Development of the predator Eocanthecona furcellata on different proportions of nucleopolyhedrovirus infected Spodoptera litura larvae and potential for predator dissemination of virus in the field

Abstract

The present work aimed to determine the impact of nucleopolyhedrovirus (NPV) on the development of Eocanthecona furcellata Wolff and to measure the infectivity of NPV discharged through its faeces. Developmental time, survival rate, sex ratio and incubation period of the predator reared on different proportions of healthy and NPV infected S. litura larvae as lifetime meal did not vary significantly. However, when the proportion of infected prey in the predator’s lifetime meal exceeded 50 % significant reductions in body weight, fecundity, longevity and percent egg hatchability were noticed. The virus did not show detrimental effect on the developmental biology of the predator in the subsequent generations when offspring emerging from nymphs fed only on virus infected prey throughout their life were reared on 50 % of infected prey. Therefore, adverse effects on E. furcellata are unlikely in the field as the predator is not expected to consume more than 50 % of infected prey even if the virus application is done at recommended dose. Under field conditions, it was found that increased proportions of infected prey enhanced the dissemination of viral inoculum through the faeces of the predators and the subsequent infection in S. litura larvae ranged from 22 to 52 %.