Electroantennographic Responses of Wild and Laboratory-Reared Females of Xyleborus affinis Eichhoff and Xyleborus ferrugineus (Fabricius) (Coleoptera: Curculionidae: Scolytinae) to Ethanol and Bark Volatiles of Three Host-Plant Species

Abstract

Chemical ecology studies on ambrosia beetles are typically conducted with either wild or laboratory-reared specimens. Unlike laboratory-reared insects, important aspects that potentially influence behavioral responses, such as age, physiological state, and prior experience are unknown in wild specimens. In this study, we compared the electroantennographic (EAG) responses of laboratory-reared and wild X. affinis and X. ferrugineus to 70% ethanol and bark odors (host kairomones) of Bursera simaruba, Mangifera indica, and Persea schiedeana aged for 2, 24, and 48 h. Chemical analyses of each odor treatment (bark species x length of aging) were performed to determine their volatilome composition. EAG responses were different between laboratory-reared and wild X. ferrugineus when exposed to ethanol, whereas wild X. affinis exhibited similar EAG responses to the laboratory-reared insects. Ethanol elicited the strongest olfactory responses in both species. Among the bark-odors, the highest responses were triggered by B. simaruba at 48 h in X. affinis, and P. schiedeana at 24 and 48 h in X. ferrugineus. Volatile profiles varied among aged bark samples; 3-carene and limonene were predominant in B. simaruba, whereas α-copaene and α-cubebene were abundant in P. schiedeana. Further studies are needed to determine the biological function of B. simaruba and P. schiedeana terpenes on X. affinis and X. ferrugineus, and their potential application for the development of effective lures.

Risk assessment of Hass avocado and Mexican Lauraceae for attack by redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae)

“…Despite the lack of consensus between beetle attraction and PCA/HCA using all volatiles detected at >2%, the four most attractive species-P. humilis, P. schiedeana, P. americana 'Hass', and O. heribertoi vel aff.-did share similarities in their volatile profiles. α-Copaene was a major compound (by percent composition) emitted by all four species, and α-cubebene was a major constituent emitted by P. americana 'Hass' and P. schiedeana (consistent with a recent analysis, Romero et al, 2022). Since there is a proximo-distal gradient in terpenoid distribution throughout a host tree, emissions of α-cubebene and α-copaene would be much higher in the trunk and large diameter branches (than in the small diameter branches assayed here), thereby directing host-seeking females to the optimal sites for colonization (Niogret et al, 2013).…”

Ligand-binding properties of XaffOBP9, a Minus-C odorant-binding protein from Xyleborus affinis (Coleoptera: Curculionidae: Scolytinae)

“…Electroantennogram (EAG) responses of female X. affinis to host plant volatiles have also been recorded, with essential oil extract from Leptospermum scoparium and Phoebe porosa , as well as silkbay wood of P. humilis, eliciting EAG responses in X. affinis ( Hanula and Sullivan, 2008 ). Another study compared the EAG responses of laboratory-reared and wild X. affinis to host kairomones of Bursera simaruba , Mangifera indica , and Persea schiedeana , with the highest responses being triggered by Bursera simaruba at 48 h in X. affinis ( Romero et al, 2022 ). The volatile profiles of aged bark samples, including compounds such as (-)-β-pinene, sabinene, ɑ-pinene, myrcene, camphene, 3-carene, m-cymene, (S)-(-)-limonene, ɑ-copaene, and terpinolene, varied.…”

Ambrosia beetles (Coleoptera: Curculionidae) can directly transmit the fungal pathogens responsible for Rapid ʻŌhiʻa Death

“…Other Ceratocystis pathogens have been associated with direct transmission by bark and ambrosia beetles such as Euwallacea interjectus (Curculionidae: Scolytinae) of Japanese Fig Ceratocystis canker (Kajii et al, 2013; Kajitani, 1996), Hypocryphalus mangiferae (Curculionidae: Scolytinae) of mango sudden decline (Al Adawi et al, 2013), and Platypus cylindrus (Platypodinae) of canker stain of plane (Soulioti et al, 2015). Xyleborus affinis has been implicated as a secondary vector of Ceratocystis fimbriata (Galdino et al, 2016; Romero et al, 2022; Souza et al, 2013) and Xyleborus ferrugineus a vector of Ceratocystis cacaofunesta (Goitía & Rosales, 2001; Romero et al, 2022; Saunders et al, 1967), although Leach's rules have yet to be met for these species.…”