The toxic effect of camphor vapour against Aphis craccivora Koch (Hemiptera: Aphididae) and some of its natural enemies

Abstract

Fumigant toxicity of camphor was studied against the aphid Aphis craccivora Koch and three associated natural enemies, i.e. Coccinella undecimpunctata L., Aphelinus albipodus Hayat & Fatima and Aphidius colemani Viereck. Aphis craccivora was the most tolerant one compared with all tested natural enemies as the recorded LC50 values were 12.71, 6.33, 1.16 and 0.48 mg camphor/liter space for the above mentioned insects, respectively. Subjecting newly emerged adults of A. craccivora to LC25 of camphor vapor significantly reduced female longevity from 17.6 to 6.45 days and reduced the female daily progeny from 4.44 to 1.93 nymph / female, which resulted in a reduction in productivity as finite rate of increase decreased from 1.57 to 1.14 female / female / day. Aphids that survived after subjection to LC50 were found to have significantly higher amount of acid phosphatase and G. S-transferase than non-treated aphids. Inversely, Survived aphids were found to have significantly less amount of β-esterases and alkaline phosphatase than nontreated aphids; while no significant difference was found in case of α-esterases. Camphor fumigant can be a candidate as a control agent against A. craccivora but with restriction because of its drawbacks on natural enemies.