Compatibility of Amblyseius swirskii with Beauveria bassiana: two potentially complimentary biocontrol agents

The two biocontrol agents Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) and Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae) have the potential to complement one another as part of an integrated pest management programme. While both can suppress whitefly and thrips infestations in protected crops, A. swirskii is primarily used preventatively whereas B. bassiana can be used as a curative treatment at higher pest levels. With this concomitant use in mind, the research presented here aimed to identify potential negative effects of the commercial B. bassiana strain GHA on A. swirskii in a laboratory study. Adult A. swirskii were found to be susceptible to B. bassiana infection with slight to moderate virulence (20.74 ± 3.89 to 48.33 % ± 3.07) depending on the type of exposure and with a reduction in fecundity over time. There was however no negative effect on juvenile survival neither on dry residue nor on the offspring of infected mites. Thus, these two biocontrol agents do have the potential to be complementary. Further trials in the field are still required before a final conclusion can be reached