Unraveling host selection in Chrysobothris: Stress cues, cultivar resistance, and future directions in buprestid ecology

Understanding host selection in Chrysobothris spp., a cryptic and economically significant group of wood-boring beetles, remains a key challenge in ornamental nursery systems. Though traditionally considered generalists, emerging evidence suggests species-level host preferences within the C. femorata complex, particularly among red maple cultivars. Field and phytochemical studies indicate that Chrysobothris are more likely to oviposit on red maple cultivars subjected to herbicide-induced stress—especially Scythe® (pelargonic acid)—while largely avoiding the hybrid cultivar ‘Autumn Blaze.’ Phytochemical shifts, including reductions in polyphenols and alterations in sugar concentrations, appear to be cultivar- and herbicide-specific and may act as host location cues. Our recent work supports the sequential cues hypothesis, showing that Chrysobothris may respond to a combination of visual (e.g., color) and chemical cues (e.g., VOCs, phenolic profiles) in selecting suitable oviposition sites. Notably, a 2024 field study demonstrated an additive effect of visual and chemical cues: trees that were both herbicide-stressed and visually altered attracted larval survival than either treatment alone. Despite advances, behavioral and physiological barriers limit lab-based research, including difficulty rearing adults and eliciting oviposition. Current greenhouse trials suggest that female oviposition may require environmental or physiological triggers absent in lab-reared individuals. Drawing from analogies in related Buprestids, we hypothesize that critical pre-oviposition behaviors or environmental factors may be missing. Future work aims to dissect long- and short-range host cues, evaluate cultivar resistance mechanisms, and explore mate-selection behaviors in Chrysobothris. These efforts are essential for improving integrated pest management and advancing our understanding of host specificity in wood-boring beetles.