Susceptibility of Myzus persicae, Brevicoryne brassicae and Nasonovia ribisnigri to fungal biopesticides in laboratory and field experiments

The aim of this study was to evaluate the potential of entomopathogenic fungi (EPF) for the control of aphid pests of field vegetable crops. Four biopesticides based on the EPF Beauveria bassiana (Botanigard ES and Naturalis L), Cordyceps fumosorosea s.l. (Preferal WG), and Akanthomyces dipterigenus (Vertalec) were evaluated in a laboratory bioassay against peach-potato aphid Myzus persicae, cabbage aphid Brevicoryne brassicae, and currant-lettuce aphid Nasonovia ribisnigri. There was significant variation in the spore dose provided by the products, with Botanigard ES producing the highest dose (639 viable spores per mm2). Botanigard ES also caused more mortality than the other products. Combining Vertalec with the vegetable oil-based adjuvant Addit had an additive effect on the mortality of B. brassicae. All fungal products reduced the number of progeny produced by M. persicae but there was no effect with B. brassicae or N. ribisnigri. When aphid nymphs were treated with Botanigard ES and Preferal WG, both products reduced population development, with up to 86% reduction occurring for Botanigard ES against M. persicae. In a field experiment, Botanigard ES sprayed twice, at seven-day intervals, against B. brassicae on cabbage plants, reduced aphid numbers by 73%. In a second field experiment with B. brassicae, M. persicae, and N. ribisnigri, Botanigard ES reduced populations of B. brassicae and N. ribisnigri but there was no significant effect on M. persicae