Feeding behavior of Frankliniella fusca on seedling cotton expressing Cry51Aa2.834_16 Bt toxin.

Background: Tobacco thrips, Frankliniella fusca (Hinds), is a pest of cotton. Currently, growers rely on neonicotinoid seed treatments to control F. fusca. However, the occurrence of neonicotinoid-resistant F. fusca populations has created new challenges for their management. Development of thrips-active Cry51Aa2.834_16 Bacillus thuringiensis (Bt) toxin expressed in MON 88702 cotton will be an important new tactic for thrips management. Previous studies have shown that MON 88702 causes limited mortality of F. fusca adults and larvae but reduces infestations on seedling cotton by suppressing oviposition from colonizing adults. This suggests that the toxin affects host preference of adult F. fusca. Knowledge of the effect of this trait on F. fusca feeding behavior provides a more complete understanding of MON 88702 activity. Using electropenetrography, we compared the feeding behaviors of adult F. fusca females on MON 88702 cotton and a non-Bt isoline cotton over 2 h. The number of probes, proportion of probes resulting in ingestion, total duration of ingestion, and duration of ingestion per event were measured.

Results: On MON 88702 seedlings, F. fusca probed and ingested fewer times than those on non-Bt cotton. Probes on MON 88702 were less likely to lead to ingestion than on non-Bt cotton. The total duration of ingestion and duration of ingestion per event did not differ between treatments.

Conclusion: The results show that MON 88702 has an antifeedant effect on F. fusca, which provides insight into behavioral responses driving MON 88702 aversion and anti-oviposition documented in previous studies. © 2020 Society of Chemical Industry.