Already a big problem in its own right, the Brown Marmorated Stink Bug has been joined in the US by its heat loving cousin, the Bagrada Bug, Bagrada hilaris or Bagrada cruciferarum, Family Pentatomidae. And yes, it’s a stink bug. This bad-news-bug from Africa is causing significant damage to crops from home gardens to commercial growing operations in the desert Southwest. Losses from infested conventionally grown cole crops are at 20 to 25 percent. Organic farmers are hardest hit at 45 to 50 percent. A publication by John C. Palumbo, at the website of the University of Arizona, Yuma Agricultural Center indicates that the pest feeds on and damages seedlings, new foliage and meristems (growth points) of cruciferous plants causing severe damage and deformation that makes the crops unusable as fresh produce. The list includes crops such as cabbage, kale, cauliflower, broccoli, mustard, turnip, arugula and rutabaga. It is also known to damage radish, watermelon, papaya, beets, potato, maize, sorghum, cotton, capers, pearl millet and some legumes. In non-crop areas it is sustained by feeding on weeds such as field bindweed, purple nutsedge, lamsquarter, black mustard, perennial sowthistle and perhaps sheperdspurse.
According to a report in the Western Farm Press, dated 2010-03-04, by Jian Bi, Entomology Farm Advisor, Monterey County, the Bagrada Bug was first discovered in Pasadena in 2008. Lacking any natural enemies in the United States it has rapidly expanded from its point of introduction into seven Southern California counties and Yuma County, Arizona. The Bagrada Bug is easily confused with the similarly shaped and colored, but larger stink bug relative, the Harlequin Bug, Murgantia histrionica. Gevork Arakelian, Senior Biologist, Los Angeles County Agricultural Commissioner, Weights & Measures Department says in a report at the UC Riverside Center for Invasive Species Research website, “Adult Bagrada bugs are 5-7 mm long, and have black, shield-shaped bodies with distinctive white and orange markings. Adult females are larger than males.” The adult of the Harlequin Bug, established in the US since its initial identification in Texas circa 1864, is 8-11 mm in length, according to the online site, “BugGuide.” Each female is capable of laying up to 100 eggs in 2-3 weeks, which she attaches to the undersides of host plant leaves or places in the soil. The eggs are barrel shaped and initially white, changing to orange as they age. The bug has five nymphal stages, called instars, between egg and adulthood. Newly hatched nymphs are orange and sometimes confused with ladybug adults. Their color becomes darker with each molt until they develop the characteristic black with white and orange markings. The wings develop gradually, with the insects becoming capable of flight in the adult stage. Photos of various instars can be seen at the Infonet-Biovision.org website.
Experts are hard at work seeking practical control methods including parasitic organisms and other natural predators. For now organic growers are emphasizing methods such as planting during cooler seasons, physical removal of the insects and treatment with materials such as diatomaceous earth, insecticidal soaps, neem and other insecticidal oils. In the short term those favoring conventional methods mention materials like carbamates, imidocloprid, various pyrethroids and other conventional insecticides as possibilities. It’s logical to assume that information will be made available to the public as research and governmental regulations catch up with this infestation. Gardeners and commercial growers should only use organic methods or conventional materials currently registered for use against these bugs in their geographic locations and use them strictly according to label directions. One thing we can be relatively sure of is that Bagrada hilaris represents another in the long list of serious threats to US crops that must be addressed without delay.
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