# Toxicity and Residual Effect of Toxic Baits on Adults of Spodoptera frugiperda (Lepidoptera: Noctuidae): Implications for Pest Management

## TL;DR

This study shows that toxic baits using Noctovi® 43SB and insecticides like methomyl and spinosad effectively kill and control the fall armyworm for up to 30 days.

## Contribution

The study introduces effective toxic bait formulations with high residual activity for managing insecticide-resistant S. frugiperda.

## Key findings

- Toxic baits with Noctovi® 43SB and insecticides achieved over 90% mortality in S. frugiperda adults.
- Methomyl, spinetoram, spinosad, and indoxacarb maintained over 70% mortality for 30 days.
- Toxic baits reduce insecticide use and help preserve biodiversity and susceptible pest populations.

## Abstract

Spodoptera frugiperda is considered a major pest in commodity production systems (soybean, maize, and cotton), causing severe economic losses. The main management tools rely on the use of synthetic insecticides and Bt crops. However, their frequent use has led to resistance issues and reduced control efficacy. To overcome these challenges, new management strategies based on behavioral control (attract-and-kill) have been investigated. This study evaluated synthetic insecticides in toxic bait formulations and their residual activity against adult S. frugiperda. The results showed that the food attractant Noctovi® 43SB combined with the insecticides methomyl, spinetoram, spinosad, and indoxacarb achieved mortality rates above 90%. In addition, the tested insecticides exhibited high residual activity, maintaining mortality rates above 70%, even 30 days after application. The use of attract-and-kill management strategies proved to be promising, providing high pest mortality and extended residual activity. Furthermore, toxic bait formulations allow for reduced insecticide use in cultivated areas, while also contributing to the maintenance of susceptible individuals and local biodiversity.

Spodoptera frugiperda is a major agricultural pest both in Brazil and worldwide, with widespread resistance to synthetic insecticides. This study evaluated the toxicity and residual activity of toxic bait formulations combining 17 insecticides with the plant-based kairomone attractant Noctovi® 43SB against S. frugiperda adults. Bioassays were conducted with 48 h-old, food-deprived adults. Toxicity was assessed by incorporating insecticides at 2% concentration into Noctovi® 43SB. Residual activity was measured by applying toxic baits on cotton leaves and testing at 3, 7, 15, 21, and 30 days after application (DAA). Insecticides based on methomyl, spinetoram, spinosad, indoxacarb, malathion, and zeta-cypermethrin induced over 95% mortality. Methomyl showed the greatest toxicity (LC50 = 322 mg a.i. L−1; LC90 = 1160 mg a.i. L−1). Eleven insecticides maintained residual activity (≥70%) after 30 DAA, except malathion. Overall, toxic bait formulations combining Noctovi® 43SB with methomyl, spinosad, spinetoram, or indoxacarb proved highly effective, offering both rapid and prolonged control of S. frugiperda adults. These findings highlight attract-and-kill as a promising tool for sustainable management of this pest.