7 Things You Need To Know About The Bagrada Bug

[blackoutgallery id=”71967″]

Advertisement

Bagrada bug (Bagrada hilaris), a species of stink bug also known as “painted bug,” is a major concern on vegetables, especially on Brassica crops such as broccoli, cauliflower, and turnip.

Stink bugs are one of the most important pests worldwide and have caused economic losses to several agricultural crops. The name “stink bug” originates from the offensive odor the bugs discharge from the glands located in the base of the last pair of legs when disturbed. Stink bugs have a straw-like mouthpart which houses four needles.

The bagrada bug, in particular, is native to Southern Africa, the Middle East, and Asia, and was accidentally introduced to Southern California. It is now established in Southwestern states in the U.S. This pest has some unique features, which separate it from other stink bug species.

The bagrada bug arranges and rearranges the four needles in its mouthpart to inject saliva into the plant material, partially digesting it, and sucking the digested juice causing injury to plant cells.

Top Articles
Have a Plan For Climate Change? Why Fruit Growers Need To Act Now

This feeding injury affects normal development of the surrounding cells resulting in deformed fruits and plants. Often, the pest feeds on the most nutritious parts of the plant such as the seeds. The injured seeds then abort the fruit development.

Want to keep bagrada bug at bay? Click on the next page to read seven pointers to help you keep this pest from taking over your fields.

  1. Brassica plants are the preferred food. The bagrada bug prefers Brassica plants although it also feeds on non-Brassica plants. It feeds on all plant structures such as seeds and leaves. One interesting behavior of the pest is its ability to precisely locate and feed on the germinating seeds planted in the soil. This behavior results in the seedling emerging out of the soil with feeding injury.
  2. Females lay eggs in the soil. Generally, stink bugs lay eggs on the above-ground structures of the plant, such as the leaves or stems. The bagrada bug, however, can lay eggs in the soil. The females push their eggs a few millimeters below the soil surface, but the exact reason for this behavior is not clear. It’s theorized the eggs are better protected from predators, parasites, or even from desiccation when they are laid in the soil.Plus, the bagrada bug lays eggs singularly, rather than in a cluster or group. Other native stink bugs, such as the brown marmorated stink bug and the consperse stink bug, lay eggs in clusters.These behaviors might be an adaptation to survive the dry and hot environments where they naturally occur. These two egg laying behaviors work in favor of the bagrada bug’s quick geographic distribution and dispersal, because plant transplants (with soil) are often moved within and across state borders.
  3. Soil is used for shelter. Bagrada bugs find shelter in the cracks and crevices of the soil within the field. When night and day temperatures are on the cooler side, they stay in the soil near the plants. The pest colonizes the soil as the seeds are planted and reproduce as the plants grow. It is unclear if the nymphs colonize along with the adults.
  4. Aggregation occurs in high numbers. Bagrada bugs tend to aggregate in high numbers on few plants. Some plants are impacted with severe feeding damage and appear stunted, whereas others are spared with no or limited damage. This suggests these bugs emit some sort of aggregation pheromone which attracts other bagrada bugs.The aggregation behavior often results in severe damage on plants. Typically, bagrada bug adults invade from outside the field and mostly settle in the border zones of the field. As a result, the plants in the border zones appear stunted, and the plants look healthier toward interior zones of the field.
  5. Bugs drop when disturbed. Bagrada bugs will drop to the ground when disturbed, and it’s thought the noise or vibration of the approaching spray equipment may alert the bugs that are active on the plants.This “drop” behavior may have consequences on efficacy of insecticide sprays, especially when the insecticides break down rapidly, as in the case of a few organically approved insecticides. It’s unlikely that the residues will provide extended plant protection from bagrada bug feeding. The drop behavior may also affect growers who use vacuums to suck up the bagrada bugs from the plants. The bugs might drop and move into the cracks in the soil as the vacuum approaches the plant.
  6. Bugs are not so stinky. Unlike some other stink bug species, the disagreeable odor from bagrada bugs is not clearly noticeable when disturbed. It is assumed that stink bugs emit odor to distract and dissuade predators from predation.
  7. Walking, not flying is preferred. Adult bagrada bugs are often found walking on the soil surface rather than flying. On most occasions adult bugs are found copulating.

Clearly, the bagrada bug is unique in many ways. In the Central Coast of California, based on observing bagrada bug for the past two years, very low densities or none were seen during the spring and early summer.

Toward the end of June, their populations gradually increase and become visible on Brassica weeds. By the end of July and onward, high numbers were seen on Brassica crops with apparent damage. As the weather shifts toward the cooler side and with arrival of few rain storms, their populations almost disappear in December.

8