Aspectos biológicos dos estádios imaturos de Chrysoperla externa (Hagen) e Ceraeochrysa cincta (Schneider) (Neuroptera: Chrysopidae) alimentados com ovos e ninfas de Bemisia tabaci (Gennadius) biótipo B (Hemiptera: Aleyrodidae)

Abstract

The biological aspects of immature stages of Chrysoperla externa (Hagen) and Ceraeochrysa cincta (Schneider) fed on eggs and nymphs of Bemisia tabaci (Genn.) biotype B were evaluated. Eggs of the predators were individualized into 2.5 cm in diameter and 8.5 cm tall flat bottom glass vials which were maintained 25±2°C temperature, 70±10% RH and 14h photophase. After larvae eclosion, 2 cm in diameter disks of tomato and cabbage leaves containing eggs and nymphs of B. tabaci, respectively, were then placed in the vials. Duration and viability of each larval instar as well as of the pupal phase of both predator species fed on different stage of the prey were evaluated. First- instar larvae of C. externa had longer development when fed on eggs of B. tabaci biotype B, thus showing that the stage of the prey offered did affect the developmental period. The same did not occur for C. cincta. The development of the 1st-instar larvae of both predator species was similar when fed on B. tabaci eggs; however, C. cincta presented a longer development period (5.4 days) as compared to C. externa (4.0 days) when fed on nymphs of the prey. For 2nd- and 3rd-instar larvae and for the duration of the larval phase there was no effect of the stage of the prey offered (egg or nymph) on the developmental period. The duration of the 2nd instar was longer for C. cincta than for C. externa (4.8 and 4.1 days, respectively). However the duration of the 3rd instar was longer and the larval phase was shorter for C. externa (6.6 and 15.3 days, respectively) than for C. cincta (6.4 and 16.7 days, respectively). The larval instars viability was above 90% for both species. Nevertheless, lower percent viability of the pupal phase was recorded for C. cincta, when fed on eggs (30%) or nymphs (55.6%).