Kairomonal Effects of Different Host Body Washings on Parasitism by Trichogramma brasiliensis and T. japonicum

Abstract

Bioassays were carried out in Petri dishes with body washings of larvae, male and female moths and scale extract of Corcyra cephalonica St. in hexane to observe their kairomonal effect on Trichogramma brasiliensis (Ashmead) and T. japonicum Ashmead. The mean parasitoid activity index (PAI) and mean parasitisation were recorded. Trichogramma brasiliensis and T. japonicum recorded the highest mean parasitisation in the eggs treated with scale extract. Mean parasitisation recorded by T. japonicum in cards treated with female moth and male moth body washings were considerably lower than the corresponding values for T. brasiliensis . Both the parasitoids recorded significantly lower levels of parasitisation in cards treated with larval body washings. Gas chromatographs of host body washings / extract recorded a large number of similar hydrocarbons in the body washings of male and female moths and the scale extract. Pentadecane, heneicosane, eicosane, tetracosane, pentacosane and hexacosane were recorded in scale extracts. Female moth body washings recorded the presence of eicosane, tetracosane and pentacosane while heneicosane and eicosane were indicated in the male moth body washings.