Untangling the effects of predator releases and transient natural enemies on pest populations in strawberry high tunnels in Mississippi

Authors: Riddick, Eric

Submitted to: Entomological Society of America, Southwestern and Southeastern Branch
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Evaluating the effectiveness of augmentative releases of natural enemies is crucial to providing convincing evidence that pests can be managed in lieu of pesticides. Separating the contribution of released natural enemies from those that invade high tunnel greenhouses in search of prey/hosts, is challenging. We tested the effects of ladybird (Coleomegilla maculata) releases on aphid (Aphis ruborum) density on potted strawberry plants in replicate high tunnels. We also evaluated the effect of releasing predatory mites (Phytoseiulus persimilis) to reduce two-spotted spider mite (Tetranychus urticae). The number and fresh weight of strawberries produced in these high tunnels were also determined throughout the fruiting season, February - June 2017. The results indicate that aphid and spider mite densities declined in several weeks, post-release of predators. Aphid mummies (i.e., immature parasitic wasps developing inside the bodies of aphids), syrphid flies, and other ladybird species (e.g., Harmonia axyridis) were also in the high tunnels. This study suggests that an early season release of mass-reared C. maculata adults or larvae could reduce an early season buildup of aphids. Later in the season, naturally-occurring ladybird beetles, aphid parasitoids, and syrphid larvae could limit pest (aphid) population growth in high tunnels. Strawberry production was greatest in one of the high tunnels in which C. maculata were released, but not the other one. Generally, strawberry production was unaffected by predator releases.