Preliminary Study on Entomopathogens for White Grub Management in Nepal

Abstract

White grubs are increasingly important pests of cereal and cash crops in Nepal. The situation is further aggravated for their management due to their high level resistance to insecticides, as an alternative method of management. To overcome this problem, an insect pathogenic fungal- based antagonists are coming out. Series of activities were conducted since the mid of 2002 at Tribhuvan University, Institute of Agriculture and Animal Sciences (IAAS), Rampur and in farmers' fields in Nepal. Several dozens of isolates of the insect pathogenic fungi, Metarhizium anisopliae (green muscardine fungus) and more than half a dozen of Beauveria bassiana (white muscardine fungus) were recovered from infested soil and diseased insects by using a selective medium and the Galleria bait method (GBM). Isolation, maintenance, mass production and efficacy tests of M. anisopliae were conducted under captivity. A three-tier screening strategies; exploration of the indigenous fungal based bioagents, screening of the virulence under captivity and field tests were initiated with M. anisopliae. With the preliminary screening, four isolates namely, M1, M6, M18 and M48 being identified as pathogenic for insect pest larva (Maladera sp.) at concentrations of 10⁵ and 10⁷ spores/ml. Mass production in barley kernels was achieved into autoclavable polybags, however, field tests are under way in different locations of farmers field in Nepal.

J. Inst. Agric. Anim. Sci. 25:39-46