Toxicity of selected agrichemicals to clover root weevil and its parasitoid Microctonus aethiopoides

Abstract

White clover (Trifolium repens) crops are attacked by various insect pests including Sitona obsoletus (S lepidus) (CRW) Laboratory experiments were conducted to measure the toxicity of eight agrichemicals used against white clover insect pests or for weed control on CRW (parasitised and nonparasitised) and adults of its parasitoid Microctonus aethiopoides Laboratory experiments evaluated insect toxicity through direct contact with the agrichemical spray or via exposure to residues on clover foliage At field rates pymetrozine had the lowest impact on CRW biocontrol but had poor activity against nonparasitised CRW Taufluvalinate provided 60 control of CRW while having reduced impact on M aethiopoides adults (060 mortality) and was considered the best option in the field over the summer period Lambdacyhalothrin and diazinon were the most detrimental to CRW and its biocontrol agent when applied directly and through exposure to residues Diquat and an adjuvant caused some mortality to CRW and parasitoid Field studies are needed to corroborate these results