and Integrated Pest Management - part - usaid

PESTICIDE RESISTANCE PROBLEMS IN MALAYSIA
K. 1-. Tan
School of Biological Sciences
Univcrsiti Sains Malaysia
Minden, 11800 Penang, Malaysia
Pesticide resistance was recorded as long ago as 1911 when extensive
fumigation of citrus trees had selected a strain of scale insect resistant to
hydrogen cyanide gas (Busvine 1976). The widespread use of pesticides after the
Second World War, and the dependence on them, meant that when pesticide
resistance became prevalent, the phenomenon had a profound effect on pest
control hoth in the agricultural and public health scctors. The growth in
incidence of pesticide resistance since 1947 was acclerated by the introduction of
large-scale usage of new synthetic pesticides. On a worldwide basis, 52
agricultural species ind a similar number of medically important species had
developed resistant strains by 1958. In subsequent years, however, the number
of agricultural pests that developed resistant strains have far exceeded the number
for medical species. It was rcporLcd in 1976 that 225 of the 304 (305 confirmed
and 59 Suspected) arthropod species resistant to pesticide.s were of' agricultural
imporntce (Gcorghioil & Taylor :976). Recently, on re .ird at least 447 species
of insects and mites have developed resistance to insecticides (Georghiou 1986).
Resistance to almost every conceivable type of pesticide has been reported.
I litherto, resistance has bcen reported for such diverse and new pesticides as the
insect chitin inhibitors Dimilin in Musca d mestica L. (Cerf & Georghiou
1974); the insect's own hormone, synthetic juvenile hormone in Tribolium
castaneumHerbst. (Dyte 1972); the microbial insecticide Bacillus thuringiensis
in A. domestica (WHO 1986); the anticoagulant rodenticide warfarin in rat
Ratus norvcgicus 1crL.(Drumnond 1966) and iouse Ms mtusculus L. (Rowe
& Redfern 1965); and the highly toxic herbicide paraquat in Erigeron
philatdelphicusL. (Watanabe et al. 1982).
In Malaysia, various groups and types of pesticides have been used over the
past three decades. It is surprising to note that with the widespread and/or
continuous use of herbicides, and to a lesser extent molluscicides and
ncmaticides, no case of resistance has been reported. Since the general review of
insecticide resistance in agricultural pests in Malaysia in 1979 by Sudderuddin
(1979), a few more cases of resistance have been reported. The aims of this
paper are to discuss a) cases of biochemical mechanisms involved in resistance,
b) possible ways to overcome resistance problems, and c) regiona" as well as
international cooperation, particularly within the Southeast Asian region.