Efficiency of three formulated entomopathogenic nematodes against onion thrips, thrips tabaci under aquaculture system

Abstract

Entomopathogenic nematodes (EPN) proved to be efficient control agents against thrips under soil stages. However, few studies were reported on foliar application of EPNs against the feeding stages which cause the initial infestation. Therefore, the aim of this study was to evaluate the efficacy of three formulated parasitic nematodes, two native and an adapted exotic species, against the onion thrips, Thrips tabaci L., under green house conditions in aquaculture. The nematode species were in vivo produced using larvae of the greater wax moth. Nematodes were formulated using mixed polymer based on calcium alginate and their viability was tested before each application. The experiment was done inside the greenhouse on onion plants heavily infested with onion thrips, T. tabasi. Population density of the pest was estimated before and after spraying with the tested bioformulated EPNs. EPNs species caused significantly higher mortality than control treatment in different developmental stages of T. tabaci. In general the three formulated nematodes, BA1, BA2 and OBIII had significantly better shelf-lives than the control. Data showed that S. carpocapsae BA2, was the most commonly applied species for control of foliar pests. They are ideal candidates for pest insects that are encountered on the surface soil when they descend from foliage. The market of EPNs-based biopesticides has faced great success in relation to few marketing failures during the past two decades. Due to the rapid increase in EPNs production technology, their prices become more compatible to other insect control strategies. Therefore, the development of simple; cheap and innovative formulations should not only target increasing EPNs performance but also enhancing storage ability and application methods.