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Ecological effects of two new insecticides (fwd)
Sender: ag-impact@freedom.mtn.org
From: Steffen Johnsen <stefulla@post8.tele.dk>
To: Multiple recipients of list <ag-impact@freedom.mtn.org>
Ecological effects of two new insecticides - Fipronil and
Lambda-cyhalothrin -
in rice paddies.
Fipronil and lambda-cyhalothrin are both intensively marketed in Asia
for use i rice, and their producers (Rhone-Poulenc and Zeneca
respectively) claim the products to be compatible with IPM practices.
A development project sponsored by the Danish Government, in Vietnam,
undertook field studies to investigate these claims.
The major findings were:
1) Natural pest control was far superior to the use of any of these
chemicals, provided the fields had not previously been damaged by
pesticide use.
2) Both chemicals had negative impact on this natural control and
indications were seen that lambda-cyhalotrhin may induce severe pest
problems.
3) Fipronil has some disturbing effects on several groups of aquatic
organisms, mainly crustaceans. This calls for extreme caution when it
is used in paddies. because the floodwateroften is more or less
continuous with water used in shrimp farming.
4) In the marketing of lambda-cyhalothrin the company quotes a study
performed at PhilRice which documents only transitory and small negative
effects on natural enemies of pests. This study could replicate these
findings only in a field which was already severely damaged by frequent
insecticide applications. In undisturbed fields lambda-cyhalothrin had
very severe negative impact on all groups of natural enemies.
5) In the marketing of fipronil it is stressed that it often improves
yield in paddy rice. This study made the same observation and went on to
compare effects of fipronil (in a granular formulation, 'Regent 0.3G')
with that of a foliar fertilizer, containing micronutrients, in a well
fertilized and a poorly fertilized farmers field. In the former neither
Regent nor the foliar fertlizer had any effects on yield, while in the
latter both increased yield by about 15%. Chemical analysis of the
Regent formulation seem to confirm that it does contain microutrients.
The project is now completed. Full reports and further information may
be obtained from the advisor who headed it. He may be contacted at:
stefulla@post8.tele.dk