Abstract

Brown plant hopper (BPH), Nilaparvata lugens is a devastating insect pest of rice. Effective control measures are desperately needed. Entomopathogenic fungi, such as Beauveria and Metarhizium, have shown great potential for the management of some sucking pests. In this study, to explore alternative strategy for sustainable control of the pest population, 12 isolates of Beauveria and Metarhizium from sucking pests were bioassayed under the concentrated standard spray of 1 × 10⁸ conidia/ml in laboratory. The cumulative mortalities of adult ranged from 17.2 to 82.1%, 10 days after inoculation. The virulence among all tested isolates exhibited significant differences. The two most virulent isolates, M. flavoviride (Mf82) and M. anisopliae (Ma20) with cumulative mortalities of 82.1 and 65.4%, respectively, were selected to detect the virulence to gravid female, female and male of BPH with suspension of 1 × 10⁸ conidia/ml. The susceptible sequence was gravid female > female > male. Isolates of Beauveria and Metarhizium could infect eggs of BPH. The infected eggs shrunk in shape, then turned brown and eventually had outgrowths of the sprayed fungus when maintained under high moist conditions. The virulence of Mf82 to the eggs was the greatest, whose cumulative mortality was 60.8%, 10 days after inoculation. The most virulent isolate selected in this study, M. flavoviride (Mf82) is a promising candidate for microbial control of BPH.

Key words: Nilaparvata lugens, Beauveria, Metarhizium, virulence, biocontrol agents, eggs.