Safety of fungal biocontrol agent Gliocladium catenulatum to its vector the Carniolan honey bee

Summary

Grey mold (Botrytis cinerea) is one of the most important strawberry diseases. It can be suppressed by fungicides or by biocontrol agents, which can be spread by bees. We examined the impact of the biocontrol agent Prestop Mix (PM) with Gliocladium catenulatum spores on bees’ response to food stimuli, mortality, and behavior inside and outside of a dispenser mounted on a hive. We tested effects on response to food stimuli by classical conditioning of the proboscis extension reflex. The results did not confirm any effect. We monitored the impact on mortality in cages in an incubator for four days. Compared with the control group, mortality was two times higher for the bees that were exposed to PM only on the first day and four times higher for bees that were exposed to PM every day. We monitored the bees’ behavior inside and outside the dispenser with a camera. PM drastically changed the bees’ behavior. Changes were most obvious in the first hour, and then subsided. We suggest some improvements to the dispenser and also a change in the preparation of PM in order to decrease the negative effect on honey bees and also increase the efficiency with which it is spread.