Evaluation of spring and autumn applied insecticides for the control of black beetle

Abstract

Black beetle (Heteronychus arator) is a sporadic but serious pest of North Island pastures Field trials were established to test the efficacy of insecticides currently registered for use against scarab pests in pasture Three life stages were targeted newly emerged black beetle adults in autumn egglaying adults in spring and newly hatched larvae in early summer Although the insecticides used caused significant beetle mortalities in spring no treatment reduced the subsequent larval populations in summer Similarly while the autumn application caused significant beetle mortality; the number of surviving black beetle adults remaining in the plots was not affected Soil factors and the high mobility of adult beetles are likely to have contributed to treatment failure