Abstract:The mirids are causing increasing damage in Chinese cotton production, and chemical control is almost the exclusive management option for these pests at present. In order to develop microbial control measure, the pathogenicity of seven strains of Beauveria spp. to three dominant mirid species, Apolygus lucorum, Adelphocoris suturalis and Adelphocoris lineolatus was assessed in the laboratory. The results showed that the pathogenicity of each strain varied greatly with mirid species. The strain C-1 had the greater pathogenicity against A.lucorum than A.suturalis and A.lineolatus, whereas the strains 07-2-3, 07-10-10, 07-10-11, 07-10-12 and 07-10-14 were highly effective against A.suturalis and A.lineolatus than A.lucorum. Among all the tested strains, C-1 had the greatest pathogenicity against the 2nd instar nymphs of A.lucorum with the LC50 value of 5.34×106 conidia/mL. Additionally, the pathogenicity gradually lowered with the increasing age of A.lucorum nymphs. At a concentration of 1×107 conidia/mL, the LT50 values of the strain C-1 against the 2nd, 3rd and 4th instar nymphs were 7.11, 8.37 and 12.44 d, respectively, and those were 3.14, 3.87 and 4.95 d at 1×108 conidia/mL. The Beauveria spp. has the potential of being used in microbial control of cotton mirids in China.