Edge effects on ambrosia beetle assemblages in a lowland rain forest, bordering oil palm plantations, in Peninsular Malaysia.
Investigations were made on forest edge effects on ambrosia beetle assemblages in Pasoh Forest Reserve, a lowland rain forest in Peninsular Malaysia dominated by Shorea spp., which largely borders oil palm plantations (Elaeis guineensis) established in the 1970s. Species richness and composition of the ambrosia beetles (Scolytidae: Xyleborini) sampled with ethanol traps were not considerably changed along a gradient from the inner core area to the boundary of the forest (just inside the forest border adjacent to the oil palm plantation). However, a polyphagous species, Xylosandrus crassiusculus, consistently increased in numbers over this gradient, becoming being super-dominant at the boundary. It was as abundant in the surrounding oil palm plantation as at the forest boundary, consistent with the hypothesis that there is a large influx of X. crassiusculus from the oil palm plantation (where it breeds in fallen oil palm leaf stalks) to the reserved forest. The population may also, to a lesser extent, be enhanced by forest disturbance at the margin of the reserve.