Another Invasive Pest - Bagrada Bug
Most growers in Maryland and Delaware have had experiences with the brown marmorated stink bug since they have been spending the winter visiting many homes in the region. The stink bugs, not the growers. Just when you got cozy with this intruder, we now have another true bug invasion of the United States. The brown marmorated stink bug spread from Pennsylvania to the west, north, and south. This new bug showed up in the west and is spreading east. It’s called bagrada bug, Bagrada hilairis (Hemiptera: Pentatokmidae).
Fortunately it is does not feed on the wide range of plants that brown marmorated stink bugs does. Bagrada bugs feed mainly on plants in the Cruciferae, but even that is changing as they spread in the United States. An email from Baldo Villega reported “I am with the California Department of Food and Agriculture. At this time the bagrada bug is restricted to southern California. I am in Sacramento which is considered northern California and I have not seen any bugs yet. All the homeowner emails I received last year were from San Diego County. These homeowners are finding them mainly on their ornamental annuals such as sweet alyssum and in their vegetable gardens.”
Bagrada hilaris showed up in California in June 2008. Since then, they have become more widespread in southern California and have expanded their range into Arizona, where they are reported to be significant pests. The bug has been intercepted in Florida but was destroyed before it was established. It is probably just a matter of time until we see it on the East Coast. Vegetable growers and cut flower growers (those who grow ornamental cabbage for cut stems) need to stay alert and watch for this bug.
Bagrada bugs look very similar to the common harlequin bug, Murgantia histrionic (Hahn) but are considerably smaller. The two species have similar biology. Look for small, dark insects about 3/16 of an inch long, with a characteristic pattern of longitudinal lines. Nymphs are mainly dark with pale to dark red markings. Harlequin bugs, which are widespread in the U.S., have a different pattern with perpendicular orange stripes. Both species can be found in large numbers on cruciferous plants.
Several generations can be completed per year, depending on temperature. Eggs are laid on seed pods, foliage, or soil surrounding young plants. The egg stage lasts 3 to 6 days. There are five nymphal instars. First to fourth instar immatures are orange after molting, but darken with age. The fifth instar resembles the adult. The entire life cycle in the laboratory was completed in 38-65 days. The average fecundity per female is 95 (range 36-173) eggs.
This species is a major pest of cruciferous crops in the Old World and is reported to be a major pest in California and Arizona. In Arizona, they attacked both direct-seeded and transplanted broccoflower, broccoli, cabbage, cauliflower, Chinese cabbage, kale, collards (all Brassica oleracea L.), radish, rutabaga (Brassica napus L. var. napobrassica (L.) Rchb.), arugula (Eruca vesicaria (L.)), turnip (Brassica napus L.) and mustard (Brassica juncea (L.) Czern.) (Palumbo and Natwick 2010). Bagrada bugs are particularly damaging.
You can find photos of the bagrada bug on the web. If you find an unusual bug feeding on your ornamental plants this year get a sample to an extension office or your local Department of Agriculture.
Stanton Gill is an extension specialist (professor-ranked principal agent) in IPM and entomology with the University of Maryland Extension, based at the Central Maryland Research and Education Center in Ellicott City. He is also a professor in the Landscape Technology Program at the Germantown Campus of Montgomery College. Contact him at [email protected]