Ecoscript 51

Gerrits & Van Latum. Plant-Derived Pesticides in Developing Countries.

The use of plants with toxic or repellant action against pests
is a common crop protection practice in traditional agricultu-
ral systems in developing countries. If these plants are loc-
ally abundant and the pesticides easily extractable,the plant-
derived pesticides can be supportive to maintain a "low-input"
agricultural system and improve local food-selfsufficiency. If
plant-derived pesticides can be produced and obtained easily
at low costs from local plants both subsistence farming and
cash crop farming may benefit from it. Development strategies
for the rural poor usually emphasize small-scale agricultural
development that allow low-income farmers to produce subsis-
tence and cash crops with minimal dependance on external
inputs (Glaeser, 1983; Latum, 1986; Werf, 1983; ILEIA, 1987).

Plants containing biotoxins can be more interesting than syn-
thetic chemical pesticides due to its inherent combination of
chemical substances. It is harder for insects to develop res-
istance to combinations of plant-derived chemicals, than to
single compounds. Some natural biotoxins, when they have been
tested carefully, may prove to be of great promise for being
used as natural pesticides, for example neem. This enables de-
veloping countries to produce a substance for use even in the
developed countries.

However, plant-derived pesticides should not be uncritically
idealized. They are natural toxins that need to be scrutinized
carefully. Serious harm may result equally much from overexpo-
sure to some of such substances as to certain synthetic chem-
icals. Numerous are the biotoxins and other natural materials
that can cause acute or chronic poisoning, sometimes in remar-
kably small quantities (IRPTC, 1983).

This study provides an overview of the most important litera-
ture with regard to plant-derived pesticides in developing
countries and aims at:
* raising international awareness for:
- the potentials of plant-derived pesticides;
- the need to install a database to stimulate and promote
further research;
- the importance to save the genetic diversity of plants,
particularly in the tropics, where many plants with pesti-
cidal properties happen to be found;
* indicating criteria under which safer use of plant-derived
pesticides can be reached inter nationally. Pesticides deri-
ved from the neem tree are taken as an example.
* highlighting problems in the registration process in Europe
and North America of plant- derived pesticides originating
from developing countries. The Netherlands are taken as an
example, being the country with the most stringent pesticide

This study should also stimulate further research. Neem is
taken as an example to illustrate the connection between
research, production of the pesticide and its application.

The study surveys the most important literature and principal
handbooks on plant-derived pesticides. Based on this informat-
ion criteria for the safer use of plant-derived pesticides are
developed to give guidance to the use of such pesticides in
developing countries.


Introduction 7
.. Aim of the study 7
.. International awareness 7
.. The need for closer study 8
.. The social viewpoint 8
.. Future research 9

Acknowledgements 10

Neem: A Promising Plant-Derived Pesticide? 11
.. Criteria for plant-derived pesticides 11
.. Neem extracts: the "premium" plant-derived pesticide 12
.. Research needs 13
.. Overview of current research on neem 14
.. Conclusion 14

Legislation Policies Pertinent To plant-Derived Pesticides 15
.. US-legislation on plant-derived pesticides (EPA, 1982) 15
.. "Minor use of pesticides" 15
.. Biorational pesticides 15
.. Biorationals and data requirements 16
.. Implications for developing countries 16
.. European Community legislation on plant-derived
pesticides 16
.. United Kingdom, The Netherlands and Federal Republic of
Germany 17
.. Implications for developing countries 18

Case studies:Rotenone, Quassia, Ryania, Pyrethrum and Endod 19
.. Rotenone (Derris elliptica Benth.) 19
.. Quassia (Quassia amara Simaroubaceae, Ailanthus) 20
.. Ryania (Ryania spp., Flacourtaceae) 21
.. Pyrethrum (Chrysanthenum cinerariifolium) 22
.. Endod (Phytolacca dodecandra) 22
.. Pesticide legislation in the Netherlands with regard
to plant-derived pesticides 23
.. The actual registration problems with rotenone and
ryania 24
.. Description of tests needed for registration of rotenone 25
.. Implications for developing countries 26

Conclusions and Recommendations 28
.. Conclusions 28
.. Recommendations 28

Literature 30

Appendix A: Literature review on plant-derived pesticides 36
.. Evaluation of literature 36
.. Libraries consulted 37
.. Overview of selected literature 38

Appendix B: Data about plant-derived pesticides 44
.. Mode of action of neem products 44
.. Preparation of neem products 44
.. Pests affected by neem products 45
.. Effects of neem products on non-pests 45
.. Some disadvantages and advantages of neem 46
.. Potential of neem 46
.. Remaining uses of the neem tree 47
.. International projects and research on neem 47
.. The three international neem confences 48
.. Legislation and patents 49
.. The industry 50
.. Other pesticidal plants besides the neem tree 50
.. Future co-operations and finances 51

Appendix C: Pesticide legislation USA, West-Germany, United
Kingdom and The Netherlands 52
.. History of USA-pesticide legislation 52
.. Biorational pesticides 52
.. Biorationals and data requirements 53
.. The tier I test for biorationals 53
.. United Kingdom, The Netherlands and West-Germany 54

Appendix D: Addresses 56