RESUMEN
The use of neurotoxic chemical insecticides has led to consequences against the environment, insect resistances and side-effects on non-target organisms. In this context, we developed a novel strategy to optimize insecticide efficacy while reducing doses. It is based on nanoencapsulation of a pyrethroid insecticide, deltamethrin, used as synergistic agent, combined with a non-encapsulated oxadiazine (indoxacarb). In this case, the synergistic agent is used to increase insecticide efficacy by activation of calcium-dependant intracellular signaling pathways involved in the regulation of the membrane target of insecticides. In contrast to permethrin (pyrethroid type I), we report that deltamethrin (pyrethroid type II) produces an increase in intracellular calcium concentration in insect neurons through the reverse Na/Ca exchanger. The resulting intracellular calcium rise rendered voltage-gated sodium channels more sensitive to lower concentration of the indoxacarb metabolite DCJW. Based on these findings, in vivo studies were performed on the cockroach Periplaneta americana and mortality rates were measured at 24â¯h, 48â¯h and 72â¯h after treatments. Comparative studies of the toxicity between indoxacarb alone and indoxacarb combined with deltamethrin or nanoencapsulated deltamethrin (LNC-deltamethrin), indicated that LNC-deltamethrin potentiated the effect of indoxacarb. We also demonstrated that nanoencapsulation protected deltamethrin from esterase-induced enzymatic degradation and led to optimize indoxacarb efficacy while reducing doses. Moreover, our results clearly showed the benefit of using LNC-deltamethrin rather than piperonyl butoxide and deltamethrin in combination commonly used in formulation. This innovative strategy offers promise for increasing insecticide efficacy while reducing both doses and side effects on non-target organisms.
Asunto(s)
Calcio/metabolismo , Insecticidas/química , Insecticidas/farmacología , Nanocápsulas/química , Nitrilos/química , Nitrilos/farmacología , Oxazinas/química , Oxazinas/farmacología , Piretrinas/química , Piretrinas/farmacología , Animales , Células Cultivadas , Cucarachas , Masculino , Estructura Molecular , Periplaneta/efectos de los fármacos , Intercambiador de Sodio-Calcio/metabolismoRESUMEN
Integrated Pest Management and Integrated Vector Management worldwide are developed in agriculture and public health to counteract and limit the exponential increasing development of insect resistance to insecticides. However, facing the predominance of some resistant populations, new strategies are urgently needed to target resistant insects. An innovative approach lies in the optimization of commonly used insecticides when combined with chemical or biological synergistic agents. By an increase of intracellular calcium concentration followed by activation of calcium-dependant signalling pathways, the synergistic agents are able to indirectly increase target sites sensitivity to insecticide by inducing conformational change. The synergistic agents are of great interest in optimizing the efficacy of insecticides and in overcoming resistance mechanisms.