Phyllotreta cruciferae and P. striolata, the crucifer and striped flea beetle, respectively, are significant pests of crops in the plant family Brassicaceae. Adult foliar feeding causes a characteristic “shotgun” pattern, reducing marketability of crops with edible foliage. These multivoltine species overwhelm cropping systems when overlapping generations result in a constant presence of beetles through the growing season. In Indiana high tunnels, the growing season is extended, and multiple, consecutive Brassica plantings are common. Brassica crops are an important part of local food systems, with over 95% of cruciferous vegetables grown in the state sold direct-to-consumer. In fresh market sales, tolerances for pest damage are low, and thus, flea beetle damage reduces marketability. The highly mobile flea beetles are largely controlled using chemical insecticides, with few options for growers who use low-input practices. Several species of entomopathogenic nematodes (EPN) have successfully infected soil-dwelling flea beetle larvae, but these biocontrol agents do not decrease damage from the overwintering adults. We propose that effective flea beetle control must interrupt host-seeking of the overwintering generation as well as decrease the impact of their progeny. This study evaluates combining the use of a mustard (Brassica juncea) trap crop and application of commercial EPN products to intercept overwintering adults, encourage oviposition outside of a collard green (B. oleracea) cash crop grown in high tunnels, and induce larval mortality through biological control, preventing feeding damage to crop foliage.
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