Entomopathogenieity of Beauoeria bassiana and Metarhizium anisoplioe (Hyphomycetes) to the onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae)


ABSTRACT: The pathogenicity of 10 isolates of entomopathogenic fungi to the onion thrips, Thrips tabaci Lindeman, was evaluated in the laboratory. All fungal isolates tested were pathogenic to adult T. tabaci. Isolates of Beauveria bassiana (Bals.) Yuill. caused
mortality of 30 to 100% while isolates of Metarhizium anisopliae (Metsch.) Sorok. caused mortality of 70 to 100% 7 days after inoculation. LT50 values varied from 3.0 to 8.1 days and 2.5 to 5.3 days within B. bassiana and M. anisopliae isolates, respectively. LC50 values of the four most active isolates (B. bassiana ICIPE 83 and 85, and M. anisopliae ICIPE 69 and 74) ranged from 1.5 x 105 to 5.7 x 106 conidia ml” with M. anisopliae ICIPE 69 producing the lowest LC 50 value. All stages of T. tabaci were susceptible to infection by M. anisopliae ICIPE 69, although the larval and pupal stages were less susceptible than the adult stage. Mortality in all stages was dose-dependent, with the highest mortality occurring at 1 x 108; conidia ml’. The potential of M. anisopliae ICIPE 69 as a rnycoinsecticide for T. tabaci control on onion is discussed.

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