Autodissemination of insecticides applied to agricultural pests: Spodoptera frugiperda's role in generating toxicity on its offspring

This work examined whether Spodoptera frugiperda adults can pick up pyriproxyfen from an insecticide-treated surface and transfer it to their egg masses through autodissemination, inducing toxicity in newly hatched larvae upon ingestion. We also assessed pyriproxyfen distribution on egg masses during oviposition and its transfer from males to virgin females during mating. The lethal and sublethal toxicity of pyriproxyfen was evaluated through two bioassays: one on autodissemination (transfer to egg masses) and another simulating the effect of transferred doses to the egg masses. Pyriproxyfen amounts in adults and egg masses were analyzed using gas chromatography-mass spectrometry (GC-MS). Gravid females picked up the most pyriproxyfen (9.45 μg/insect), followed by males (7.67 μg/insect) and virgin females (3.30 μg/insect). Besides, gravid females transferred an average 2.61 ng/egg to their egg masses. In the autodissemination bioassay, larval emergence, pupation and adult emergence were reduced, while larval development was delayed. These findings were confirmed by the toxicity assay simulating the transferred doses. We also observed pyriproxyfen transfer from males to virgin females during mating. The results suggest that Spodoptera frugiperda gravid females can transfer pyriproxyfen to egg masses, causing toxicity in larvae, highlighting the potential of autodissemination as an alternative or complementary pest control method.