Using Azadirachtin to Transform <i>Spodoptera frugiperda</i> from Pest to Natural Enemy

• Published in: Toxins
• Main Authors: Sukun Lin, Shengnan Li, Zhenghui Liu, Li Zhang, Hao Wu, Dongmei Cheng, Zhixiang Zhang
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Subjects: azadirachtin; maize; <i>Spodoptera frugiperda</i>; <i>Rhopalosiphum maidis</i>; natural enemy; pest control
• Online Access: https://www.mdpi.com/2072-6651/13/8/541

<i>Spodoptera frugiperda</i> and <i>Rhopalosiphum maidis</i>, as main pests, seriously harm the safety of maize. At present, chemical pesticides are mainly used to control these pests. However, due to residue and resistance problems, more green, environmentally benign, simple preventive control technology is needed. In this study, we reported the reason for the antifeedant activity of azadirachtin on <i>S. frugiperda</i> and proposed that <i>S. frugiperda</i> treated with azadirachtin would turn from pest into natural enemy. <i>S. frugiperda</i> showed an obvious antifeeding phenomenon to maize leaf treated with various azadirachtin concentrations (0.5~20 mg/L). It was found that maize leaf treated with 1 mg/L of azadirachtin has a stimulating effect on the antenna and sensillum basiconicum of <i>S. frugiperda</i>, and azadirachtin can affect the feeding behavior of <i>S. frugiperda</i>. Additionally, after treating maize leaves or maize leaves + <i>R. maidis</i> with 1 mg/L of azadirachtin, the predatory behavior of <i>S. frugiperda</i> changed from a preference for eating maize leaves to <i>R. maidis</i>. Moreover, the molting of <i>R. maidis</i> can promote the change of this predatory behavior. Our results, for the first time, propose that the combined control technology of azadirachtin insecticide and biological control could turn <i>S. frugiperda</i> from pest into natural enemy, which can effectively eliminate <i>R. maidis</i> and protect maize. This combined control technology provides a new way for pest management and has good ecological, environmental, and economic benefits.