] Environmental Quality institute, US Department of Agriculture,
Beltsville, Maryland, USA
Volume 1
SYNTHESIS AND STRUCTURE-ACTIVITY RELATIONSHIPS
Volume Editors
P. DOYLE
ICI Plant Protection Division, Bracknell, Berkshire, UK
and
T. FUJITA
Department of Agricultural Chemistry, Kyoto University, Japan
PERGAMON PRESS
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First edition 1983
Library of Congress Cataloging in Publication Data
International IUPAC Congress of Pesticide Chemistry
(5th: 1982: Kyoto, Japan)
Pesticide chemistry, human welfare and the environ
ment.
(IUPAC symposium series)
At head of title: International Union of Pure and
Applied Chemistry. Applied Chemistry Division.
Congress organized by The Science Council of Japan,
Pesticide Science Society of Japan, and the Japan
Plant Protection Association.
Includes bibliographical references.
1. Pesticides—Congresses. I. Miyamoto, J.
(Junshi) E. Kearney, P. C. (Philip C), 1932-
III. International Union of Pure and Applied Chemistry.
Applied Chemistry Division. IV. Nihon Gakujutsu
Kaigi. V. Nihon Nóyaku Gakkai. VI. Nihon Shokubutsu
Bóeki Kyókai. VII. Title. VIII. Series. [DNLM:
1. Pesticides—Congresses. 2. Pesticide—Residues—
Congresses. 3. Toxicology—Congresses. 4. Pest
control—Congresses. WA 240 P4738]
SB950.93.I57 1982 632'.95 82-24602
British Library Cataloguing in Publication Data
International Congress of Pesticide Chemistry: (5th:
1982: Kyoto) Pesticide chemistry.
1. Pesticides. Environmental aspects—Congresses
I. Title II. Miyamoto, J. III. Keaney, P. C.
IV. International Union of Pure and Applied Chemistry.
Applied Chemistry Division
632'.95042 QH545.P4
ISBN 0 08 029219 4 (4 vol set)
ISBN 0 08 029222 4 (volume 1)
In order to make this volume available as economically
and as rapidly as possible the authors' typescripts have
been reproduced in their original forms. This method
unfortunately has its typographical limitations but it is
hoped that they in no way distract the reader.
Printed in Great Britain by A. Wheaton & Co. Ltd., Exeter
Organizing Committee
Chairman: M. Nakajima
Vice Chairman: H. Fukami
Secretary Generai: T. Misato
Members: T. Endo, M. Eto, T. Fujita, S. Goto, T. Hosotsuji, W. Iida, T. Iwata,
A. Kawana, K. Koshimizu, N. Kurihara, S. Kuwatsuka, S. Matsunaka, T. Mitsui,
J. Miyamoto, J. Mizutani, K. Munakata, M. Saito, T. Saito, N. Takahashi,
S. Takahashi, T. Tanaka, M. Uchiyama, K. Ueki, T. Ueno, I. Yamamoto,
K. Yamashita, K. Yasutomi
Scientific Programme Committee
Chairman: J. Miyamoto
Vice Chairman: P. C. Kearney
Members: P. Doyle, N. Drescher, T. Fujita, S. Goto, R. Greenhalgh, D. H. Hutson,
S. Kuwatsuka, S. Matsunaka, S. D. Murphy, N. Takahashi
Congress Organizers
The Science Council of Japan
Pesticide Science Society of Japan
Japan Plant Protection Association
INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY
IUPAC Secretariat: Bank Court Chambers, 2-3 Pound Way,
Cowley Centre, Oxford 0X4 3YF, UK
PREFACE
The Fifth International Congress of Pesticide Chemistry, sponsored by the International
Union of Pure and Applied Chemistry, and organized jointly by the National Science Council
of Japan, Pesticide Science Society of Japan and Japan Plant Protection Association, was
held at Kyoto International Conference Hall in Kyoto, Japan, 29 August - 4 September
1982. The opening of the Congress culminated four years of intensive planning by the
Scientific Programme Committee, the Organizing Committee, and a host of internationally
recognized scientists dedicated to pesticide chemistry. The main theme of the Congress,
Human Welfare — Environment — Pesticides, was intended to encompass current research
topics in pesticide chemistry, not only for increased agricultural production, but also
for public health purposes. Xenobiotics other than pesticides were also included. One
thousand, six hundred scientists from 55 countries attended the Congress.
