Effects of phytocompound Precocene 1 on the expression and functionality of the P450 gene in λ-cyhalothrin-resistant Spodoptera litura (Fab.)

Abstract

Spodoptera litura(Fabricius) is an agriculturally significant polyphagous insect pest that has evolved a high level of resistance to conventional insecticides. A dietary assay was used in this work to assess the resilience of field populations ofS. liturato λ-cyhalothrin. Analysis of the function and expression of the cytochrome P450 gene was used to test the sensitivity ofS. lituralarvae to sub-lethal concentrations of the insecticidal plant chemical Precocene 1, both by itself and in combination with λ-cyhalothrin. The activity of esterase enzymes (α and β) was found to decrease 48 h post treatment with Precocene 1. The activity of GST enzyme and cytochrome P450 increased with Precocene 1 treatment post 48 h, however. Expression studies revealed the modulation by Precocene 1 of cytochrome P450 genes,CYP4M16,CYP4M15,CYP4S8V4,CYP4G31, andCYP4L10. WhileCYP4M16expression was stimulated the most by the synergistic Precocene 1 + λ–cyhalothrin treatment, expression ofCYP4G31was the most down-regulated by Precocene 1 exposure. Hence, it is evident that λ–cyhalothrin-resistant pest populations are still sensitive to Precocene 1 at a sublethal concentration that is nevertheless capable of hindering their development. Precocene 1 can therefore be considered a potent candidate for the effective management of insecticide-resilientS. litura.