New insect threatens South Texas vegetable crops

AgriLife Extension experts: Bagrada bug could spread throughout the U.S.  

WESLACO  —  Yet again, another insect pest has moved into South Texas with the potential to damage crops and spread to other parts of the nation, according to experts at the Texas A&M AgriLife Research and Extension Center at Weslaco.

“This one is called the bagrada bug, a stink bug that will affect primarily our winter vegetable crops,” said Dr. Raul Villanueva, a Texas A&M AgriLife Extension Service entomologist in Weslaco. “It comes to us from Mexico, but unlike many other invasive species, it was first reported in California then El Paso, moved into Mexico, then to the Rio Grande Valley.”

A native of Africa, the bagrada bug was first detected on the U.S. West Coast in 2008.

“South Texas is a gateway for invasive species that can spread throughout the country,” Villanueva said. “We often serve as a first responder, alerting growers in other areas of the nation of what may be coming.”

Growers outside South Texas would be wise to watch for this one, he said.

“The question is, how far will it spread from here?” Villanueva said. “That it was able to make its way out of El Paso, where we thought it was geographically isolated, tells us that it could quickly make its way to the Gulf Coast states and the Eastern U.S.”

The bagrada bug has the capability of flying, but likely made its way here via commercial transportation, Villanueva said.

“This insect affects a lot of brassicas, including cabbage and broccoli, two very important crops in South Texas, as well as radishes, Brussels sprouts, kale and others. They feed on leaves and fruit and can cause major crop damage.”

Other host plants include tomatoes, figs, peppers, nursery plants and even grain sorghum, though Villanueva said it will likely not pose a threat to either sorghum or corn.

Dr. Juan Anciso, an AgriLife Extension fruit and vegetable specialist in Weslaco, said the bug can be easily controlled with insecticides, but growers need to keep an eye out for it before it’s too late.

“These insects move quickly,” he said. “Often, by the time a grower notices the bagrada bug, the damage has already been done. These insects can totally destroy a plant or leave it too damaged to produce a crop.”

The bugs lay their eggs on the soil near vegetable crops; immatures then move into the leaves, which serve as their food source.

“This insect is probably a cousin to a stink bug we already have here, the harlequin, but it’s smaller and less colorful,” Anciso said. “And it damages crops like the harlequin does. The harlequin is called a fire bug because it leaves foliage looking as though they’ve been exposed to fire, brown and damaged.”  

Eventually, biological control will play a role in keeping bagrada populations in check, Villanueva said. It’s natural enemies are already here; they’re just not yet accustomed to the newcomer.

“These natural enemies need some time to adapt to this new pest,” he said. “Unlike the harlequin, the bagrada lays its eggs on the soil, so it’s more difficult for the natural enemies to prey upon them. But I suspect they’ll eventually learn to prey on and parasitize the bagrada.

“And of course, we have several growth regulators and pyrethroids that are already labeled for effective control. Growers just need to be on the lookout for this pest,” he said.

Research is now being conducted on the bagrada’s biology, and information about its life cycle and control will be discussed with growers at upcoming field days.