What is in this article?:
- The western cole crop industry is gaining much needed information to manage the bagrada bug insect in cole crop seedlings, thanks to researchers at the University of Arizona and the University of California.
Fun and fellowship at the California Association of Pest Control Advisers’ Agri-Expo. Seated from left - Mike Mendoza, Sandy Creighton, and Jason Haught. Standing, from left: Larry Liggett, Greg Hallquist, Jose Silva, Riley Reynolds, and Robert Hornyak.
Bagrada a devastating pest
The pest enters the field when the seed is pegging before stand establishment.
Palumbo said, “I’ve seen them knock out plants and suck them dry resulting in desiccated cotyledons.”
He believes a volatile chemical in the plant attracts the bagrada insect.
On the biology side, the bagrada bug is a very small stink bug from the Pentatomidae family; also known as the painted bug and harlequin bug. Yet the bagrada is about half the size of the harlequin.
Bagrada is about the same size as the sevenspotted lady beetle and one fourth the size of the Say’s stink bug. The female bagrada is slightly larger than the male.
The bagrada has a typical five instar stink bug life cycle. The small egg is about the size of a cabbage looper or corn earworm egg. Through the instar progression, the insect’s body gets darker in color with more orange, white, and black.
The bagrada bug is a warm season pest which thrives in the heat. Optimum average temperatures for bagrada growth range from 86-95 degrees Fahrenheit in the Desert Southwest in July, August, and September. As the temperatures cool off, the insect’s biological development slows.
“In the desert, this is a warm-season pest that infests a cool-season crop,” Palumbo said.
The pest attacks the underside of leaves during the day, and hides at night in the soil and under dirt clods.
The bagrada bug can quickly destroy a seedling. In Palumbo’s trials, a single insect placed on a cotyledon killed the plant in about 60 hours under laboratory conditions.
In another lab test, small pots were lined up in a row, each containing one of 12 different vegetable seedlings. The bagrada passed right by the head lettuce to feast on cole crops. Its feeding favorites include green cabbage, red cabbage, and radish.
“We like to say the bagrada bug has never met a brassica plant species it won’t attack or feed on. There is a lot of truth to that,” Palumbo told the PCA crowd.
If the plant lives, the damaged plant develops multiple unmarketable small heads instead of a single large marketable head or floret.
Palumbo added, “One grower suggested developing a market for baby cabbage. This is a good idea, but unfortunately sometimes the plant won’t even grow a head the size of your fist.”