BIOLOGICAL CONTROL OF ASPARAGUS BEETLE LARVAE (CRIOCERIS ASPARAGI) BY INSECT PARASITIC NEMATODES

Larvae of the asparagus beetle (Crioceris asparagi) were treated with four different nematode species. Trials were performed on whole asparagus (Asparagus officinalis) plants in an experimental greenhouse. The larvae were sprayed with a suspension of 2500 nematodes per ml, 250 ml/plant in total. After one week the treatment was repeated. For the different treatments, the final total reduction of the number of larvae was in ranked order: blank (33%), Heterorhabditis megidis (54%), Steinernema carpocapsae (58%), Heterorhabditis bacteriophora (66%) and Steinernema feltiae (96%). To assess the optimal dose for S. feltiae, concentrations of 625, 1250 and 2500 nematodes/ml were tested on asparagus beetle larvae. Mortality was 27, 85 and 92%, respectively. It was concluded that S. feltiae is a very promising biological control agent of asparagus beetle larvae. A dose of 1250 nematodes/ml seems to be most effective. Larger open field trials are recommended.