TOXICITY OF RAPESEED MEAL-AMENDED SOIL TO WIREWORMS, LIMONIUS-CALIFORNICUS (COLEOPTERA, ELATERIDAE)

The acute toxicity of soil amended with rapeseed (Brassica napus L.) s eed meal to wireworms, Limonius californicus (Mannerheim) (Coleoptera: Elateridae), was determined in laboratory bioassays. Wireworms were e xposed to rapeseed seed meal at concentrations from 41.7-500 g/kg soil for 24 h. Probit analysis estimated a LC(50) value of 124.8 g/kg soil 7 d after treatment. The LC(50) value decreased to 114.4 g/kg soil 21 d after treatment with no further change in mortality up to 35 d. Bra ssica napus tissues show potential for reducing populations of L. cali fornicus. However, applications to soil for insect pest management wou ld require plant material with even higher levels of isothiocyanate-pr oducing glucosinolate to provide useful biological fumigation activity .