Redox imbalance mediates entomotoxic effects of the conifer Araucaria angustifolia in Anticarsia gemmatalis velvetbean caterpillar

Abstract

The velvetbean caterpillar, Anticarsia gemmatalis is one of the most important pests of soybean crops in tropical America. By feeding on leaves, significant defoliation occurs resulting in reduced photosynthetic capacity required for plants’ maintenance and growth, which subsequently can lead to crop losses and reduced agricultural productivity. Many studies have sought to look for compounds that have insecticidal effects. One class of compounds is phenolics, which are produced by plants and have been found to influence the behavior and development of defoliators, representing an important alternative approach to many synthetic insecticides. Particularly, Araucaria angustifolia is a plant rich in polyphenols, which are compounds able to alter cellular dynamics through modulating redox status. In this study, A. angustifolia extract (AAE) was added to the artificial diet of A. gemmatalis. The results demonstrated that AAE was able to reduce larval viability by inducing morphological changes and a delay in the insect’s development. In addition, AAE was found to induce oxidative damage to lipids and proteins, as well as increased nitric oxide levels in A. gemmatalis larvae. AAE treatments also decreased the antioxidant defense systems, leading to a redox imbalance. The reduction in viability in A. gemmatalis was positively correlated with oxidative markers, suggesting that redox imbalance can lead to larvae’s death. These results suggest that AAE possess insecticidal potential through the mechanisms of action of altering cellular redox state. Though further studies are required to confirm this, our study nevertheless contributes to a better understanding of AAE’s mechanisms of action as potential biopesticides in pest management, opening new perspectives on the development of compounds with insecticidal action.