Translocation and survival of trunk injected Beauveria bassiana (Hypocreales: Cordycipitaceae) in healthy date palm trees

Abstract

Objective: The date palm, Phoenix dactylifera L., is an ancient and valuable tree that provides food and other products. The date palm trees are attacked by several pests, including the red palm weevil, which is devastating to date palm plantations. Knowledge of the functionality of entomopathogenic fungi, including Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae) species, in the tree trunk is critical for controlling date palm weevil and other pests. The goal of this study was to assess the movement of the entomopathogenic fungus, B. bassiana, within the date palm tree. Methods: Beauveria bassiana (BbSA-4) mixed with food colors was trunk-injected using a balloon injector into healthy date palm plants. Trunks were cut into one-meter logs 2, 20, and 86 days post-injection. Each log was further dissected into four quarters to examine the present of the fungus. The appearance of food colors and the detection of fungal spores at different heights from the point of injection revealed the translocation of B. bassiana within the trunk. The samples were taken from several locations where food color could be visible, and the distance traveled by the fungal spores was measured. Results: The injected palm tissue samples were cultured on PDA media in the laboratory, and the present of fungal spores was confirmed. B. bassiana (BbSA-4) was found to be surviving in all treated date palm trees. The survival rate of isolate BbSA-4 averaged 70.5%, 34.9%, and 13.9% from dissected trunks examined at 2, 20, and 86 days, respectively, after injection. Isolate BbSA-4 was more apparent in the trunk after spiral injected than bottom injection. The findings revealed that using an entomopathogenic fungus as an endophytic to supplement IPM programs could be beneficial.

Keywords

• Entomopathogenic fungus
• Germination
• Trunk treatment
• Trunk injection