Influence of posttreatment temperature on the toxicity of fenvalerate

Posttreantment temperature effects on the toxicity of fenvalerate (α-cyano-3-ohenoxy-benzyl-2-(4-chlorophenyl)-isovalerate) and othe insecticides were assessed. Fenvalerate, pyrethrins and DDT were from 2.5 to 7.3 time more toxic to Spodoptera litura larvae at 15°C than at 25°C by topical application method and foliar dipping method. As for salithion and methomyl LD50 values by topical application method were not affected by the posttreatment temperature, but the insecticidal activities by foliar dipping method showed a positive temperature coefficient. Fenvalerate, pyrethrins and DDT also showed a negative temperature coefficient of paralysing effect against S. litura, knockdown activity against Laodelphax striatellus and lethal activity against Plutella xylostella.