Natural regulation of white grub (Holotrichia sp: Scarabidae) by birds in agroecosystem.

ABSTRACT

The white grub (Holotrichia sp Scarabidae) is an important subterranean pest damaging root systems of several crops. Experiments conducted during I985 and I986 showed that at least I4 species of birds picked up the grubs exposed during ploughing operation. The important bird predators were mynas Acridotheres tristis (Linnaeus) and Acridotheres ginginianus (Latham), crows Corvus splendens (Vieillot), Corvus macrorhynchos (Sykes), drongo Dicrurus adsimilis (Hodgson) and cattle egret Bubulcus ibis. The birds were found to reduce 45 to 65% grub population during 3 subsequent ploughings. The plant stand of second crop raised in bird exposed field was higher in experimental plot compared to the control. The number of birds attracted to the plough was not consistent with the density of grubs exposed but oh many extraneous factors. Factors affecting the extent of bird predation were presence of insectivorous birds in the surroundings, proximity to their breeding sites and timing of ploughing. White grub control by birds is economically cheaper and environmentally safe compared to the chemical control.