Sublethal effects of potato plant defenses induced via synthetic elicitors against the Colorado potato beetle (Coleoptera: Chrysomelidae)

Leptinotarsa decemlineata (Say) is among the most destructive insect pests of potato Solanum tuberosum L. worldwide. While conventional chemical tactics have repeatedly failed to control this pest due to the rapid development of resistance, elicitor-based enhancement of plant defenses using jasmonic acid (JA) or salicylic acid (SA) pathways offers a promising complementary approach. Hence, this study evaluated the effects of 3 commercially available plant defense elicitors: Blush 2X (JA type), Actigard 50WG (SA type), and Regalia (JA and SA type), on the growth, development, and performance of L. decemlineata larvae across 2 phenological stages of "Russet Burbank" potatoes, with and without Myzus persicae (Sulzer) co-infestation. Defoliation, larval development, weight, and excretion rates were assessed through a series of greenhouse bioassays. Blush 2X significantly reduced defoliation and delayed larval development, supporting the role of JA signaling in mediating antifeedant defenses. In contrast, high-rate Actigard 50WG increased defoliation and excretion while reducing larval weight, suggesting altered sugar allocation and a potential diuretic effect. Aphid presence induced signal interference, modifying elicitor efficacy in a plant stage-dependent manner. These findings highlight the potential of elicitor treatments to enhance integrated pest management strategies for L. decemlineata, while underscoring the importance of plant phenology, signal cross-talk, and ecological context in optimizing their deployment.