Journal of Oil Palm Research Vol. 13 No. 1, June 2001, p. 64-74 NORMAN Kamaruddin* ; ZAIDI Mohd Isa** ; MAIMON Abdullah** ; MOHD BASRI Wahid*
A laboratory study was conducted to evaluate the factors which affected larval development in four different substrates commonly found in the oil palm replanting environment. The percent survivorship of Oryctes rhinoceros was lowest in raw empty fruit bunches (EFB), followed by coconut trunk (CT) and oil palm trunk (OPT). Processed EFB and oil palm fronds (OPF) were found to be less suitable substrates, as indicated by the incomplete development of the larval stages. There were lower percentage of nitrogen in the OPF (0.45%) and EFB (0.35%), compared to CT (1.98%) and OPT (0.56%) substrates, which could have affected the duration for each developing stage. The higher starch content in OPT compared to raw EFB may also have influenced the development of the larvae. The weights of almost all the developing stages were higher in CT substrate. The second and third larval instars had consumption rates of 2.2 g day-1 and 4.1 g day-1 of CT and OPT substrates respectively. Although the consumption rates were higher in OPT, the weight of larvae remained significantly lower (p<0.05) than in CT. There was a significant linear relationship (p<0.001) between the percent moisture content and weight of the third instar larvae, showing water to be an important factor in ensuring weight increase in the larval and subsequently, pupal stages. Moisture content of 77% and above was essential for the complete development of 0. rhinoceros. It is hoped that this information will lead to a modification of the zero burn replanting practice, so as to create less suitable environments for the beetle to breed in, thus avoiding the risk of 0. rhinoceros attack.KEYWORDS:
*Malaysia Palm Oil Board, PO Box 10620,50720 Kuala Lumpur, Malaysia.
** Faculty of Science and Technology, Universiti Kebangsaan Malaysia,43600 UKM, Bangi Selangor, Malaysia.