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Abstracts - Natalia Ribas

Type of the Presentation: Poster

REPRODUCTIVE FITNESS COST OF CRY1FA RESISTANCE IN POPULATIONS OF Spodoptera frugiperda

Natalia Ribas1*, Bruna Ribas2 and Eraldo Lima3

1 UFV- Universidade Federal de Viçosa; natalia.sribas@gmail.com

2 UFV- Universidade Federal de Viçosa; bruna.dsribas@hotmail.com

3 UFV- Universidade Federal de Viçosa; eraldo.lima@gmail.com

* Correspondence: natalia.sribas@gmail.com

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is a major polyphagous pest in corn as well as in other crops. It has evolved resistance to transgenic Bt corn producing Cy1Fa which is the main strategy for its pest control. It has been shown that resistant insects to Bt toxins have higher development fitness cost than the susceptible ones. For example, resistant females of the moth Helicoverpa armigera had a more extended ovarian development when compared with susceptible females. Thus, there may be a fitness cost caused by the resistance. If the resistance has a high fitness cost for the insect, a non-Bt area (refuge) may play an essential role in favoring susceptible individuals. Here, we aimed to evaluate if there is a reproductive fitness cost in males of S. frugiperda. Since the spermatophore weight is correlated with their reproductive capacity, we used as a parameter for evaluation. We performed two experiments with both resistant and susceptible males which were individualized at the fourth hour of the scotophase and mated with resistant and susceptible virgin females, respectively. In the first experiment, virgin males of 3, 5 and 7 days-old were mated with virgin females of 3 days old. In the second, males of 3 days-old were mated with virgin females of 3 days-old; the same males were mated again in the fifth day-old with virgin females of 3 days-old and again on the seventh day with virgin females of 3 days old. We found that the weight of spermatophores for the susceptible males was heaviest than for the resistant males. These results suggest that there may be a reproductive fitness cost in resistant males of S. frugiperda.