The entomopathogenic fungus Beauveria bassiana and the predatory mite Neoseiulus barkeri are both potential biocontrol agents for their shared host/prey Frankliniella occidentalis. The combination of the two agents may enhance biological control of F. occidentalis if the fungus does not negatively affect N. barkeri. However, the potential benefits and hazards of using fungus and predators simultaneously have not yet been widely evaluated. Therefore, a better understanding of the interactions between fungus and predators will improve their integration into pest management practices.

Recently, researchers at State Key Laboratory of Plant Diseases and Insect Pests, Institute of Plant Protection of CAAS have published a research paper on Scientific Reports about risk evaluation of indirect effects of B. bassiana strain SZ-26 on predatory mite N. barkeri. The study showed that B. bassiana has indirect negative effects on N. barkeri population dynamics via influencing their prey F. occidentalis larvae, and the biological parameters of the predators, including the mean generation time (T), net reproductive rate (R0), finite rate of increase (λ), intrinsic rate of natural increase (rm) and predation were affected. The findings indicate that there is a risk in combining B. bassiana with N. barkeri simultaneously for the biocontrol of F. occidentalis. The probable mechanism for the negative effects is discussed.

More details are available on the bellow links:
http://www.nature.com/srep/2015/150708/srep12033/full/srep12033.html