Impact of genetically modified potato expressing plant-derived insect resistance genes on the predatory bug Podisus maculiventris (Heteroptera: Pentatomidae)

The effects of the transgene proteins Galanthus nivalis agglutinin (GNA) and cowpea trypsin inhibitor (CpTI) on the predatory stinkbug Podisus maculiventris were studied under laboratory conditions. When the P. maculiventris were provided with tomato moth ( L. oleracea) larvae injected with either GNA or CpTI at a dose of 10 mug day(-1), growth was significantly reduced and, as a consequence, female adult weight was also significantly reduced. For GNA-fed and CpTI-fed P. maculiventris, this weight reduction was 11.3 and 16.6%, respectively. Males, however, were not significantly affected. Female bugs that had not been exposed to the transgene proteins as nymphs, however, showed no reduction in fecundity when these adults were provided with prey injected with either GNA or CpTI at this same dose. When provided with hosts that had been reared on transgenic plants expressing either GNA or CpTI, no effects on the survival of nymphs were observed and only small, largely non-significant, reductions in weights were recorded throughout preadult development. Male nymphs fed on the GNA-fed prey did, however, exhibit a significant lengthening of preadult development of 0.8 days. The subsequent adults showed significantly reduced egg production for the GNA treatment. The results indicate that P. maculiventris may suffer some indirect adverse effects from foraging for prey in crops expressing either GNA or CpTI, due to prey being of inferior quality, rather than to direct toxicity of the transgene products themselves.