| To obtain the high virulent Metarhizium strains toward the pest Brontispa longissima, The dead B. longissima were collected from the areas where coconuts were severely damaged by B. longissima. Sixteen strains of Metarhizium species were further isolated. The virulence was measured with adults and 4th-instar larvae of B. longissima, and the high virulent strains CM1601 and HK1304 were screened. The LT50 values of CM1601 were 4.1 and 3.9 d to adults and 4thinstar larvae of B. longissima, and those of HK1304 were 4.4 and 4.2 d, respectively. Through the further virulence test, we found the virulence of CM1601 and HK1304 reached peak when concentration of conidia were 1.0×108 conidia/mL and 2.5×108 conidia/mL, respectively. The strain CM1601 and HK1304 were identified as M. anisopliae and M. anisopliae var. acridum by the analysis of ITS sequences and phylogenetic tree. Thus, both strains are highly potential for use in microbial control of B. longissima. |
