An insulin-like peptide mediates trehalose storage in the western tarnished plant bug, Lygus hesperus

Authors: MAZOLEWSKI, D - University Of Nevada; Hull, Jimmy; Brent, Colin; NUSS, ANDREW - University Of Nevada

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2025
Publication Date: 11/8/2025
Citation: Mazolewski, D., Hull, J.J., Brent, C.S., Nuss, A.B. 2025. An insulin-like peptide mediates trehalose storage in the western tarnished plant bug, Lygus hesperus. Journal of Insect Physiology. 167. Article 104885. https://doi.org/10.1016/j.jinsphys.2025.104885.
DOI: https://doi.org/10.1016/j.jinsphys.2025.104885

Interpretive Summary: Insulin-like peptides (ILPs) regulate multiple functions in invertebrates, including metabolism, reproduction, growth, immunity, behavior, diapause, and lifespan. Insulin signaling has been widely demonstrated as a signal for the cellular uptake of circulating hemolymph sugars, which in insects is principally trehalose. Although well studied and understood in fruitflies, this role in carbohydrate allocation remains poorly examined in pest insects that pose a risk to agricultural production. In this study, three ILPs identified in the western tarnished plant bug (Lygus hesperus) were characterized in terms of their expression profiles and functional roles in clearing hemolymph trehalose and the subsequent accumulation of glycogen. Despite concomitant expression of the three ILPs, impaired clearance of hemolymph trehalose was only observed following ILP2 knockdown and glycogen accumulation above background levels was only observed with ILP1 knockdown. This work demonstrates the hallmark functions of insulin signaling in the western tarnished plant bug and provides a foundation to explore other functions associated with LhILPs in this pest species.

Technical Abstract: Insulin signaling controls many physiological processes in insects, and it has a demonstrated role in cellular uptake of circulating sugars. Much of our understanding of insulin signaling was pioneered through the use of model insects selected for their ease of use in the lab. However, the continued improvement and reduced cost of high throughput genetic sequencing has enabled opportunities for the physiological study of less explored insect species. Lygus hesperus, the western tarnished plant bug, is a significant agricultural pest of numerous crops and recent efforts have focused on different molecular approaches for identifying new pest management strategies. In this work, three insulin like peptides (LhILP1, LhILP2, and LhILP3) were characterized from the transcriptome of L. hesperus. LhILP1 and LhILP2 structurally resemble classic insulin like peptides while LhILP3 resembles arthropod Insulin-like Growth Factors (aIGFs). All three LhILPs were primarily expressed in the head, and were observed throughout development. We examined their function by observing clearance rates of injected trehalose from the hemolymph in adult L. hesperus males following RNAi knockdown of the respective LhILPs. Untreated males cleared the trehalose within 6 h and showed a corresponding increase in glycogen content. While knockdown of LhILP1 did not appear to impact clearance rate, knockdown of LhILP2 prevented clearance of circulating trehalose and glycogen accumulation. Knockdown of LhILP3 also prevented trehalose clearance, but this appears to be influenced by co-knockdown of LhILP2, rather than a direct effect. Head ligation stopped the release of head-produced LhILPs, preventing the clearance of injected trehalose, a condition that could be rescued with co-injection of heterologous insulin. Stage-specific expression and mortality in LhILP RNAi insects suggest that LhILPs have multiple additional roles besides hemolymph carbohydrate homeostasis in L. hesperus that remain to be explored.