2014 Highlights: UC IPM Annual Report
Black-Colored Traps Capture the Most Bagrada Bugs
Traps were painted different colors to see which trap color caught the most bagrada bugs. (Photo by S. Joseph)
IN BRIEF
- Bagrada bug feeding causes economic loss in broccoli, cauliflower, and cabbage crops.
- Finding the right monitoring technique is the first step to understanding bug biology and learning how to prevent feeding damage.
- Joseph?s research found that black traps catch the most bagrada bugs.
Bagrada bug is a new pest that feeds on cruciferous plants: broccoli, cauliflower, cabbage, kale, arugula, and collards. In the Salinas Valley, brassica crops are valued at more than $485 million and grown on more than 85,000 acres. Bagrada bug causes severe damage and economic loss, especially in young plants. As a new pest, there is no information on what numbers are out there and when they are most active in coastal brassica crop production areas of California. Having the right monitoring technique is an important first step to gather that information to prevent bug damage and yield loss.
UC IPM Advisor Shimat Joseph tested different colored traps to see which trap caught the most bagrada bugs. He painted different traps white, yellow, red, purple, or black and set them out near fields with bagrada bugs. “Yellow traps are most commonly used for monitoring hemipterans,” said Joseph. But his research results did not support this for bagrada bugs. What he found is that black traps captured almost twice the number of adult bagrada bugs than purple, white, or red traps. Yellow traps actually caught the fewest number of bugs.
Joseph also recorded nymph numbers for each trap color. The number of nymphs captured in each colored trap were not significantly different, but black traps captured more than the other colors.
Joseph’s research determined that black is the best trap color to catch the most bagrada bugs. Researchers can now use black traps to learn more about the life cycle and movement of bagrada bugs. Understanding the biology of a pest is the first step in developing an IPM program. Effective monitoring techniques can be used to make management decisions and ultimately protect brassica crops from bug feeding.
In 2008 bagrada bug was first detected in Los Angeles, the first for North America. Since then it continues to spread up the California coast and has been reported in Nevada, New Mexico, and Utah. Feeding on young plants causes the most damage. Injury causes economic loss when the seedling's apical meristem is damaged, resulting in multiple heads or no heads developing. Desiccation or wilting of the plant also occurs.
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