Application of indigenous honeybees in dispersing Trichoderma harzianum spores for control of the strawberry grey mould

摘要

The prevention and control of strawberry grey mould are typically done via the traditional application of fungicides or spraying of fungal spores. However, the exploitation of honeybees for dissemination of biocontrol agents during pollination is more environment-friendly. To evaluate the feasibility of this novel strategy in dispersing fungal spores on strawberry plants, we first investigated the toxicological effect of Trichoderma harzianum spores on the eastern honeybee, Apis cerana cerana. Then, we evaluated the dissemination efficiency of spore powder, the optimal type and dilution ratio of dispersants, and the efficacy of fungal control in a strawberry greenhouse experiment. The results revealed that no acute oral toxicity/ low contact toxicity of T. harzianum on A. cerana cerana. The number of spores carried by bees reached maximum after a three-minute contact between the bees and T. harzianum spore powder, and the number of spores released by the bees was maximum after five minutes. We demonstrated that the application of dispersants, such as wheat flour, could mitigate the decline in the spore carrying capacity of bees caused by high humidity levels. Greenhouse experiments showed that bees could successfully deliver the spores to strawberry petals. The average number of spores deposited on strawberry flowers was 1.31x10 (6) CFU/flower, which was effective in controlling the grey mould in the field. Our study provides novel insights into the application of indigenous bee species to disseminate T. harzianum spore powder to control and prevent the strawberry grey mold, under both laboratory and greenhouse conditions.