Characteristics of the Insulin-like Peptide Genes and Their Roles in the Ovarian Development of Zeugodacus cucurbitae (Coquillett)
1
Chongqing Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400715, China
2
Key Laboratory of Agricultural Biosafety and Green Production of Upper Yangtze River (Ministry of Education), Southwest University, Chongqing 400715, China
3
College of Life and Health Science, Kaili University, Kaili 556011, China
*
Authors to whom correspondence should be addressed.
Insects 2025, 16(8), 854; https://doi.org/10.3390/insects16080854
Submission received: 2 July 2025
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Revised: 13 August 2025
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Accepted: 13 August 2025
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Published: 17 August 2025
(This article belongs to the Section Insect Physiology, Reproduction and Development)
Simple Summary
Insulin-like peptides (ILPs), which function as hormones regulating essential physiological processes such as growth, development, and reproduction in insects, exhibit limitedly understood mechanisms of action in the reproductive regulation of agricultural pests. The melon fly, Zeugodacus cucurbitae (Coquillett), poses a significant threat to the secure global production of Cucurbitaceae crops. This study focuses on the biological functions of two ILP genes that are highly expressed in adult melon fly fat bodies, employing RNA interference (RNAi). Our results demonstrate that silencing these ILP genes significantly downregulates the transcription of key genes involved in ovarian development and the insulin signaling pathway (ISP). Furthermore, silencing the target genes led to decreased ovarian size in female flies, accompanied by a pronounced delay in developmental phenotype. This work highlights the critical role of these ILP genes in female melon fly reproduction, providing important molecular targets for developing novel RNAi-based pest control strategies.
Abstract
The melon fly Zeugodacus cucurbitae (Coquillett) is a globally invasive pest responsible for substantial economic losses in the fruit and vegetable industries. Insulin-like peptides (ILPs) are evolutionarily conserved neuropeptides that play a crucial role in insect reproduction. In this study, six ZcILPs from the melon fly, designated as ZcILP1–6, were cloned. Phylogenetic analysis demonstrated a strong orthologous link with Dipteran ILPs. Spatiotemporal expression profiling revealed that ZcILP1 and ZcILP3 exhibit preferential enrichment in the adult female fat body, with their expression specifically and significantly upregulated in 5-day-old individuals. Their expression decreased 12, 24, and 48 h post-starvation and increased upon re-feeding. Silencing ZcILP1 and ZcILP3 resulted in reduced ovarian size by 51.42% and 69.17%, respectively. Furthermore, silencing ZcILP1 or ZcILP3 significantly decreased the transcriptional levels of genes downstream of the insulin signaling pathway (ISP), notably the target of rapamycin (ZcTOR) and Forkhead box O (ZcFOXO). Concurrently, the expression of Vitellogenin (ZcVg), a gene associated with reproduction, was significantly downregulated. These findings indicate that ZcILP1 and ZcILP3 regulate ZcVgs expression and ovarian development through ISP, suggesting them as potential targets for green control of Z. cucurbitae.
