Starvation Levels Affect Behaviors of Wild-Caught and Laboratory-Reared Oil Palm Pollinator Weevil, Elaeidobius kamerunicus (Coleoptera: Curculionidae).

Abstract

Simple SummaryElaeidobius kamerunicus Faust (Coleoptera: Curculionidae) was introduced into Malaysia from Cameroon in 1981 to increase oil palm pollination. Fruit set development and fruit production significantly increased after the introduction, until a reported decline that began in the late 1980s. Several factors may have contributed to such a decline, including the weevil’s behavior. In this study, we evaluated the diurnal behavior of E. kamerunicus on different starvation level, sexes and sources of E. kamerunicus (wild-caught and lab-reared) through two hours of direct observation. The frequency and the time spent for each behavior, namely the flying (F), moving (M), feeding (E), resting (R), grooming (G) and mating (C) on oil palm flowers were recorded and evaluated. There were significant differences in flying, resting and grooming behavior among starvation levels. A similar result was demonstrated by sources of E. kamerunicus for resting, feeding and mating behavior. Wild-caught E. kamerunicus had a bigger size compared to laboratory-reared E. kamerunicus due to environmental and food source factors, which were limited and less variable for the reared type. Overall, our findings indicate that starvation level, sexes and sources of E. kamerunicus affect the diurnal behavior of E. kamerunicus.The oil palm pollinating weevil, Elaeidobius kamerunicus Faust (Coleoptera: Curculionidae) was first introduced into Malaysia from Cameroon as the main oil palm pollinator in 1981. Since then, oil palm pollination has improved and the need for assisted pollination has reduced. However, their pollinating behavior may be influenced by starvation, sexes and sources (wild-caught and lab-reared). A study to determine the effect of starvation level, sexes and sources of E. kamerunicus on their diurnal behavior was conducted utilizing two hours of direct observation between 1130 and 1330 h. The frequency and the time spent for several diurnal behaviors on oil palm flowers were recorded and evaluated. Starvation prevented the weevils from conducting the activities because they probably had to focus more on searching for food to gain energy to perform other behavior. Wild-caught and lab-reared E. kamerunicus differed in their size, while sexes of E. kamerunicus significantly affect the diurnal behavior. However, an in-depth study is needed to determine the relationship between the diurnal behavior of E. kamerunicus and oil palm production.