Toxicity of Some Entomopathogenic Fungi Combined with Boric Acid Againts Adults of American Cockroach Periplaneta americana (L.) (Blattodea: Blattidae)

Abstract

In this study, the pathogenicity of some entomopathogenic fungi on American cockroach Periplaneta americana (L.) adults and the effect of the most effective fungus isolate combined with boric acid on the virulence of the fungus were investigated in laboratory conditions. According to the results obtained from the experiments, the most effective isolate was found as Beauveria bassiana 5-4 and when it was used on insects, it caused 0%, 66.6% and 93.3% mortality at the dose of 0.1×109 conidia cm-2 at 72, 96 and 120 hours, respectively. This fungus also caused 0%, 20% and 20% mortality, respectively, at dose of 0.05×109 conidia cm-2 in the same time period. When boric acid was used on insects, it caused 6.6%, 40% and 66.6% mortality at dose of 1 mg cm-2 at 72, 96 and 120 hours, respectively. When 0.1×109 conidia cm-2 dose of B. bassiana 5-4 was used together with 1 mg cm-2 dose of boric acid, 33.3%, 60% and 93.3% mortality occurred at 72, 96 and 120 hours, respectively. When 0.05×109 conidia cm-2 dose of B. bassiana 5-4 was used together with 1 mg cm-2 dose of boric acid, 33.3%, 60% and 86.6% mortality occurred at 72, 96 and 120 hours, respectively. The results showed that the combined use of boric acid and B. bassiana 5-4 increased the virulence of the fungus at short exposure times (72 and 96 hours), but did not significantly affect the virulence of the fungus at long exposure times (120 hours and above).