Managed bees as pollinators and vectors of bio control agent against grey mold disease in strawberry plantations

Abstract

Pollination by bees and other animals significantly increase both crop yields and quality. Bees also support the transfer of bio-control agents for suppression of crop pests and diseases through bio-vectoring technology that has not been applied in Africa. Two farms were set up to test the ability of managed bees to disseminate Trichoderma harzianum to control Botrytis cinerea, on strawberries. At on-station farm, three treatments (bee-vectoring inoculum, spraying and control) with 4 replicates each were set up; while on-farm, normal farmer practices were employed. A nuclear beehive fitted with a two-way dispenser was loaded with two grams of T. harzianum inoculum. Fifteen bees and flowers from each treatment were picked and cultured in the laboratory. Fruits and flowers infected with B. cinerea were recorded, while healthy fruits were counted, weighed and equatorial and polar diameter determined. Each bee carried 22.4±4.9×102 colony -forming units of T. harzianum. Flowers from the sprayed treatment had significantly higher Colony-Forming Unit’s F (3,140), (P˂0.05) than the bee-vectored treatment. Grey mold disease levels on fruits were significantly lower (P˃0.05) in sprayed, bee- vectored and control treatment than in farmer’s practice treatment. Fruits from spray treatment weighed significantly higher than those from control treatment F (3,2122), (P˂ 0.05). The number of seeds, equatorial and polar diameter per berry were significantly higher (F=3, 2122, P˂0.05) in farmer’s practice treatment. Managed bees proved effective in vectoring T. harzianum but, sufficient Colony-Forming units had to be delivered for effective control of the disease. Key words: Trichoderma harzianum, grey mold, strawberry, biocontrol agent, managed bees, bio-vectoring technology.