Characteristics of Beauveria bassiana isolates from Lygus lineolaris populations of Mississippi.

摘要

Beauveria bassiana (Balsamo) may provide a much-needed option for control of Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae). Fungal isolates from L. lineolaris populations native to cotton-growing regions may be better adapted for controlling these populations. Nineteen B. bassiana isolates from L. lineolaris in Mississippi were evaluated for characteristics relevant to production and efficacy of a mycoinsecticide for Lygus control. Characteristics included pathogenicity to L. lineolaris adults, in vitro conidial production, tolerance to artificial sunlight, and germination at 35 degrees C. Comparisons were made among these 19 isolates, a B. bassiana isolate from L. lineolaris in Arkansas (ARSEF 3,769), and a commercial B. bassiana strain (GHA). Eleven of the isolates from L. lineolaris were significantly more pathogenic than B. bassiana (GHA) based on LC50 values, with several having LC50 values more than 10 times lower than B. bassiana (GHA). The higher pathogenicity of these isolates was also reflected in lower LT50 values and higher sporulation of cadavers, particularly at intermediate conidial concentrations. Isolates from L. lineolaris were generally prolific conidia producers, producing conidial concentrations on barley agar similar to or greater than B. bassiana (GHA). All isolates were highly susceptible to the negative effects of artificial sunlight. One isolate from L. lineolaris in Mississippi germinated at 35 degrees C and all others exhibited little or no germination at this temperature. These laboratory studies indicate that isolates from L. lineolaris may improve mycoinsectide efficacy through higher pathogenicity, particularly if the negative effects of solar radiation and high temperatures could be mitigated by formulation or application strategies..