Toxicity of several insecticides to Dichromothrips smithi Zimmermann(Thysanoptera : Thripidae)

This study was carried out to investigate the toxicities of 22 insecticides to Dichromothrips smithi. Insecticidal activity was evaluated by testing systemic action and residual effect in laboratory. All insecticides used in this study did not affect on the egg of D. smithi, although organophosphates such as fenitrothion, fenthion, methidathion, phenthoate, and phenthoate+ethofenprox suppressed the egg hatchability completely. On D. smithi larva fenitrothion, fenthion, methidathion, phenthoate, ethofenprox, thiamethoxam, abamectin, chlorfenapyr, emamectin benzoate, fipronil, spinosad, and phenthoate+ethofenprox showed 100% insecticidal activity. On D. smithi adult fenitrothion, fenthion, methidathion, phenthoate, ethofenprox, abamectin, emamectin benzoate, fipronil, spinosad, and phenthoate+ethofenprox showed 100% insecticidal activity. Root-uptake systemic effects of phenthoate on the larva of D. smithi was 43.3%. Whereas, systemic effect of other insecticides was less than 20%. Insecticide with more than 80% residual effect for 7 days after treatment were fenitrothion, fenthion, methidathion, phenthoate, ethofenprox, emamectin benzoate, fipronil, spinosad, and phenthoate.