Assessment of Nano-Formulated Conventional Insecticide-Treated Sugar Baits on Mosquito Control and the Effect on Non-Target Aphidophagous Coccinella septempunctata

Abstract

Mosquitoes, as disease vectors causing global morbidity and mortality through diseases like malaria, dengue, and Zika, necessitate mosquito population control methods. This study investigated the efficacy of nano-formulated insecticide-based sugar baits in controlling Anopheles gambiae populations and assessed their potential non-target impact on Coccinella septempunctata. This laboratory-based study employed thiolated polymer-coated attractive toxic sugar bait (ATSB) nano-formulations, delivering pesticides via nano-carriers. Adult and larvae populations of insects were collected from rice and cotton fields subjected to bioassays with 0.5% and 1% concentrations of each nano-formulated and conventional insecticide within ATSB solution, alongside a control 100% attractive sugar bait (ASB). Mosquitoes interacted overnight with insecticide-treated baits, and mortality was assessed. Further observations up to 72 h were conducted for potential delayed toxic effects. Results highlighted nano-ATSB carbosulfan's effectiveness, particularly among organophosphates and pyrethroids. Among pyrethroids, nano-ATSB cypermethrin exhibited high efficacy, while Deltamethrin displayed lower mortality. Among organophosphates, nano-ATSB chlorpyrifos induced substantial mortality. The nano-formulations of insecticide were harmless against C. septempunctata compared to their conventional form. Nano-formulations demonstrated enhanced mortality rates and prolonged efficacy against mosquitoes, having a benign impact on non-target beetles. We expect these results to aid in developing effective plant protection products suitable for IPM practices.

Keywords: Coccinella septempunctata; attractive toxic sugar baits; mosquito; nano-formulated conventional insecticides; vector-borne diseases.

Figure 1

Mean mortality comparison of N-ATSB and ATSB pyrethroid applications against An. gambiae: (a) lambda-cyhalothrin, (b) cypermethrin, (c) deltamethrin, (d) bifenthrin. The graphs’ bars represent the mean values of three replicates, and lowercase letters denote significant differences between treatments at p < 0.05. T₁ included ASB (100%), T₂ featured a 0.5% insecticide concentration + 99.50% ATSB, T₃ utilized a 1% insecticide concentration + 99% ATSB, T₄ employed a 0.5% nano-formulated insecticide concentration + 99.50% ATSB, and T₅ applied a 1% nano-formulated insecticide concentration + 99% ATSB.

Figure 2

Mean mortality comparison of N-ATSB and ATSB organophosphate applications against An. gambiae: (a) triazofos, (b) profenofos, (c) chlorpyrifos. The graphs’ bars represent the mean values of three replicates, and lowercase letters denote significant differences between treatments at p < 0.05. T₁ included ASB (100%), T₂ featured a 0.5% insecticide concentration + 99.50% ATSB, T₃ utilized a 1% insecticide concentration + 99% ATSB, T₄ employed a 0.5% nano-formulated insecticide concentration + 99.50% ATSB, and T₅ applied a 1% nano-formulated insecticide concentration + 99% ATSB.

Figure 3

Mean mortality comparison of N-ATSB and ATSB carbamate applications against An. gambiae: (a) carbosulfan, (b) propoxur, (c) methomyl. The graphs’ bars represent the mean values of three replicates, and lowercase letters denote significant differences between treatments at p < 0.05. T₁ included ASB (100%), T₂ featured a 0.5% insecticide concentration + 99.50% ATSB, T₃ utilized a 1% insecticide concentration + 99% ATSB, T₄ employed a 0.5% nano-formulated insecticide concentration + 99.50% ATSB, and T₅ applied a 1% nano-formulated insecticide concentration + 99% ATSB.