Laurel wilt is a destructive vascular disease responsible for high mortality of American tree species in the family Lauraceae, particularly redbay (Persea borbonia) and swampbay (P. palustris), two dominant components...Laurel wilt is a destructive vascular disease responsible for high mortality of American tree species in the family Lauraceae, particularly redbay (Persea borbonia) and swampbay (P. palustris), two dominant components of Coastal Plain forest communities in the southeastern United States. The disease syndrome emerged as a result of establishment of an exotic wood-boring beetle, Xyleborus glabratus, now known as the redbay ambrosia beetle. During gallery excavation, females of X. glabratus introduce a newly-described, obligatory fungal symbiont, Raffaelea lauricola. This fungus proliferates within the gallery and provides food for the beetles, but it has proven to be pathogenic to American lauraceous hosts, which have had no co-evolved history with R. lauricola. Presence of the foreign fungus elicits secretion of resins and formation of extensive parenchymal tyloses within xylem vessels. The extreme defensive response results in blockage of water transport, systemic wilt, and ultimately tree death. The beetle vector was first detected near Savannah, Georgia in 2002, and since has spread throughout the Southeast to become established in six states. The epidemic spread south through Florida more rapidly than predicted and currently threatens commercial production of avocado (Persea americana). Recent research indicates that California bay laurel (Umbellularia californica) can serve as a reproductive host for X. glabratus and is susceptible to laurel wilt disease. Thus, the US Pacific coastal forest ecosystems (and the California avocado industry) would be negatively impacted should the vector become established along the western coast. This review article summarizes our current understanding of the insect vector, the mycopathogen, and the susceptible host tree species. It also addresses elements of disease management and limitations with our current detection methods for redbay ambrosia beetle, which rely on manuka oil lures. Of the host-based attractants evaluated, cubeb oil shows the most promise as a potential new lure for X. glabratus.展开更多
Background In ambrosia and bark beetles–fungi interaction,volatile organic compounds(VOCs)play a central role in mediating various aspects of community dynamics of beetles and/or fungi.These functions include facilit...Background In ambrosia and bark beetles–fungi interaction,volatile organic compounds(VOCs)play a central role in mediating various aspects of community dynamics of beetles and/or fungi.These functions include facilitating beetle habitat location,mate identification,and fungal partner differentiation.However,the understanding on this context remains limited,especially in the globally distributed subfamily Platypodinae,which comprises predomi-nantly ambrosia beetles.There is a lack of chemical data on ambrosia fungi from native South American species.This study addresses this gap by characterizing VOCs from twelve fungal species associated with Megaplatypus mutatus and assessing species-specific behavioral responses during dispersal.Methods Fungal VOCs were collected by gas chromatography–mass spectrometry combined with solid-phase microextraction and Y-olfactometry assays of males and females were performed at dispersal stage.Statistical analyses involved:non-metric multidimensional scaling multivariate plot and PERMANOVA test,a cluster analysis through unweighted pair group method with Jaccard index,and finally,a chi-square goodness-of-fit test for beetle behavioral assays.Results We identified 72 VOCs from the fungal species isolated from M.mutatus galleries,exocuticle,and gut.The olfactory behavior of M.mutatus demonstrated its capacity to discriminate between volatile profiles,showing a pref-erence for either the fungus or the control source.Our results also enhance the understanding in a chemotaxonomic context and in the behavioral responses of M.mutatus revealing the beetle's remarkable low temperature toler-ance and its capability to maintain mobility and orientation toward volatile sources even after zero-degree Celsius exposure.Conclusion This study presents a comprehensive insight into fungal VOC profiles,emphasizing the sources of isola-tion within pest associated fungi,as well as its symbiotic species from the Raffaelea genus.In conclusion,our find-ings suggest that Megaplatypus mutatus exhibits a general aversion to its fungal VOCs symbiont.However,a notable exception arises when the beetles are pre-exposed for 48 h to freezing conditions,highlighting the beetles'ability to withstand freezing conditions as adults and to exhibit altered responses to their fungal associates under these circumstances.展开更多
