The effects of triazophos on the trehalose content, trehalase activity and their gene expression in the brown planthopper Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

A previous study demonstrated that the flight capacity of Nilaparvata lugens adults treated with triazophos was enhanced significantly. However, the physiological and regulative mechanisms of the flight enhancement are not well understood. Trehalose is a primary blood sugar in insects, and the enzyme trehalase is involved in energy metabolism. The present study investigated the effects of triazophos on the trehalose content, trehalase activity (soluble trehalase and membrane-bound trehalase) and the mRNA transcript levels of their corresponding genes (NlTre-1 and NlTre-2) in fifth instar nymphs, as well as in the brachypterous and macropterous N. lugens adult females. Our findings showed that the trehalose content in fifth instar nymphs as well as in the brachypterous and the macropterous adults significantly decreased following triazophos treatment. However, the glucose content, soluble trehalase activity and expression level of NlTre-1 mRNA increased significantly compared to the controls. No significant enhancement of NlTre-2 expression was found, indicating that regulation of energy metabolism of triazophos-induced flight capacity in N. lugens was not associated with NlTre-2 expression. In addition, soluble trehalase activity and the expression level of NlTre-1 mRNA in the macropterous females was significantly higher than that in the brachypterous females. The present findings provide valuable information on the molecular and regulative mechanisms of the increased flight capacity found in adult N. lugens after treatment with triazophos.