and Integrated Pest Management - part - usaid

IIST M,',ANAGEMpI'r ON COCO,', INMALAYSIA
not entire fields, are treated, thus avoiding indiscriminate app'ication of
pesticides.
A feature of mirid chemical control in Malaysia that is original to the
country is !be emphasis on early warning of outbreaks through census systems.
Wiils (1984) and Wood (1984) describe the success of two stuch systems in
providing ecologically sound control at economic cost.
The present great aependency on chemicals to control lielopellisin Malaysia
reflects the general inability and lack of effective natural control agents to
suppress the populations to below economic levels. The only predator that
shows prospective use as a biocontrol agent is the cocoa black an', Dolichoderus
thmracicus (Azhar 1986) and work is being carried out to elucidate ways of
effectively using the organism for such a purpose.
No effective cultural control method, whether by shade manipulation or the
use of resistant planting materials has been developed (Azhar 1986).
CONTROL OF BORERS
Stem and Trunk Borers
Although a complex of such borers that telong to !he genus Zeuzera are
known to attack a varic;v of trees in Southeast Asia (Barlow 1982), Z. coffeae
and Z. roricyaneaar. the most commonly encountered in cocoa of Malaysia.
The insects are almost alwa,.ys present in established cocoa plantings. They are
often underrated, however, due to the insects' relatively undra-'aic mode of
infestation.
Zeuzera are damaging during the larval stages of its lifecycle, description of
which is as in Conway (1971). If left untreated, the borers can easily reach
epidemic proportions, recent experience showing the insect reaching levels of up
to 6,500 larvae per ha of cocoa, causing severe de.sication of foliage through
hollowing out of branches and loss of crop through damage of trunks. Trees are
also known to die, and survivors cften rendered unproductive.
The key to avoidance of the foregoing damage is early det(.ction and
sustained control of manifestations so that borer levels are rendered
inconsequential. If early detection is achieve,,, a combination of cult,';al and
insectic.de trc.a'ment is effective, the fornier being pruning of light branches with
borers, inspecting branches to kill any larvae present. Parasitized larvae (e.g., by
the Ichneumonid Spinariasp.) are, however, undisiurbed and left in the field for
parasitoids to emerge. Chemical treatment, basically on trunks and infested
h.anches that are too thick to be pruned, entail the pumping of a dieldrin or
ekilorpyrifos solution into bores.
With emphasis on early detection, census is once again instrumental for
success. Scoiing of borer activity in conjunction with earlier mentioned
lielopeltis census rounds l, ve been experienced to provide the required
sensitivity.
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