Insights into the complexities of fungus-insect-plant interaction: The laurel wilt disease

Abstract

Laurel wilt disease, caused by the fungus Harringtonia lauricola and transmitted by the ambrosia beetle Xyleborus glabratus, poses a significant ecological and economic threat to various species of the Lauraceae family, particularly avocado. The disease is characterized by the formation of tyloses blocking xylem vessels, hindering water conductance, and decreasing leaf gas exchange. The relationship between the fungus and the beetle is complex and not fully understood, which can be described, in general, as ambrosial symbiosis depending on the habitat. The secretome of the pathogen includes hydrolytic enzymes that aid in colonization and resistance of host defence. This paper reviews the current understanding of the causes, impacts, and management strategies for laurel wilt disease. Also, it provides an overview of the complex relationship between the fungal pathogen and its beetle vector and explores the various virulence factors and secretome of H. lauricola that contribute to the aggressive nature of the disease. Moreover, this review states the ecological and economic impacts of laurel wilt, particularly on ecologically and economically valuable plants such as avocado. Current management strategies for controlling the disease, including the use of insecticides, fungicides, and biological control methods, are reviewed. Finally, we highlight some critical key points in ambrosia symbiosis biology that are of importance for disease control.