Resumen
- Metarhizium anisopliae (Hypocreales) is considered a virulent pathogen of the weevil Rhynchophorus palmarum; in addition to vectoring the red ring nematode (causal agent of the red ring disease), this weevil is considered the main primary pest of coconut and affects several other palm species in Latin America by direct larval feeding on stems, crown and petiols. Some entomopathogenic fungi have the ability to colonize endophytically a wide range of plants, offering protection against pests and diseases. The purpose of this study was to assess the virulence of M. anisopliae commercial strains Metarhiplant, Metatropico-9236 as well as newly isolated strains. For isolation of natural strains of M. anisopliae, adults of R. palmarum were collected from the main coconut growing area at the Colombian Pacific coast. A total of 150 adult weevils were captured and surface disinfected. Insects were placed in individual humid chambers and maintained at 25 ± 3 °C for 20 days. A single strain of M. anisopliae was obtained and labeled as JGVM1. Isolates used in this study showed significant differences in weevil mortality. The greatest mortality in the shortest time was achieved with strain JGVM1, reaching 100% mortality 17 days after inoculation. The commercial strains Metarhiplant and Metatropico-9236, presented 80 and 85% of mortality respectively at 17 days, and were significantly different from strain JGVM1 but did not show significant differences among each other. Lethality times LT50 and LT80 of strain JGVM1 (LT50 =11.3 days; LT80 =16.2 days) were lower than those observed for strains Metatropico 9236 (LT50 =14.1 days; LT80 =20.3 days) and Metarhiplant (LT50 =13.7 days; LT80 =19.6 days). The most virulent strain was used in experiments aimed to establish M. anisopliae as an endophyte within coconut seedlings as a form of biocontrol against the American palm weevil and the Red Ring Disease. Results will be discussed more extensively in the poster.