Efficacy of conventional and carbon-nano-formulated insecticide seed treatments on the Hessian fly Mayetiola destructor (Diptera: Cecidomyiidae)

Abstract

The Hessian fly (HF, Mayetiola destructor, Say, Diptera: Cecidomyiidae) poses a significant threat to wheat production, causing yield losses and economic damage globally. Conventional management techniques, such as using resistant cultivars, planting at the best pest management planting date, and destroying volunteer wheat, are limited. There are currently no remedial management options for a HF infestation. Most available management practices must be implemented before or at planting. Seed treatments are effective preventive methods, but only for 30 days after planting (DAP), and have not been tested recently. This study assessed the effectiveness of conventional seed treatments against Hessian flies in the laboratory. Carbon nanotube (CNT)-based nano-imidacloprid formulations were also developed, and their effectiveness was evaluated in both wheat grown in laboratory and field settings. The evaluation of conventional neonicotinoid seed treatments in the laboratory showed that thiamethoxam (0.404 mg ai/g wheat seed) remained highly effective against HF larval infestations, while imidacloprid (0.9 mg ai/g wheat seed) resulted in moderate control. Nano-imidacloprid formulations, prepared by the suspension of imidacloprid with multi-walled carbon nanotubes (MWCNTs), demonstrated enhanced pesticidal activity. The high-rate nano-formulated imidacloprid (0.9 mg ai/g wheat seed) seed treatment significantly reduced HF infestations compared to the high-rate conventional imidacloprid (0.9 mg ai/g wheat seed) treatment, and the two controls (untreated and the CNT). The low-rate nano-formulated imidacloprid (0.9 mg ai/g wheat seed) seed treatment infestation was similar to the commercial imidacloprid (0.9 mg ai/g wheat seed) seed treatment infestation but significantly lower than the two controls. This suggests that insecticide seed treatments, formulated using nanotechnology, have the potential to serve as an effective alternative for managing the HF, with the added benefit of reducing overall environmental pesticide inputs, thereby promoting environmental sustainability.