Responses of Oil Palm Pollinator, Elaeidobius kamerunicus to Different Concentrations of Estragoles

Abstract

Elaeidobius kamerunicus is the main insect pollinator for oil palm (Elaeis guineensis) worldwide. One of the main reason E. kamerunicus attracted to oil palm inflorescences is estragole, a volatile organic compound released by the oil palm inflorescences during anthesis stage. However, the amount of estragole released from the oil palm inflorescence is varied due to the influence of abiotic and biotic factors and is seen to have an impact on E. kamerunicus pollination activity on the oil palm. To evaluate the responses of E. kamerunicus, different types (wild and reared) and sex (male and female) of E. kamerunicus were exposed to different concentrations (1, 5, 10, 30, 50, 70, 100, 150 and 200 ppm) of commercial estragole using four-arm olfactometer. Results showed that E. kamerunicus significantly preferred 100 ppm of estragole compared to other concentration (F = 139.81; d.f. = 9; P < 0.05). A significant interaction was also recorded between estragole concentrations and sexes of E. kamerunicus (F = 3.91; d.f. = 9; P < 0.05) where male E. kamerunicus was found to be more responsive to 100 ppm of estragole compared female E. kamerunicus. The E. kamerunicus responses to estragole is in line with the increase of estragole concentration up to 100 ppm. However, the response of E. kamerunicus was significantly decreased after the concentration value. The result of this study can be a good platform for future references since the estragole compound plays a significant role in oil palms flower pollination by E. kamerunicus. The factor of type and sexes of E. kamerunicus did not affect the preferences which indicated that E. kamerunicus reared in the laboratory have the potential to be released into the oil palm plantation area to overcome the problem of pollination.