The Bagrada Stinkbug
With an economic recession there may be many unwanted effects, and one of these could be that exotic insects have an easier time finding their way into North America. With reduced budgets some federal agencies have cut back on their personnel and their services, and one of the agencies impacted has been the Department of Agriculture. With less money available there has been a reduction in the inspection of products coming into the U.S. from other regions of the world, and damaging insects that are stowed away in produce, wood products, or ornamental plants may have less chance of being discovered and contained before they make their way into our environment.
One of the most recent imports is a colorful insect called the Bagrada Bug – Bagrada hilaris. This is a “stinkbug” in the family Pentatomidae, and until its discovery in Los Angeles County in 2008 it was known only from Africa, southern Europe, and the Indian region of Asia. In those native countries it is also known to be a severe pest of “cole” crops and related mustard crops, such as cauliflower, broccoli, kohlrabi, cabbage, and radish. For those who are not fans of these vegetables, it is important to know that this large stinkbug also has been found feeding on lettuce, melons, potato, cotton, and some kinds of beans or peas. They often feed most readily on fresh, young plants or new leaves, causing a distortion and wilting that destroys the plants or affects their marketability.
The Bagrada Bug was first discovered in June of 2008 in the area of Los Angeles, CA, but by September of 2009 has made its way rapidly east, infesting the important winter agricultural areas of the southeast counties in California and into southwest Arizona. Because it now is so widespread it is feared that this destructive insect will now be permanently established in these areas, and likely will continue to expand its range. Where cole crops such as cauliflower, cabbage, or radishes are being attacked some growers are reporting a loss as high as 35% of their crop. In tests to determine the potential for damage the bugs may cause, feeding for less than one week caused as much as 80% of the test plants to be destroyed. They may also feed on “weed” species of mustards, enabling the insects to survive well beyond the agricultural areas that get regular attention, and to survive on these plants that may be present during the winter months. The Bagrada Bug is a very colorful and distinctive insect, although it could be confused with a common native species of stinkbug called the Harlequin Bug – Murgantia histrionica – which also feeds on many ornamental plants and agricultural crops, including the same cole crops of cabbage and broccoli as does the Bagrada. At this time the Harlequin Bug, also called the calico bug or collard bug, is found throughout the southern half of the U.S. These two species can be distinguished by the patterns of red or orange coloring on their wings.
The Bagrada Bug has more extensive black areas, and has a long reddish and white line running down the middle of its upper side, from just behind its head back to the middle of its wings. The Harlequin Bug has much large orange/red patches, especially on each side of its wings, and does not have that obvious single line of color down its back. The adults of each of these species is about the same size, being about ¼ inch in length and of a similar overall shape. The female deposits her 100 or so eggs either in clusters on the leaves or in the soil beneath the plants her offspring will feed on. Turning over the soil after crops are finished, and disposing of spent plants, will help to reduce the numbers of bugs that survive season to season.
As of 2010 the intensive search for effective controls is underway, and unfortunately biological controls (predators and parasites) have not yet been found. Some of the common natural plant-based insecticides also have been shown to be ineffective, and organic farms have often seen the worst impact from the feeding of the bug. Synthetic insecticides currently do show effectiveness and are the choice for eliminating the bugs when they are found in agricultural crops. If anyone finds the Bagrada Bug beyond the range it already is known to infest, you are asked to contact your local Department of Agriculture office to report it. Early detection gives the best opportunity for limiting the spread of the insects and the damage they cause.