Interaction effects of entomopathogenic nematodes and insecticides for the management of grubs of Holotrichia longipennis and Brahmina coriacea

ABSTRACT

Aim: Laboratory studies were conducted to study the potential of entomopathogenic nematodes and their interaction with the commonly used insecticides viz., clothianidin, imidacloprid and chlorpyriphos against first, second and third instar grubs of H. longipennis and B. coriacea.Methodology: Two entomopathogenic nematodes viz., Heterorhabditis indica Poinar and Steinernema caprocapsae Weiser were tested against I-III instar grubs of Brahmina coriacea (Hope) and Holotrichia longipennis (Blanchard) under laboratory conditions @1600IJs per cup by soil application. The mortality data was recorded after every 24 hrs up to 5 days. For evaluating the interaction effects among different tested biocontrol agents with insecticides, each entomopathogenic nematode species and insecticides was tested alone and in combination. H. indica and S. carpocapsae were applied @ 400IJs per cup. Insecticides were applied at a lower concentrations viz. 150, 100 and 75 ppm for chlorpyriphos, imidacloprid and clothianidin, respectively and were applied on the same day of nematode application with a gap of 2 hrs. Mortality data was taken after 24 hrs. Results: Individual application of H. indica and S. carpocapsae @1600 IJs per cup had clearly lethal effect and produced mortality to the tune of 55.5-90.7 % in both the species of white grubs. H. indica revealed higher virulence as compared to S. carpocapsae against both the species. Combination of both the species with all the tested insecticides yielded synergistic interactions and H. indica+ imidacloprid combination proved to be the most promising among all the tested combinations. Interpretation: Tested entomopathogens and insecticide combination produced synergistic interactions more effectively to first, second and early third instar grubs (H. longipennis and B. coriacea).