Efficacy of Anystis baccarum against Foxglove Aphids, Aulacorthum solani, in Laboratory and Small-Scale Greenhouse Trials.

Abstract

Simple SummaryThe foxglove aphid (FGA), Aulacorthum solani (Keltenbach), feeds on many important greenhouse crops in Canada. Currently, biological control of this pest is difficult as existing biocontrol agents are only moderately effective. Access to a generalist predator would strengthen biocontrol programs for this and other similarly challenging pests. Anystis baccarum (L.) is a globally distributed generalist predatory mite. We assessed the predatory efficacy of A. baccarum against FGA in a series of laboratory and small-scale greenhouse trials. The laboratory trials showed that A. baccarum readily consumed all FGA life stages and was particularly effective against first instars. In a greenhouse trial on sweet peppers, working together with Aphidius ervi Haliday, an aphid-specific parasitoid wasp, A. baccarum successfully eradicated the aphids and higher fruit yields were obtained compared to plants protected by the parasitoids only. Pepper plants also became naturally infested with western flower thrips during the trial, which caused feeding damage to the fruits. The fruits were likely to have less thrips’ feeding damage on plants carrying A. baccarum as the predator also fed on these pests. The results demonstrate that A. baccarum could be a useful addition to greenhouse IPM programs for hard-to-control pests like FGA, especially when they occur together with other pest species.A generalist predatory mite, Anystis baccarum (L.), has been identified as a key predator of small, soft-bodied pest species in various agroecosystems around the world. The foxglove aphid Aulacorthum solani (Keltenbach) is a new problematic pest in Canadian greenhouses. Laboratory colonies of A. baccarum were established and its predatory efficacy against A. solani was assessed. In laboratory trials, A. baccarum ate approximately one adult aphid or seven first instar aphids in 24 h. In a greenhouse bench trial on sweet peppers with the free-flying aphid parasitoid, Aphidius ervi Haliday, the population dynamics of A. solani in the presence or absence of A. baccarum was evaluated. Although the parasitoid alone successfully eradicated A. solani, when A. baccarum were present on the plants, the aphid population was eradicated more rapidly. Fruit yield was also 15% higher from plants where A. baccarum was released than the control (without A. baccarum). Furthermore, plants were naturally infested by Frankliniella occidentalis (Pergande) during the trial, which caused visible feeding damage to the fruits. Anystis baccarum also predates on thrips and thrips’ feeding damage to the fruits was reduced on plants where A. baccarum was released. Anystis baccarum was able to establish in sweet peppers and was determined to be complementary to the current practice of using A. ervi for the biological control of A. solani.