Journal of Oil Palm Research Vol. 22 (1) April 2010, p. 758-764 NORMAN Kamarudin* ; MOHD BASRI Wahid*
Bagworms are one of the important leaf-eating pests of oil palm in Malaysia and Indonesia, causing high yield losses up to 43% over two years after a serious infestation. Parasitoids and predators play an important role in regulating bagworm numbers. The propagation and establishment of the natural enemies depend on some suitable species of flowering plants as sources of nectar. Cassia cobanensis, a leguminous nectar producing plant is recommended to be grown in oil palm plantations as a food source for parasitoids related to the bagworm. An observation on the interactions of the bagworm pest and its natural enemies was conducted at an oil palm plantation in Perak, Malaysia. A bagworm (Pteroma pendula) infested block, with C. cobanensis planted along the roadside, and a control block with no C. cobanensis within their vicinity, were chosen for the trial. In late 2006, the population of the bagworms increased to 60 live larvae per frond (LPF) in the control block, while in the C. cobanensis block it remained below 30 LPF. A chemical control operation in early 2007 reduced the population of bagworms to negligible levels for about two years. The natural enemies (predators and parasitoids) were monitored using sticky traps and sweep nets in all the plots. Results show that due to the negligible bagworm hosts in the block, activities of the insect parasitoids shifted to the C. cobanensis plants planted along the roadsides. In the control block, the natural enemies still dwelt within the ground covers because of the absence of C. cobanensis plants in the vicinity. Activities of predators were seen to be more prominent on ferns while parasitoids preferred to dwell on plants with nectar sources (C. cobanensis and Asystasia gangetica). These observations strongly suggest the importance of establishing C. cobanensis within the vicinity of oil palm plantations in order to sustain the population of natural enemies for long-term control of bagworms.KEYWORDS:
* Malaysian Palm Oil Board,
P. O. Box 10620,
50720 Kuala Lumpur, Malaysia.