Electroantennographic responses of wild and laboratory-reared females of Xyleborus affinis and X. ferrugineus to ethanol and bark volatiles of three host-plant species

Authors: ROMERO, PATRICIA - Institute De Ecologia - Mexico; IBARRA, LUIS - Institute De Ecologia - Mexico; CARRILLO, DANIEL - University Of Florida; GUERRERO-ANALCO, JOSE - Institute De Ecologia - Mexico; Kendra, Paul; KIEL-MARTINEZ, ANA - Institute De Ecologia - Mexico; GUILLEN, LARISSA - Institute De Ecologia - Mexico

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2022
Publication Date: 7/21/2022
Citation: Romero, P., L.A. Ibarra-Juárez, D. Carrillo, J.A. Guerrero-Analco, P.E. Kendra, A.L. Kiel-Martínez, and L. Guillén. 2022. 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. Topic Issue: Frontiers in Chemical Ecology. Insects 13(7): 655.
DOI: https://doi.org/10.3390/insects13070655

Interpretive Summary: Ambrosia beetles are wood boring insects that have symbiotic relationships with fungi. The beetles Xyleborus affinis and Xyleborus ferrugeneus are known to spread the fungal pathogens that cause mango wilt and cacao wilt, respectively, in the tropical Americas. In addition, both beetles are secondary vectors of the laurel wilt pathogen lethal to avocado trees in Florida. As part of a program to develop lures for these pests, scientists from the Instituto de Ecologia (Veracruz, Mexico), University of Florida (Homestead), and USDA-ARS (Miami, FL) used electroantennography (EAG) to compare olfactory responses of lab-reared beetles versus wild-caught beetles to ethanol and odors from three host species. The results indicated there were no differences between test cohorts of X. ferrugineus; however, significantly stronger EAG responses were elicited with wild X. affinis as compared to lab-reared beetles. Results indicate that field-caught, host-seeking female ambrosia beetles are better suited for screening potential new attractants. These results will facilitate development of improved bioassays for identification of new attractants for pest ambrosia beetles.

Technical Abstract: Chemical ecology studies on ambrosia beetles are typically conducted with either wild or laboratory-reared females. Unlike with laboratory-reared insects, important aspects that potentially influence behavioral responses, like age, physiological state and life history, are unknown in wild females. In this study, we compared the electroantennographic (EAG) responses of laboratory-reared and wild X. affinis and X. ferrugineus females 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 comparable with laboratory-reared and wild X. ferrugineus, whereas wild female X. affinis exhibited higher EAG responses than laboratory-reared females. Ethanol elicited the strongest olfactory responses in both species, followed by B. simaruba at 48 h, and P. schiedeana at 24 and 48 h with X. ferrugineus. Volatile profiles varied among aged bark samples, with 3-carene and D-limonene predominant in B. simaruba, and a-copaene and a-cubebene abundant in P. schiedeana. Further studies are needed to determine the biological function of the B. simaruba and P. schiedeana terpenes on X. affinis and X. ferrugineus and their potential application for development of effective lures.