Muffled olfactory and sensory cues from the reproductive stage soybean selectively reduce oviposition of a major polyphagous herbivore, fall armyworm (Spodoptera frugiperda).

Background: While the mother knows best/preference performance hypothesis has been well tested in natural ecosystems, how these ecological principles differ in agroecosystems is less explored. In this study, we investigated the ovipositional preference and offspring performance of fall armyworm (FAW) across vegetative and reproductive stages of soybean.

Results: We examined trichomes, volatile organic compounds (VOCs) and assessed electroantennogram (EAG) measurements to understand how olfactory responses are affected by volatiles at different phenological stages during photoperiodism (photophase and scotophase). We found that gravid FAW preferred the vegetative compared to reproductive stage of soybean. Although VOC and EAG responses was not statistically different (P > 0.05) between photophase and scotophase, but vegetative stage exhibited significantly (P ≤ 0.05) higher emissions and responses than the reproductive stage during both photophase and scotophase. Additionally, reproductive stage had lower trichomes compared to the vegetative stage. Interestingly, no significant difference was observed in offspring performance between the vegetative and reproductive stages of soybean. This suggests that oviposition preference does not necessarily correlate with offspring performance, which was confirmed through offspring mass and mass gain studies. Olfactory and sensory cues from soybean at reproductive stage reduced oviposition by mother FAW.

Conclusion: Collectively, we show that while mother knows best may not fit FAW-Soybean interaction, muffled volatile emission in reproductive stages can have positive consequences for host success. The results from this study will enhance our understanding of FAW behavior across different phenological stages of host plants, that can be used to develop alternative and sustainable management strategies. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.