Using honeybees to improve pollination of strawberries and to deliver biological fungicide for protection from grey mould (Botrytis cinerea)

Summary

Organic berry production suffers heavily from lack of effective disease control and from inadequate insect pollination. BICOPOLL is a European study on protection of strawberries from their most important disease, the grey mould (Botrytis cinerea), using spores of fungus Gliocladium catenulatum in Prestop Mix (PM). G. catenulatum, which acts as an antagonist of grey mould, was delivered to strawberry flowers using honeybees. Bees gathered PM in a dispenser placed at the exit of the hive and delivered it to the flowers. A colony of Apis mellifera carnica honeybees was placed next to a 0.5 ha strawberry field in NW Slovenia during May and June of 2013 and 2014. Foraging activity and yield were monitored in eight experimental plots (4 treated and 4 controls) at different distances from the bee colony. Number of honeybees on strawberry flowers was counted four times a day. Bees visited the strawberry flowers despite alternative food sources close to the field. The visits were more frequent in warm weather and in the afternoons. Each year at the end of the flowering season, the healthy and the mouldy berries were collected from each plot and weighed. In 2013, the use of PM resulted in a 50% increase of the ratio of healthy berries over the mouldy ones. In 2014, no statistically significant differences between treated and untreated plots were found, presumably due to lower foraging activity of bees in cold and rainy weather in the flowering period. The results showed that, in favourable weather conditions, entomovectoring is an effective method for delivering biocontrol agents to flowers.