Ontogenesis of Aldehyde Pheromones in Two Synanthropic Bed Bug Species (Heteroptera: Cimicidae)

SIMPLE SUMMARY: The common (Cimex lectularius) and tropical (C. hemipterus) bed bugs are widespread blood-feeding human pests. To better understand their chemical ecology, the current study quantified the four most abundant bed bug aldehydes in the bed bugs’ immature stages by extracting their freshly shed exuviae. We also quantified the two most abundant aldehydes in adult bed bugs via surface extraction. Quantitative comparisons are made across different developmental stages (nymph), species (nymph and adult), or sexes (adult). In immature bed bugs, significant quantitative differences of four aldehydes were found across developmental stages within a species, and between species within a stage. Similarly, in adult bed bugs, a significant difference in the ratio of (E)-2-hexenal and (E)-2-octenal was found between species. This study provides the first systematic quantification of these aldehydes for all five of the nymphal stages for both C. lectularius and C. hemipterus. ABSTRACT: Bed bugs produce volatile aldehydes that have alarm and aggregation functions. Using two synanthropic bed bug species, Cimex lectularius L. and C. hemipterus (Fabricius), developmental changes were examined for (E)-2-hexenal, 4-oxo-(E)-2-hexenal, (E)-2-octenal, and 4-oxo-(E)-2-octenal, the four most abundant aldehydes shared between the two species. Quantitative analyses of the aldehydes in the nymphal exuviae indicated that the aldehydes’ ratio remained similar throughout nymphal development. In general, (E)-2-octenal was most abundant, and (E)-2-hexenal and 4-oxo-(E)-2-octenal were least abundant. The fourth aldehyde, 4-oxo-(E)-2-hexenal, was present in intermediate quantities. The quantities and percent abundances of the aldehydes in nymphal exuviae and the adults were significantly different between C. lectularius and C. hemipterus. The ratio between (E)-2-hexenal and (E)-2-octenal was determined in adult male and female bed bugs of each species. Adult C. hemipterus had a higher proportion of (E)-2-hexenal than C. lectularius, while no sex differences were found. This work provides the first systematic quantification of four aldehydes [(E)-2-hexenal, 4-oxo-(E)-2-hexenal, (E)-2-octenal and 4-oxo-(E)-2-octenal] for all five of the nymphal stages for both C. lectularius and C. hemipterus.