Tritrofic interactions between Bt cotton plants, the aphid Aphis gossypii Glover, 1827 (Hemiptera: Aphididae), and the predator, Chrysoperla externa (Hagen, 1861) (Neuroptera: Chrysopidae)

Abstract

This research examined the effects of the Cry1Ac toxin on the chrysopid predator Chrysoperla externa, fed Ashbya gossypii-aphids reared on cotton (Bt) NuOPAL and non-Bt DeltaOPAL (Bollgard TM) for two generations. Individual eggs from the predator were placed in glass containers, and hatched. Each treatment consisted of 20 replicates, each containing one insect. Larvae in treatment 1 were fed A. gossypii individuals reared on a diet of NuOPAL (Bt) cotton leaves. Larvae in treatment 2 were given aphids of the same species previously fed leaves of conventional DeltaOPAL cotton. The average duration of larval instars, pre-pupal and pupal phases from both treatments (Bt and non-Bt) and between generations were evaluated using the t test at 5% probability. The duration of the larval instars in treatment 2 was longer than in treatment 1, but these differences were significant only for the second and third instars. In the second generation, a significant difference in the duration of the first instar and the larval phase were observed. However, when comparing the data on the duration of the second instar, the first generation predators in treatment 1 had a shorter lifespan. The average viability was 96.29% for non-Bt treatment against 91.07% for individuals in the Bt treatment. The results of this study suggests that the biology and development of C. externa larvae fed aphids reared on Bt cotton leaves were not affected by the Bttoxin, possibly because these aphids do not accumulate the Bt-toxin.

Influência da alimentação de Anagasta kuehniella Zeller(Lepidoptera: Pyralidae) no desenvolvimento de Ceraeochrysa cubana Hagen (Neuroptera: Chrysopidae)

“…Há possibilidade de proteínas Cry não fornecerem um efeito tritrófico, não comprometendo o desenvolvimento desses insetos, como já foi observado para outros indivíduos não alvo (Mendes et al 2012;leite et al 2014). Alimentos com presença de proteína Bt não afetaram a sobrevivência das fases imaturas e adultas de algumas espécies de crisopídeos (lawo et al 2010;Mota et al 2012;tian et al 2013). Vale salientar que as proteínas inseticidas não são claramente identificadas em farinhas comercializadas, nesse contexto, estudos mais detalhados são necessários.…”

Effects of Nitrogenous Fertilization and some Insecticides on the Natural Enemies of Transgenic Bt Cotton Pests

“…In laboratory experiments, Mota et al (2012) found that the biology and development of Chrysoperla externa Hagen (Neuroptera: Chrysopidae) larvae fed on Aphis gossypii Glover (Hemiptera: Aphididae) reared on leaves of Bt cotton were not affected by Cry1Ac toxin, possibly because these aphids do not tend to accumulate the Bt-toxin.…”