Entomopathogenic nematode biocontrol of striped flea beetle larvae: A novel methodology for efficacy testing

Striped flea beetle (Phyllotreta striolata) is a major worldwide pest, particularly for canola and other cruciferous crops. These insects provide a challenge for laboratory testing due to the difficulty of maintaining a colony in captivity. However, laboratory assays are crucial to evaluate new methods of flea beetle control. Control methods currently available to growers include chemical seed treatments and foliar sprays, but these methods, if used alone, can lead to insecticide-resistant populations. Biocontrol methods include natural enemies like parasitic wasps and other beetles, but these provide minimal control. However, entomopathogenic nematodes (EPNs) show promising results when used to control flea beetle larvae. Adult flea beetles can cause devastating damage to young plants, while larvae cause little damage to plants, so larval control measures can be used to reduce the population of new generations in a field before they begin to cause crop damage. For this study, new methodologies were developed for testing flea beetle larvae in a laboratory. Results showed that Steinernema carpocapsae, when applied at rates of 250 million, 500 million, and 750 million nematodes per acre, to radish plants infested with striped flea beetle larvae, led to a reduction in subsequent leaf damage after a month by 71%, 81%, and 95%, respectively.