Demography and Population of Elaeidobius kamerunicus Faust (Coleoptera:Curculionidae) as a Pollinator of Oil Palm (Elaeis guineensis Jacq) in PT. Agri Andalas Plantation, Bengkulu Province

Abstract

Elaeidobius kamerunicus is an insect pollinator of oil palm. These weevil live and thrive in the male flowers of oil palm. The aims of the research were to study demography and population of E. kameunicus in male flower of oil palm. Demography study of the weevil were observed in the laboratory. One individual male and female of weevil were reared in the box, feeding by one spikelet of male flower. Observation of demographic study were conducted from 2nd day after rearing, until the weevil died. Populations of E. kamerunicus in oil palm plantations were measured by using a sampling method. We selected nine spikelet per bunch of male flower and counted the number of weevil per spikelet. The number of weevil per spikelet and number of spikelet per bunch were counted to determine the number of weevil per bunch. We counted the numbers of anthesis male flower per hectare to determine the number of weevil per hectare. Environmental parameters i.e temperature, humidity, light intensity, and rainfall were measured. The relationship between weevil population and environmental parameters were analyzed by Principal Component Analysis (PCA). Results showed that weevil E. kamerunicus tooks 14-17 days to grow from egg to imago. Statistics demography of the weevil were: generation time (T) was 19 days, gross reproduction rate (G) was 11 individuals, the net reproductive rate (Ro) was 5 individual and intrinsic growth rate (r) was 0.24. Population of the weevil on oil palm age 3 and 6 years were higher in January (41.102 individuals per hectare) and February (153.226 individuals per hectare). While, the lower population of the weevil were found in March (22.618 individuals per hectare) and April (98.693 individuals per hectare). In average, fruit set of oil palm age 3 and 6 years were 82,8% and 83,3%, respectively.

Kelapa sawit (Elaeis guneensis Jacq) merupakan tanaman komoditas yang sangat penting. Kelapa sawit tidak hanya digunakan sebagai bahan bakar industri, tetapi juga digunakan sebagai bahan baku dalam pembuatan sabun, obat-obatan, dan kosmetik. Kelapa sawit merupakan tanaman berumah satu (monoecious), namun bunga jantan dan bunga betina tumbuh secara terpisah, sehingga proses penyerbukan dibantu oleh agens penyerbuk. Serangga penyerbuk utama kelapa sawit adalah kumbang Elaeidobius kamerunicus. Kumbang tersebut mempunyai kemampuan penyerbukan lebih baik dibandingkan serangga lain. Kumbang tersebut hanya dapat makan dan berkembang biak pada bunga jantan kelapa sawit. Kumbang E. kamerunicus bersifat holometabola (metmorfosis sempurna), yaitu perkembangan dimulai dari telur, larva, pupa, dan imago. Populasi kumbang E. kamerunicus perlu dijaga dan ditingkatkan untuk menunjang produktivitas perkebunan kelapa sawit. Penelitian ini bertujuan untuk (1) Mempelajari demografi kumbang E. kamerunicu di laboratorium, (2) Mempelajari populasi kumbang E. kamerunicus sebagai penyerbuk kelapa sawit di perkebunan, dan (3) Mempelajari efektivitas populasi kumbang E. kamerunicus dalam penyerbukan, yang diukur dari buah yang terbentuk (fruit set).