and Integrated Pest Management - part - usaid

4 PEI-:S'ICIDE MANAGIMEIl.NI AND IPM INSOUTHFEAST ASIA
(Castaneda & Maramba 1984, Reissig et al. 1982). Two examples illustrate the
effect of pesticides on non-target species and as a cause of secondary pest
outbreaks: the first was the destruction of inland and coastal fish populations in
East Java following aerial application of endosulfan on rice fields in 1968, and
the second was the outbreak of rice gall midges in West Java subsequent to the
aerial spraying of phosphanidon to control rice stemborers in 1969 (Oka 1983a,
b). Pesticide residues in foodstuffs, particularly in vegetables, are also of much
concern. Although farmers are commonly told that the last pesticidal spray on
vegetables should be carried out at least two weeks before harvest, they
nevertheless keep spraying. This is partly due to the changing aititudes of
consumers, who prefer unblemished vegetables. Cases have also been reported
of DDT contamination of export commodities like tea and tobacco.
Adulteration of pesticides, cross-labelling, rebottling, and repackaging,
frequently occur. In view of the projected demands for pesticides in Southeast
Asia in the near future, the problems of toxicity, pest resistance, resurgence, and
other unwanted side effects certainly will become more serious. Therefore,
proper pesticide management throughout the region is a must, and existing
management practices should be improved. Good pesticide management will
strengthen the implementation of IPM programs in Southeast Asia.
TIlE CONCEPT OF PESTICIDE MANAGEIENT
Selectivity
To increase the "harmony" of integrating pesticides with non-chemical
control tactics, the pesticide to be used should be selective, i.e., it should only
destroy pests with little or no side effects on non-target animals or plants.
However, such ideal conventional pesticides with intrinsic selectivity qre rare
(Way 1977). Moreover, intrinsic selec;tiy,'i;.,, if piubuiit, is limited to only a
group of non-target species. For example, penmethrin and fenthion are selective
in favoring mammals (Norway rats), but not very selective in favoring fish
(trout) (Reissig et al. 1982). Consideration of pesticide selectivity in favoring
fish is very important in rice-fish cultures. Of special relevance is selectivity of
pesticides to favor natural enemies of pests and beneficial insects. In rice pest
control, pyridafenthion and tetrachlorvinphos are highly selective, favoring the
wolf spider Lycosa pseudoanlnulata, but toxic against its prey, the green
leafhopper. Lindane and fenthion, on tie other hand, selectively favor the pest.
Malathion, diazinon, and carbaryl have selective values of 2.7, 1.5 and 2.3
respectively, and may be less toxic to Lycosa than to the pests (Shepard &
Brown 1984). Insectistatic chemicals (molting inhibitor) like buprofezin have
been reported to be highly effective against BPH and to be safe for its natural
enemies (Sogawa, pers. comm.).