and Integrated Pest Management - part - usaid

)M A(:I'IV'IIB.S INC(X:()N1S 183
conditions of breeding material as a result of regular rainfall and high relative
humidity. Fungus preparations proved to remain infective to larvae for at !east
24 months.
COVER CROPS Young coconut palms, replanted in areas where logs and
stumps of former coconut cultivations cannot be removed, can be protected by
planting leguminous cover crops such as Puerariaspp., Centrosoma spp., and
Calopogonium spp. These legumes provide a dense vegetative barrier which
protects young palms from attack by beetles and greatly reduces oviposition in
rotting logs and stumps.
SURVEYS Regular rapid damage surveys are practical tools for assessing
recent beetle attacks on palms (Peterson 1977). The incidence of virus infection
in adult beetle populations should be determined semiannually.
Recent Findings
Under the GTZ project and a preceding SPC/FAO/UNDP project, the
Western Samoan coconut palm area of about 59,000 hectares (Ward et al. 1980)
has been under constant supervision since 1964. Results show the high
incidence of virus infections persisting in the beetle populations of Western
Samoa. At the same time damage remained at low levels.
The Philippine Example
In the Philippines, we find a different situation regarding the rhinoceros
beetle. The beetle is considered the most important insect of the coconut palm
(Anon. 1978). In particular, a countrywide rehabilitation program to substitute
the overaged plantations with new hybrid varieties is severely endangered. This
is underlined by the figures in 1 Tr , e The figures in Table
1. 1 also clearly
indicate the importance of proper sanitation measures.
The Baculovirus of Oryctes is autochthonous within the Philippines
rhinoceros beetle population. From preliminary studies by V. Fandialan (pers.
communication 1979), it appears that its incidence in adults is rather low (7­
12%) in the province of Quezon (Huger 1979). Apparently, virus transmission
within beetle populations is impaired by special population dynamics resulting
from dry conditions in this area during several months of the year.
Table I. Difference in rhinoceros beetle incidences between various ecosystems.
1st Year 2nd Year 3rd Year
Replanted old palm areas 15.3% 32.7% 22.9%
Partly replanted and
partly newly planted areas
Newly planed areas
2.4%
2.2%
7.8%
7.8%
14.4%
8.9%