Two distinguished scientists, Professor Dr. K. H. BCichel, Bayer AG, Leverkusen, FRG, and
Dr. I. J. Graham-Bryce, East Mailing Research Station, UK, presented plenary lectures
dealing with political, economic and philosophical aspects of pesticide use, as well as
future pesticide research for improving human welfare. A number of distinguished invitees
also addressed the Congress participants, including the President of IUPAC, Professor
S. Nagakura.
Eight main topics were selected as the subjects of the Congress, either because of their
timely nature or because the area needs critical review. They included: Synthesis of
Pesticides and Growth Regulators; Chemical Structure and Biological Activity; Bioactive
Natural Products: Chemistry, Biochemistry and Physiology; Biochemistry of Pests and Mode
of Action of Pesticides (including Mechanism of Resistance and Phytotoxicity); Metabolism
and Degradation of Pesticides and Xenobiotics; Toxicology of Pesticides and Xenobiotics;
Pesticide Residues and Methodology; and Formulation Chemistry. Each main topic included
one symposium and several poster-discussion sessions.
Each symposium consisted of several invited presentations, providing the participants with
current and provocative overviews on important aspects of the respective topics.
Poster-discussion sessions constituted the main body of presentations to the Congress and
were intended to cover a wide variety of areas. Each included a few invited papers in
addition to the contributed papers. Invited scientists served as leaders during the
follow-up discussion after the poster presentations. Overall the Congress was organized
into 49 sessions under the eight main topics with 694 submitted papers, including 236
invited papers.
In addition to the eight main topics encompassed by the Congress, three complementary
symposia dealing with related subjects were held simultaneously, with 31 invited
presentations: Pyrethroid Insecticides — Biological Activity, Mode of Action, Metabolism
and Toxicology; Antibiotics for Agricultural Use; and Herbicides and Plant Growth
Regulators for Rice Culture.
The proceedings of the Congress, entitled Pesticide Chemistry: Human Welfare and the
Environment, comprise four volumes containing over 250 invited papers presented at the
symposia, complementary symposia, and poster-discussion sessions. Specifically, the
contents are: Volume 1: plenary lectures, synthesis, structure-activity; Volume 2: natural
products, complementary symposia; Volume 3: mode of action, metabolism and degradation,
toxicology; and Volume 4: residue analysis, formulation chemistry. It is sincerely hoped,
by this overview of the present status of chemical and biochemical pest control, that
readers gain an appreciation of how pesticide science continues to contribute to human
welfare.
Junshi Miyamoto
Philip C. Kearney
PC 1 - A*
IX
POLITICAL, ECONOMIC AND PHILOSOPHICAL
ASPECTS OF PESTICIDE USE FOR HUMAN
WELFARE
K. H. Biichel
Bayer AG, 5090 Leverkusen, Federai Republic of Germany
INTRODUCTION:
I. PESTICIDES IN AGRICULTURE
1. At the farm level
a) Loss prevention
b) Farm economics as safeguarded by the use of
insecticides, fungicides, herbicides, growth
regulators and others
2. Agriculture and food policies
a) Food supply
b) Nonedible crops
c) Aspects in regard of developing countries
II. PUBLIC HEALTH SECTOR
1. Nutrition as a basis for human welfare
2 . Control of vector-borne diseases
3 . Clean food: Mycotoxins and other naturally occur
ring food contaminants
III. SAFETY ASPECTS
1. Safety in the manufacture and application of pesti
cides
2. Safety of the food consumer
3. Environmental aspects
a) Behaviour of pesticides in soil, including lea
ching, microorganisms and soil invertebrates
b) Effect of pesticides on plants and wildlife
c) The ecosystem and the balance of nature
IV, LEGAL ASPECTS
1. Pesticides regulation secured by existing legisla
tion
2. The need for harmonization
3. Consequences of overregulation
V. FORWARD EDGES IN CROP PROTECTION
1. Genetic engineering for better crops
a) Plant resistance against pests, diseases and agroche-
micals
b) Improvement of plant productivity
c) Influencing of wanted or unwanted plant ingre
dients
d) Influencing of plant growth properties
2. Renewable resources (biomass)
a) Biomass for energy
b) Raw materials from biomass
3. Conclusions: Agrochemicals in future crop protec
tion
3
4 K. H. Büchel
INTRODUCTION
The problem of our days is not so much the oil crisis, the econo
mic recession, the discussion on nuclear power, the conflict
between different social systems or the armament race, but the
real problem is to guarantee the nutrition of mankind.
