Journal of Oil Palm Research Vol. 28 (3) September 2016, p. 296-307

DIVERSITY AND ACTIVITY OF INSECT NATURAL ENEMIES OF THE BAGWORM (Lepidoptera: Psychidae) WITHIN AN OIL PALM PLANTATION IN PERAK, MALAYSIA

NORMAN KAMARUDIN* and OTHMAN ARSHAD*

DOI: https://doi.org/10.21894/jopr.2016.2803.06
ABSTRACT

Bagworms (Lepidoptera: Psychidae) are one of the important leaf-eating pests of oil palm in Malaysia and Indonesia. Crop losses, due to the extensive defoliation by a serious bagworm attack are inevitable. The establishment and propagation of the bagworm’s parasitoids, depend very much on species of flowering plants as sources of nectar. Cassia cobanensis, was proven suitable due to its attractiveness to most bagworm parasitoids. A study to assess the diversity of bagworm’s natural enemies (hymenopterous parasitoids and reduuvid predatory bugs) on the C. cobanensis plant and within the undergrowth of the oil palm planting block was evaluated by sweep net and sticky trap sampling. Environmental parameters such as light intensity, temperature and relative humidity were also recorded during the sampling to determine their possible range of influence towards the activity of the insect natural enemies. The Shannon-Wiener diversity index of insect natural enemies occurring on the C. cobanensis plant was 2.32. Among the dominant parasitoids observed on C. cobanensis plants are chalcids (Brachymeria lugubris and Brachymeria carinata) and braconids (Dolichogenidea metesae and Apanteles aluella), besides the reduuvid predator, Cosmolestes picticeps. In contrast, within the oil palm planting block, the undergrowth within the non-harvesting path only recorded a much lower diversity index of 1.09 and 1.12 each, in a block with C. cobanensis at the roadside and without, respectively. However, C. picticeps was shown to be much more dominant within both oil palm planting blocks, up to two- to three-fold, with much lesser numbers of hymenopterous parasitoids (less than five individuals). This indicates the important contribution of C. cobanensis plant towards enriching the diversity of the parasitoids, which are normally not found within the oil palm block, due to much less intense sunlight. In terms of insect activity, they are significantly more active in the moderate or medium light intensities (<8000 fc), medium humidity levels (50%-69%) and medium temperatures (30°C-34°C).

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* Malaysian Palm Oil Board, 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia.
E-mail: norman@mpob.gov.my