Field persistence of Metarhizium spp. strains applied as biocontrol agents against ticks (Ixodes ricinus)

Abstract: In two semi-field trials the persistence of three Metarhizium strains (BIPESCO 5,ARSEF 3297, ARSEF 4556) after foliar spray application was monitored and bioassays withTenebrio molitor larvae were made to preclude a negative effect on germination and vitality ofconidia by using the adhesive agent Neo-wett™ and the antifoaming agent AntischiumaSchaumstop™. Three different outdoor conditions (i.e. unprotected, rainfall protected, rainfallprotected and fully covered) were tested and all strains showed an adequate persistence after 25days (20-50%). BIPESCO 5 conidia were re-isolated from foliage even after heavy rain showersin open sites after 44 days. Conidia showed high virulence in bioassay with and without Neowett™ and Antischiuma Schaumstop™: 90% of all larvae were killed after 5 to 20 days. Nonegative effects of the adhesive- and antifoaming agent on the germination ability and vitality ofMetarhizium conidia were observed.