Abstract

The melon fly, Zeugodacus cucurbitae Coquillett (Diptera: Tephritidae), is a notorious quarantine pest. It poses a significant risk to fruits and vegetables in tropical and subtropical regions, affecting crops like cucumber, zucchini, muskmelon, bitter gourd and pumpkin. The rapid development of insecticide resistance necessitates the alternative strategies to manage this pest. RNA interference (RNAi) offers a promising and innovative approach for controlling major agricultural insect pests and has recently been approved for use in controlling the Leptinotarsa decemlineata. In this study, the essential gene, coatomer complex subunit gamma (γZcCOPI), was assessed as RNAi target using an oral feeding delivery method. γZcCOPI was most abundant in eggs and 2nd instar larvae in developmental stage dependent expression analysis, while tissue vise expression showed its highest expression in larval midgut. Exposure of Z. cucurbitae to the corresponding dsRNA of γZcCOPI significantly reduced gene expression leads to larval melanisation and larval-pupal transition delay. Additionally, adults that emerged from γZcCOPI knockdown larvae exhibited spotless wings, reduced phenoloxidase (PO) activity, and increased susceptibility to β-Cypermethrin exposure. These results demonstrated novel role of γZcCOPI in insects development and regulation of innate immunity, offering a promising target for insect pests management through RNAi.  

Key Words: Insecticide resistance, Immune system, Melon fly, Developmental abnormalities, RNA interference (RNAi).