RESEARCH ARTICLE

Journal of Oil Palm Research Vol. 17 June 2005, p. 53-63

ENVIRONMENTAL FACTORS AFFECTING THE POPULATION DENSITY OF ORYCTES RHINOCEROS IN A ZERO-BURN OIL PALM REPLANT

NORMAN Kamarudin* ; MOHD BASRI Wahid* ; RAMLE Moslim*

ABSTRACT

The environment (abiotic and biotic factors) influences the survival of an organism. This study revealed several significant relationships between the population of Oryctes rhinoceros and the environment and physical characteristics of its habitat in an oil palm replant. Firstly, lower populations of O. rhinoceros occurred in areas with high cover crops over the decomposing chipped trunks. Secondly, high moisture content in the trunks was essential for the survival and satisfactory development of O. rhinoceros . Thirdly, there was a negative relationship between the number of developing pupae against the hardness of the trunk chips. This indicates that most of the pupae developed in the softer, decomposing chips. The larval population hastened the release of the trunk nutrients to the soil, especially K and Mg. Higher soil pH indirectly reduced the larval population of O. rhinoceros , possibly by promoting the growth of the entomopathogenic fungus, Metarhizium , which infected the larvae. This was reflected by the low number of adult beetles which emerged from the plots with high pH. Finally, rainfall induced the breeding of O. rhinoceros as shown by the high positive correlation between rainfall and the number of early instar larvae. Knowledge of some of these factors would enable planters to manipulate the habitat and its microclimate in order to manage the pest more effectively.

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* Malaysian Palm Oil Board,
P. O. Box 10620,
50720 Kuala Lumpur,
Malaysia.
E-mail: norman@mpob.gov.my