Aspectos biológicos de Chrysoperla externa (Hagen, 1861) (Neuroptera: Chrysopidae) alimentada com Bemisia tabaci (Gennadius, 1889) biótipo B (Hemiptera: Aleyrodidae) criada em três hospedeiros

Abstract

The aim was to study some biological aspects of adults of Chrysoperla externa (Hagen), from larvae fed on nymphs of third and fourth stages of Bemisia tabaci (Gennadius) biotype B, and reared on leaves of cucumber (Cucumis sativus), kale (Brassica oleracea) and wild poinsettia (Euphorbia heterophylla). Leaf discs from the hosts containing third and fourth stage nymphs of whitefly, were placed in Petri dishes containing 1% agar. One recently hatched larvae of C. externa was placed in each dish, until adult emergence. The weight after emergence,eoviposition, oviposition, effective oviposition and postoviposition periods, the total number of eggs per female and longevity were evaluated. The embryonic period and the survival rate of the eggs were also recorded by collecting weekly samples of 10% of the daily egg production, throughout the reproductive period. The weights of males and females did not differ in relation to the hosts, the average being 4.7 mg. In general, adults of C. externa, coming from larvae fed on B. tabaci biotype B nymphs reared on leaves of the host wild poinsettia, had their biological characters affected, in comparison with those on leaves of cucumber and kale. The oviposition period averaged 49.5 days for cucumber and kale, and 31.6 days for wild poinsettia. Egg laying capacity was reduced by 50% on wild poinsettia, its being 293.8 eggs. In cucumber and kale, the average was 591.3 eggs. Nymphs of B. tabaci biotype B reared on wild poinsettia caused increase of the embrionic period and a reduction of the survival rate of the eggs, its being 62.8% and 57.7% lower than that presented by the ones reared on cucumber and kale, respectively.