and Integrated Pest Management - part - usaid

36 PES'I1CIDE MANAGIEMENT AND P2M INSOUTIIEAS' ASIA
relation to the life cycle of the pest, e.g. young larval stage of leaf eating
caterpillars (see Figure 2).
Cultural Measures
Sometimes a simple cultural measure can reduce pest risk, e.g. the palm
rhinoccros beetle is restricted both from its breeding sites and from attacking
palns oy dense vegetation. Young replantings tend to be vulnerable because the
beetle breeds in the tissues of the previous stand. By felling the stems of old
palms and establishing and encouraging ground vegetation, attack generally
remains below economically serious levels. The effect of harvesting frequency
and technique on the incidence of cocoa pod borer was mentioned above.
Bagging of individual fruit ispracticed against fruit flies (Vijaysegaran 1983) and
isoften useful for CPB (Wardojo and Moersamdono 1984).
Resistance
Plant resistance is less often considered against insects than diseases. Rapid
selection in perennial crops isdifficult because of their long generation time and
large size. However, many are planted as clones, and more (in particular oil
palms and cocoa) are moving towards this. Thus the possibilities of finding
resistant types and multiplying them with sufficient speed will increase. There
are few comniercial scale examples at present, but thickness of the sclerotic layer
in the pod husk is being considered as part of the approach to CPB control (Day
1985).
Biological Control By Natural Enemies
INCREASING ENVIRONMENTAL SUITABILITY Syed and Shah (1977)
suggest that blanket removal of weeds, by destroying the food sources of adult
parasites, was a factor that precipitated caterpillar outbreaks in oil palns in
Sabah. Generally, plantations allow some weeds to remain. An ant
Dolichoderus bituberculatuscan exclude Itelopeltis spp. key pests on cocoa (Isa
1985, Khoo & Muliineed 1986). Measures to ensure the establishment and
prominence of this species would constitute a good IPM approach. Numerous
other examlples exist.
MASS REARING AND INUNDATION 'This method is more often used in
seasonal situations, where a pest increases at a favorable time and the natural
enemies do not build up fast enough to prevent economic damage. Inundation
with laboratory reared enemies at this period gets over the period of imbalance.
It is less widely used in tropical perennial crops due to the need for constant
releases, but interesting results have been obtained with egg parasites against
lepidopterous borers in sugarcane (Lira 1972) and against CPB in cocoa (Lim et
al. 1982).
IMPORTATION The establishment of exotic natural enemies has been rather
neglected in perennial crops in Southeast Asia in general, but there are a few