Temperature-dependent development of redbay ambrosia beetle (Xyleborus glabratus Eichoff) and its symbiotic fungi Raffaelea lauricola

Redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae) beetle is nonnative pest that vectors the pathogenic fungus Raffaelea lauricola.  Raffaelea lauricola causes a vascular wilt disease known as laurel wilt in trees of family Lauraceae. Redbay (Persea borbonia) and swampbay (Persea palustris)  trees are the two ecologically important trees of the family Lauraceae that have been severely affected by the laurel wilt disease, with high mortality recorded in the southeastern United States. Laurel wilt disease has infected yard and experimental avocado trees (Persea americana ) and poses an imminent threat to commercial avocados groves in Florida, California and Mexico.  The life cycle and development of X. glabratus were studied in the logs of avocado at 16, 18, 20, 24, 28, 32 and 36°C. Xyleborus glabratus successfully completed its life cycle at 24, 28, 32 °C. There were no developmental stages encountered at 16, 18, 36°C.  The optimal temperature for life cycle of the beetle was around 28 °C. Development of egg and pupal stages of X. glabratus were studied at 12, 16, 18, 20, 24, 28, 32 and 36°C. There was no development of egg and pupal stage observed at 12°C. The optimal temperature for development of X. glabratus eggs and pupal stages ranged between 24-28°C. Temperature-dependent development of the symbiotic fungus Raffaelea lauricola was studied at  20, 24, 28, 32, 36 °C. Optimal temperature for fungal development was observed between 24-28°C. Our results suggest that the temperature will play an important role in spread and successful establishment of beetle-fungal complex based on the latitudinal distribution of host.