Location: Subtropical Horticulture ResearchTitle: Life cycle, development, and culture of Xyleborus glabratus (Coleoptera: Curculionidae: Scolytinae) Author
Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2013
Publication Date: 9/19/2013
Citation: Brar, G., Capinera, J.L., Kendra, P.E., Mclean, S., Pena, J.E. 2013. Life cycle, development, and culture of Xyleborus glabratus (Coleoptera: Curculionidae: Scolytinae). Florida Entomologist.96(3): 1158-1167. Interpretive Summary: The redbay ambrosia beetle (Xyleborus glabratus) is a wood-boring pest that transmits laurel wilt, a lethal disease of trees in the plant family Lauraceae, including avocado and native forest species. Despite several years of research on this newly-established pest, no effective and economical means of control have been identified. Management of the disease will require a holistic approach, which depends on a better understanding of the insect vector. Scientists from the University of Florida, in collaboration with an entomologist from the USDA-ARS Subtropical Horticulture Research Station (Miami, FL), conducted research to document the basic biology of X. glabratus. This work included (1) establishing laboratory rearing methods for the beetle, (2) describing its gallery formation patterns in host trees, and (3) recording the stages of its development in its three primary hosts: avocado, redbay, and swampbay. Results showed that rate of development was similar in all three hosts, but fewer offspring were produced in avocado wood, suggesting that avocado is a less suitable reproductive host than native bay trees. In addition, it was shown that females can lay eggs over a very long time-span. After initial infestation of a tree, new beetles emerge in about two months, and emergence can continue for eight months or longer. This information will be used by scientists and action agencies to develop integrated pest management programs for this new invasive pest.
Technical Abstract: The redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), is a wood-boring pest that transmits the fungal pathogen Raffaelea lauricola, the causal agent of laurel wilt disease in American Lauraceae. This study documents the gallery formation patterns of X. glabratus as well as its life cycle and development at 25±2° C in logs of three natural hosts: avocado (Persea americana), redbay (P. borbonia) and swampbay (P. palustris). Females were observed to excavate galleries perpendicular to the tree trunk; galleries were characterized by a main entrance tunnel, from which branched secondary tunnels that, in turn, gave rise to tertiary tunnels. By dissecting infested logs daily, the length of time was determined for each developmental stage, and found to be comparable in all three hosts. Eggs were first encountered in avocado, redbay, and swampbay at 7, 11, and 10 d after gallery initiation (agi), respectively; larvae at 14, 20, and 14 d agi; pupae at 24, 26, and 26 d agi; and teneral adults at 31, 30, and 27 d agi. Despite comparable rates of development in all hosts, there were fewer progeny per female produced in avocado. Oviposition by the founding female extended over a broad time-span, and all stages were observed in the gallery at one month agi. Three larval instars were present, with mean head capsule widths of 0.21, 0.26, and 0.37 mm, respectively. Long term rearing of X. glabratus was achieved on swampbay logs soaked in water prior to infestation. Emergence of new females from logs was first observed at 60 d agi, indicating that teneral adults remain in hosts for ~1 month prior to dispersal. Emergence continued for up to 240 d, with maximum emergence observed between 120-150 days agi.