Lethal and Sub-Lethal Effects of Beauveria bassiana (Cordycipitaceae) Strain NI8 on Chrysoperla rufilabris (Neuroptera: Chrysopidae)
2017
Portilla, Maribel | Snodgrass, Gordon | Luttrell, Randall
A Mississippi Delta native strain (NI8 ARSEF8889) of Beauveria bassiana (Balsamo) Vuillemin (Sordariomycetes: Hypocrales), isolated from Lygus lineolaris (Palisot de Beauvois), was bioassayed on green lacewings, Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae) at four spray concentrations (7.02 x 104, 105, 106 and 107 spores/ mL) to evaluate effects on the insect predator’s reproductive rates and adult life expectancy. The application method simulated atomized spray and concentrations tested were similar to those used to measure impacts of the fungus on L. lineolaris. Significant effects of B. bassiana on adults of C. rufilabris were found and the severity of impact depended on the concentrations tested. Beauveria bassiana impacted all demographic measurements of C. rufilabris reproduction and survival. Intrinsic and finite rate of increase and gross and net reproductive rates of adults treated with the highest concentrations tested were significantly decreased while doubling time increased for adults treated with the lowest test concentrations. Based on these observations, C. rufilabris will be affected by sprays of B. bassiana targeted at L. lineolaris if they are present at the time and location of treatment. The measured LD50 of 2.11 viable spores per mm2, compares to a LD50 of 2.71 spores per mm2 for L. lineolaris (Portilla, 2014). Higher concentrations were needed for sporulation (LS50 of 13.60 viable spores per mm2) of the entomopathogenic fungus on C. rufilabris (13.60 viable spores per mm2) than concentrations required for mortality (LC50).
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