文摘Laurel wilt is a destructive vascular disease responsible for high mortality of American tree species in the family Lauraceae, particularly redbay (Persea borbonia) and swampbay (P. palustris), two dominant components of Coastal Plain forest communities in the southeastern United States. The disease syndrome emerged as a result of establishment of an exotic wood-boring beetle, Xyleborus glabratus, now known as the redbay ambrosia beetle. During gallery excavation, females of X. glabratus introduce a newly-described, obligatory fungal symbiont, Raffaelea lauricola. This fungus proliferates within the gallery and provides food for the beetles, but it has proven to be pathogenic to American lauraceous hosts, which have had no co-evolved history with R. lauricola. Presence of the foreign fungus elicits secretion of resins and formation of extensive parenchymal tyloses within xylem vessels. The extreme defensive response results in blockage of water transport, systemic wilt, and ultimately tree death. The beetle vector was first detected near Savannah, Georgia in 2002, and since has spread throughout the Southeast to become established in six states. The epidemic spread south through Florida more rapidly than predicted and currently threatens commercial production of avocado (Persea americana). Recent research indicates that California bay laurel (Umbellularia californica) can serve as a reproductive host for X. glabratus and is susceptible to laurel wilt disease. Thus, the US Pacific coastal forest ecosystems (and the California avocado industry) would be negatively impacted should the vector become established along the western coast. This review article summarizes our current understanding of the insect vector, the mycopathogen, and the susceptible host tree species. It also addresses elements of disease management and limitations with our current detection methods for redbay ambrosia beetle, which rely on manuka oil lures. Of the host-based attractants evaluated, cubeb oil shows the most promise as a potential new lure for X. glabratus.
基金financially supported by Ministerio de Ciencia,Tecnología e Innovación from Argentina to ECN,CC and PGA with Grants IDs PICT-BID 2010-305,PICT-BID 2019-00100 and PIP 0956
文摘Background In ambrosia and bark beetles–fungi interaction,volatile organic compounds(VOCs)play a central role in mediating various aspects of community dynamics of beetles and/or fungi.These functions include facilitating beetle habitat location,mate identification,and fungal partner differentiation.However,the understanding on this context remains limited,especially in the globally distributed subfamily Platypodinae,which comprises predomi-nantly ambrosia beetles.There is a lack of chemical data on ambrosia fungi from native South American species.This study addresses this gap by characterizing VOCs from twelve fungal species associated with Megaplatypus mutatus and assessing species-specific behavioral responses during dispersal.Methods Fungal VOCs were collected by gas chromatography–mass spectrometry combined with solid-phase microextraction and Y-olfactometry assays of males and females were performed at dispersal stage.Statistical analyses involved:non-metric multidimensional scaling multivariate plot and PERMANOVA test,a cluster analysis through unweighted pair group method with Jaccard index,and finally,a chi-square goodness-of-fit test for beetle behavioral assays.Results We identified 72 VOCs from the fungal species isolated from M.mutatus galleries,exocuticle,and gut.The olfactory behavior of M.mutatus demonstrated its capacity to discriminate between volatile profiles,showing a pref-erence for either the fungus or the control source.Our results also enhance the understanding in a chemotaxonomic context and in the behavioral responses of M.mutatus revealing the beetle's remarkable low temperature toler-ance and its capability to maintain mobility and orientation toward volatile sources even after zero-degree Celsius exposure.Conclusion This study presents a comprehensive insight into fungal VOC profiles,emphasizing the sources of isola-tion within pest associated fungi,as well as its symbiotic species from the Raffaelea genus.In conclusion,our find-ings suggest that Megaplatypus mutatus exhibits a general aversion to its fungal VOCs symbiont.However,a notable exception arises when the beetles are pre-exposed for 48 h to freezing conditions,highlighting the beetles'ability to withstand freezing conditions as adults and to exhibit altered responses to their fungal associates under these circumstances.
