Volatile and Cuticular Chemical Profiling and Antennal Dose-Responses in Leptoglossus chilensis (Hemiptera: Coreidae)

Leptoglossus chilensis is a native South American coreid bug of economic and quarantine relevance whose chemical ecology remains undescribed. In this exploratory study, we characterised adult volatile and cuticular chemistry using dynamic headspace sampling (DHS), cuticular wash (CW), solid-phase microextraction (SPME), supercritical fluid extraction (SFE), and quantified electroantennographic (EAG) dose-responses in males and females in relation to a panel of eight literature-informed compounds (hexanal, hexyl acetate, hexyl formate, β-caryophyllene, (E)-β-farnesene, ocimene, benzyl alcohol and 2-phenylethanol). EAG responses were evaluated at six concentrations using a Bayesian hierarchical four-parameter Hill model. Across the four methods, 128 compounds were detected, of which 69 met a ≥20% detection-frequency threshold and were retained as the representative profile. Of these, hexanal, hexyl acetate, hexyl formate, and β-caryophyllene were detected in L. chilensis extracts, the latter only in male DHS collections; this compound is more likely to be a host plant volatile than an insect-produced signal. All eight compounds elicited concentration-dependent antennal responses in both sexes. Among these four compounds, β-caryophyllene yielded the lowest fitted EC₅₀ in both females (9 µg mL^-1 [90% CrI: 5-16]) and males (9 µg mL^-1 [90% CrI: 5-15]), although curves remained unsaturated; because delivered antennal dose was not measured and volatility differs substantially among the tested compounds, this cannot be interpreted as evidence of greater antennal sensitivity to β-caryophyllene specifically, and cross-compound EC₅₀ comparisons throughout this study are restricted to this caveat. All four Hill parameters were identifiable in both sexes for benzyl alcohol, (E)-β-farnesene, hexyl formate, and 2-phenylethanol. These results provide the first chemical and peripheral olfactory reference for L. chilensis and identify targets for behavioural and field evaluation.