Abstract
Propylea japonica (Thunberg) (Coleoptera: Coccinellidae) is a prevalent pollen consumer in corn fields and is therefore exposed to insecticidal proteins contained in the pollen of insect-resistant transgenic corn cultivars expressing Cry proteins derived from Bacillus thuringiensis (Bt). In the present study, the potential effect of Cry1Ab/2Aj- or Cry1Ac-containing transgenic Bt corn pollen on the fitness of P. japonica larvae was evaluated. The results show that the larval developmental time was significantly shorter when P. japonica larvae were fed pollen from Bt corn cultivars rather than control pollen but that pupation rate, eclosion rate, and adult fresh weight were not significantly affected. In the feeding experiments, the stability of the Cry proteins in the food sources was confirmed. When Bt corn pollen passed through the gut of P. japonica, 23% of Cry1Ab/2Aj was digested. The results demonstrate that consumption of Bt corn pollen containing Cry1Ab/2Aj or Cry1Ac has no detrimental effect on P. japonica larvae; the shortened developmental time of larvae that consumed these proteins was likely attributable to unknown differences in the nutritional composition between the Bt-transgenic and control corn pollen.
Highlights
The ladybird beetle, Propylea japonica (Thunberg) (Coleoptera: Coccinellidae), is a common and abundant natural predator in many crop and non-crop systems throughout East Asia[19,20,21]
Over 70% of the P. japonica larvae that exclusively consumed corn pollen developed to adults, and the percentage did not differ for larvae that fed on Bt corn pollen vs. those that fed on the corresponding control pollen (χ 2-test; both P > 0.05) (Table 1)
Results from the pollen consumption assay in the current study indicated that the P. japonica larvae readily accepted and utilized corn pollen
Summary
The ladybird beetle, Propylea japonica (Thunberg) (Coleoptera: Coccinellidae), is a common and abundant natural predator in many crop and non-crop systems throughout East Asia[19,20,21]. Both larvae and adults of P. japonica are predaceous, feeding predominantly on aphids but, on planthoppers, whiteflies, and eggs and young larvae of lepidopterans[22,23]. We investigated the potential effects of consumption of Bt corn pollen containing Cry1Ab/2Aj or Cry1Ac protein on P. japonica larvae in the laboratory
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