Evaluation of entomopathogenic nematodes for control of the beetle, Luperomorpha suturalis Chen (Col., Chrysomelidae)

The strains Steinernema feltiae Otio and A54, Steinernema ceratophorum D43 and Steinernema carpocapsae BJ were tested for their infectivity to the larvae and pupae of beetle (Luperomorpha suturalis Chen) at 25+/-0.5degreesC and 15+/-0.5degreesC in laboratory conditions. The results, based on comparison of the insect mortalities and nematode penetration rates among four nematode strains, showed that S. feltiae Otio was a potential biocontrol agent of the larvae and pupae of L. suturalis . The mortalities of the larvae and pupae exposed to S. feltiae Otio strain were 95.8 and 97.1% at 25+/-0.5degreesC and 78.0 and 83.0% at 15+/-0.5degreesC, respectively. The nematode penetration rates of S. feltiae Otio of the larvae and pupae were 15.6 and 19.0% at 25+/-0.5degreesC, 2.6 and 6.3% at 15+/-0.5degreesC, respectively. Field efficacy of S. feltiae Otio strain was examined against beetle larvae in Hebei province, northern China. The population reduction of insect larvae was 77.8 and 13.9% at doses of 30 and 15 infective juveniles (IJs)/cm(2) of S. feltiae Otio after 38 days of treatment and 90.2 and 92.4% after 100 days of treatment. However, the population of the insect larvae was reduced only to 15.5 and 15.7% when treated with pesticide after 38 and 100 days, respectively. The efficiency between the two nematode doses was not significantly different but it was remarkably higher than that of the pesticide after 100 days of application. The results suggest that S. feltiae Otio strain could be an alternative to pesticide for beetle control.