Co-vectoring of Beauveria bassiana and Clonostachys rosea by bumble bees (Bombus impatiens) for control of insect pests and suppression of grey mould in greenhouse tomato and sweet pepper

Greenhouse cage trials were conducted to assess the effectiveness of bumble bee pollinators for the co-vectoring of two fungi (Beauveria bassiana [Balsamo] Vuillemin [BotaniGard 22WP® formulation] and Clonostachys rosea Lnk: Fr. [Endofine®]), in greenhouse tomato and sweet pepper for control of insect pests (greenhouse whitefly, Trialeurodes vaporariorum Westwood; and tarnished plant bug, Lygus lineolaris [Palisot de Beauvois]), and grey mould (Botrytis cinerea Pers: Fr.). Three treatments were evaluated: 6.24 × 1010 conidia of B. bassiana + 1.38 × 107 conidia of C. rosea/g of inoculum vectored by bees (active inoculum); heat-inactivated inoculum vectored by bees; and a control with no inoculum and no bees. In each crop, the treatments were arranged in a completely randomized block design with four replications. When applied in the tomato crop, the active inoculum killed 49% of the T. vaporariorum and suppressed grey mould by 57% and 46%, respectively, on the flowers and leaves. In sweet pepper, mortality of L. lineolaris was 73% and grey mould was suppressed by 59% and 47%, respectively, on the flowers and leaves in the active inoculum treatment. The incidence of grey mould in sweet pepper and tomatoes treated with the heat-inactivated inoculum or no inoculum (control) was approximately 80% on the flowers and leaves. Thus, the combined inoculum of B. bassiana and C. rosea can potentially control T. vaporariorum and L. lineolaris, and suppress grey mould in greenhouse tomatoes and sweet peppers, when vectored simultaneously by bumble bees. Commercial greenhouse trials need to be conducted next to determine control efficacy under large scale production conditions.