400 to 500 millions of people in our world still suffer from
hunger, and every year the world's population increases by about
80 million people. The task of our days is to improve the state
of world nutrition (Ref. la).
This can be achieved by a bundle of measures. One important tool
are the agrochemicals and pesticides.
The potential and actual influence of these substances, not only
on agriculture but also on the socioeconomic conditions in both,
the developed and the developing countries, is far-reaching.
PESTICIDES IN AGRICULTURE
At the farm level
The original and main use of pesticides is the prevention of crop
losses at the farm level. As a consequence of the spectacular
successes achieved in this field, the importance of agrochemicals
to farm economics in general became evident. By permitting the
use of improved machinery, and less soil cultivation, the use of
pesticides has enabled the net return on farm investment to be
improved and stabilized. Today, therefore, crop protection is an
integral part of modern farming.
There are two aspects of special importance at the farm level
a) The yield loss has to be kept below the so-called economic
threshold. Since the investment per unit area is more or less
a fixed sum, yield losses will, expressed otherwise, directly
reduce the net income. If for example the profit in absence
of any loss is 20 %, a 10 % loss would reduce the earnings by
50 %. A loss of more than 20 % would already be intolerable.
(Ref. lb; Fig. 1).
Fig. 1.
b) Especially in the developed countries, manpower must be re
placed by mechanization and the use of agrochemicals. This is
demonstrated by the development of wages for agricultural
workers, on the one hand, and prices for tractors and pesti
cides, on the other hand, during the period 1970/71 to
1978/79, in the Federal Republic of Germany (Ref. 2). Figure
2 clearly shows the real background of the still increasing
importance of herbicides in farm economics. The farmer has no
other choice than to make use of easy to handle, relatively
cheap, safe and effective chemicals instead of highly paid
workers .
Political, Economic and Philosophical Aspects of Pesticide Use 5
Fig. 2
However, not only this monetary consideration has contributed
to the world-wide acceptance of herbicides in modern farming;
many others have played a part. One of them is the non or
minimum tillage farming method, which - in dry regions - con
tributes to the conservation of the moisture in the soil,
saves energy and reduces soil erosion. (Ref. 3).
Mechanical harvesting of many crops, esspecially of cereals
with combines, is possible only if the crops are essentially
free of weeds. For combine harvesting the moisture content of
the ears must be as low as suitable (Ref. 1). Weeds retain
moisture in the crop.
Herbicides, therefore, are sometimes essential to the fully
efficient utilization of expensive machinery.
If the crop has not to overcome any weed competition for wa
ter, and mineral fertilizers, it can make nearly full use of
its own genetic capacity. But still other problems can occur.
One is that the crop is allowed to grow so dense that the
microclimatic conditions, may favour the development of cer
tain parasitic fungi, such as mildew and rust. Another side
effect is that the weight of the ears in relation to the
stalks may become so heavy that it causes lodging of the crop
with all it's undesirable results. Finally, the well fed
cereal crop may be attacked by sucking insects like aphids
(Ref. 4). These examples show to what degree modern research
permanently has to solve new problems. Figure 3 shows not only
the huge differences in the yield per hectare of one of the
world's most important crops, wheat, but also the magnitude
of the world's food reserves if modern agriculture is applied
(Ref. 5).
