A SURVEY ON DEFOLIATION AND PHYTOPHAGOUS INSECTS IN FOUR HABITAT TYPES IN SABAH, MALAYSIA

Abstract

The degree of defoliation in four different habitat types (primary forest, logged forest, acacia plantation and oil palm plantation) was investigated. Logged forest was most severely defoliated in terms of absolute leaf area eaten, percentage of leaf area eaten and number of holes. This was attributed to the many fastgrowing and short-lived tree species in the logged forest which were more palatable to the phytophagous insects. Phytophagous Coleoptera were more speciose and abundant in the forests compared with the plantations. Oil palm plantation recorded fewer Orthoptera compared with other sites. There were significant positive relationships between the abundance of Coleoptera and Orthoptera with the percentage of leaf area eaten. A significant positive relationship was also observed between the Coleoptera abundance and the number of holes on leaves. In this study, Coleoptera were the best predictor of defoliation compared with lepidopteran larvae and Orthoptera.