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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Publications at this Location » Publication #397773
Research Project: Biological Control of Invasive Pests in Agroecosystems and Wetland, Forest and Rangeland Ecosystems in the Far Western U.S.

Location: Invasive Species and Pollinator Health

Title: A comparison of candidate banker plants for management of pests in lettuce

Author
item Hogg, Brian
item NELSON, ERIK - Dominican University Of California
item DAANE, KENT - University Of California Berkeley

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2023
Publication Date: 4/12/2023
Citation: Hogg, B.N., Nelson, E.H., Daane, K.M. 2023. A comparison of candidate banker plants for management of pests in lettuce. Environmental Entomology. 52(3):379-390. https://doi.org/10.1093/ee/nvad029.
DOI: https://doi.org/10.1093/ee/nvad029

Interpretive Summary: Resources for natural enemies are often lacking in crop fields. Providing supplemental prey may allow natural enemies to persist in crop fields when food levels are low. In this study, we tested the potential of eight plants for providing supplemental prey to natural enemies in lettuce fields in California. None of the plants harbored high numbers of the main lettuce pest, the lettuce aphid. Barley showed the most promise and contained high numbers of non-pest aphids and provided reliable habitat for predatory fly larvae. However, high numbers of lettuce aphids were already present in lettuce fields in spring and early summer and may have dwarfed any benefits that non-pest aphids provided to natural enemies. Numbers of predatory fly larvae were also high in lettuce. Although barley showed promise as a source of supplemental aphids, it did not improve pest control in adjacent lettuce. Results suggest that plants containing supplemental prey improve pest control only when they provide more prey for natural enemies than the crop itself.

Technical Abstract: Agricultural systems are often lacking in resources for natural enemies. Providing alternative prey may allow natural enemies to persist through periods of low pest abundance, although this approach has been used only rarely in open field crops. In this study, we tested the potential of eight plants for providing alternative prey to natural enemies in lettuce fields in California. Results showed that the tested plants would not act as sources of the primary lettuce pest, the lettuce aphid Nasnovia ribis-nigri Mosley. Although results were somewhat inconsistent between years, barley contained high numbers of non-lettuce aphids and appeared to provide reliable habitat for hoverfly larvae. However, lettuce aphids were present on lettuce early in the season, and may have dwarfed any effects of non-lettuce aphids on natural enemy populations. Numbers of hoverfly larvae were also high in lettuce, but did not appear to track numbers of non-lettuce aphids on non-crop treatment plants. In contrast, numbers of lacewing larvae were highest on plants containing high numbers of non-lettuce aphids, and predatory hemipterans appeared to be associated with numbers of thrips on plants. Although barley showed promise as a source of alternative aphids, it did not appear to improve pest control in the adjacent crop. Results suggest that pest control benefits may develop only when the non-crop plant outperforms the crop as a source of alternative prey.