Fig. 3 Fig. 4
6 K. H. Büchel
Cereal diseases can now be effectively controlled by safe,
economical, and ecologically favourable fungicides. The prob
lem of lodging could be solved by growth regulators which im
prove the stability of the stalk, and thus permitting better
use of fertilizers. The control of aphids is no problem. So
yield levels which would have appeared unbelievable only a
few decades ago are possible. In addition, Fig. 4 shows, to
what extent stabilization of yields, and therefore their cal-
culability have become possible.
Agriculture and food policies
If a crop loss for the single farmer threatens his economic exi
stence, crop losses on a world basis threaten the very existence,
or survival, of millions of people.
Figure 5 shows one of the most alarming developments that have
occured since the beginning of the energy crisis. For several
years the world production of cereals has been unable to keep up
with consumption (Ref. 6); as a result, carry-over stocks are
dwindling year by year. According to official statements of the
USDA, the grain stocks of the world have dropped in 1981/82 to
their lowest level since the Second World War. We have to realize
that during the last five years the world's total output of
cereals has exceeded consumption only by an amount sufficient for
slightly more than four days. During the last two years, indeed
there has been a deficit to about 70 million tonnes. The stocks
are running down.
Fig. 5 Fig. 6
In face of this situation it seems almost unbelievable that more
than an estimated third of the world's total potential harvest is
still being lost to insects, plant diseases and weed competition.
Figure 6 shows some calculations of the FAO, as published until
1978, for five of the world's most important crops (Ref. 7).
The total loss in rice growing is equivalent to the total rice
production of Asia, excluding Japan and Thailand, in 1980. In
wheat growing the loss is equivalent to the total production of
Asia and Australia. Most of these losses could be prevented by
application of the present-day know-how and the available pesti
cides (Ref. 8). I would like to draw your attention to a resolu
tion, passed at a meeting of several UN organizations and the
World Bank in late 1981 (Ref. 9), which stated the following: "If
Political, Economic and Philosophical Aspects of Pesticide Use 7
it were possible to reduce the crop losses by only 15 %, this
would result in an additional production of 100 million metric
tonnes of cereals. This would be equivalent to the food supply of
nearly the same number of people." Expressed in cereal prices the
equivalent is about 16 billion $, which is exactly the amount of
money spent annually by the industrialized nations on aid to
developing countries.
These considerations are not, of course, restricted to edible
crops. Many other agriculturally grown raw materials, such as
natural fibres (e.g. cotton, hemp, sisal) and natural rubber,
constitute the backbone of the national economies of the pro
ducing countries and represent a high export value. Cotton,
today, without chemical protection, would be an article of exclu
sive luxury. The extent to which the cotton harvest is safe
guarded by crop protection measures is demonstrated by Fig. 7.
This shows how improved control methods in a Central American
Country changed the situation of the whole cotton industry within
only a few years, giving the crop a key position in the national
economy (Ref. 10, 11). Since 1962 there were no major changes ir
the cotton growing area of the country.
Fig. 7
This leads directly to the question of the impact which pestici
des have or could have on the economies of the countries of the
Third World. We have to take into account that there are really
two different problems. The first is the problem of producing
sufficient food for increasing populations; the second is the
need to make agricultural production an efficient part of the
general economy of these countries. In terms of the direct food
supply one has to make a distinction between so-called
subsistance crops, the staple food crops, and the cash crops.
In my view, there is no doubt about the key function of subsist
ance crops - be they cassava (manioc) in some countries or
several cultivars of millet in others or the wide range of local
crops in several parts of the southern hemisphere. These plants
are grown under conditions which keep them far below their
genetic potential. To improve the food supply under the local
conditions of different countries by optimizing the yield and
nutritional value of these crops is undoubtedly one of the most
urgent tasks for plant breeders and agricultural experts. Crop
protection products will be needed to assist them. As regards
staple foods like cereals or potatoes, rationalization in the
developed countries has already reached levels that hardly can
be achieved by the developing countries. It must be realized,
that for the next few decades it will be possible to produce
staple food crops more cheaply in the developed countries. There
is no doubt that herbicides have contributed considerably to this
situation and will continue to do so.