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IPM OF RED PALM WEEVIL
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level, for a long time (El-Sebaey, 2004a). In this respect, this author carried out
an experiment using chemical insecticides to kill all developmental stages of
RPW surviving in such trunk bases. Big holes were made in the bases, using a
sharp axe, to facilitate penetration of insecticides downward through the base
tissues. Six chemical insecticides, dissolved either in water or kerosene, were
poured at rates ranging from 5 to 10 l/base. Two weeks later, the treated bases
were picked up using a loader machine and cut into parts to allow inspection of
alive and/or dead RPW stages, inside the base and root system. The experiment
showed that the insecticides Cidial (phenthoate), Basudin (diazinone) and
Dursban (chlorpyrifos-ethyl), dissolved in kerosene, caused 100% mortality in
larvae and pupae. As for adult weevils they caused 95.6, 95.2 and 97.6%
mortalities, respectively. However, the same insecticides, dissolved in water,
caused 57, 53 and 49% mortalities in larvae, 37, 55 and 48% mortalities in
pupae, and 25, 25 and 26% mortalities in adults. The author related the
synergistic action of kerosene to three factors: (i) its function as a good carrier
for the chemicals throughout the wood fibers deeply inside the infested roots,
(ii) its physical action on the wood as a dehydrated substance which caused
wood dryness faster than insect survive, and (iii) its effect on dehydration and
toxic action on the insects' cuticle.
5.1.2. Injection
Injection of insecticides into the trunk of the coconut palm was first reported by
Rao, Subramaniam, and Abraham (1973), who demonstrated that the direct
injection of 0.2% fenthion gave effective control of larvae in the tree.
Muthuraman (1984) reported that 10 ml of monocrotophos or dichlorovos
injected into a pre–drilled 10 cm deep hole above the infestation site gave 100%
recovery of the treated infested trees. In Egypt, El-Sebaey (2004b) tested 15
chemical insecticides against RPW infestation by injecting them at different
concentrations in 4–10 holes (10 cm deep), drilled around the infestation site.
This author found that all tested chemicals showed 100% recovery of infestation
at a concentration of 10,000 ppm, while at 100 ppm dursban, curacron and cidial
gave 80% recovery.
An alternative to injecting insecticides into the tree is sealing, inside the tree,
a tablet form of a slow release fumigant. Phostoxin tablets (aluminum
phosphide) applied at a rate of 0.5–1 tablet per tree was effective in killing
larvae, pupae and adults of RPW on coconut (Rao et al., 1973).
Muthuraman (1984) used two 3 g celphos (aluminum phosphide) tablets
crushed, placed in holes in date palms and sealed with a paste of cement and
copper oxychloride.
Abd-Allah and Al-Khatri (2000a) compared the effectiveness of injecting
chemical insecticides and using fumigation tablets (aluminum phosphide)
against RPW infestation. In this experiment, three holes (30 cm deep and 1.9 cm
wide) were drilled into the tree: one at the point of infestation (where the brown
bad smell sap was oozing), the second 20 cm above and the third 20 cm below
the first hole. Into each hole 50 ml of the insecticide formothion 33% was
poured using a plastic tube (45 cm long and 1.3 cm diameter). The holes were