Bagrada Bug Update

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The Pest and the Damage Done
The invasive stinkbug known as the Bagrada bug continues to hopscotch its way through California. First found in Los Angeles County in 2008, it is now found throughout the state as far north as Yolo County. The pest has caused damage to many organic crops this summer and fall, primarily to mustard family crops including kale, arugula, broccoli, cabbage, collards, and other mustard greens. Bagrada bug also has caused damage to peppers, melons, tomatoes, corn, snap beans, and sunflowers.

Female (top), mating pair (middle), and a mature nymph (bottom) of Bagrada bug on a dime. Photo by Surendra Dara

Management Suggestions
Bagrada bug is strongly attracted to sweet alyssum, a plant commonly grown on field borders to attract beneficial insects, and weeds like wild mustards, shepherd’s purse, and pepperweed. Because of this, one promising management strategy is to plant a field border of sweet alyssum or another trap crop to lure the Bagrada bugs into it, then vacuum the Bagrada bugs out of the sweet alyssum. This strategy will also inevitably destroy a portion of the beneficial insect community but, because many beneficial insects are more mobile than the Bagrada bugs, they may be able to escape the vacuum more easily.

Bagrada bugs seem to be most active when the weather is hot (temperature above 75 degrees Fahrenheit) and to slow down later in the season. Some growers in southern California have resorted to delaying brassica production until later in fall when the weather is cooler. Growers have noted that the bugs prefer young, tender leaves. Planting robust transplants (at the 4-leaf stage) may reduce attractiveness to the bugs. Are any pesticides effective against Bagrada? Bagrada bug is difficult to control using typical organically-approved pesticides because of its tough exoskeleton. To date, no pesticides have provided reliable control of the pest. Surendra Dara, Strawberry and Vegetable Crops Advisor and Affiliated Integrated Pest Management (IPM) Advisor with UC Cooperative Extension, has conducted laboratory trials of non-chemical pesticides including entomopathogenic fungi, bacterial metabolites, pyrethrins, insecticidal soap, and essential oils. He found that the insect pathogenic fungal formulation Mycotrol O caused mortality in Bagrada bug adults. Dara’s work on organic management options is continuing this fall.

At the same time, Shimat Joseph, IPM Advisor with Cooperative Extension Monterey County, is a member of a team that has received a Specialty Crop Block Grant from California Department of Food and Agriculture to study management of Bagrada bugs in the Salinas Valley. Joseph is conducting two trials of organic products for efficacy in controlling the Bagrada bugs and has studied Bagrada bugs trapping strategies.

In the interim, Joseph recommends applying pyganic and soap at least twice per week.

Further Information
The most recent UC Cooperative Extension information on Bagrada bugs are on the Santa Barbara and Monterey county websites. UC’s IPM program issued a pest alert on Bagrada bugs last year. An Entomology Seminar offered by UC Cooperative Extension Monterey County will feature a talk on the biology and management of Bagrada bugs. The seminar will be held December 2, 2014, at the UC Cooperative Extension Auditorium in Salinas, California. More information posted has been provided by the Monterey County UCCE.