Better beetle sought for salt cedar control

Beetles from Uzbekistan are more prolific salt cedar eatersthan beetles from Greece. At least that's what Texas AgriculturalExperiment Station researchers hope.

Uzbekistan salt cedar beetles being released by the ExperimentStation's entomology department are the same species as those released onthe salt cedar stands near Lake Meredith. They are just from a differentcollection point, said Vanessa Carney, Experiment Station entomologyresearch associate.

Researchers first looked at latitude and longitude to find the beetlethey thought would be best suited to this region, and they came up withsalt cedar beetles from Posidi, Greece, Carney said.

"Because some of the releases in other states haven't been successful,we're starting to think it may be more complicated than that," she said."These beetles from Uzbekistan seem to be most suited to our climate atthe same latitude and longitude."

At the Meredith site, the Posidi beetles released in 2004 have made itthrough two winters and had two summers of success, Carney said. However,because of an early warm-up followed by a cold spell, they seem to be lessprolific this summer and haven't exploded in numbers.

Dr. Jerry Michels, Experiment Station entomology research projectleader, and Carney are making new releases of the Uzbekistan beetle thisyear in the heavy salt cedar stands on private land north of Borger. The new site was selected because of its remote location and because itis not subject to other control methods, such as fire and chemicaltreatments, Carney said.

A total of 25 egg masses have been released at three different sites,all within cages, Carney said. While the Posidi beetles are approved foropen release, the Uzbekistan beetles have not been approved by Animal andPlant Health Inspection Service for open release so they must be enclosedin tents.

The beetles being released into the confined salt cedar trials wereprovided by Dr. Jack DeLoach with the U.S. Department ofAgriculture-Agricultural Research Service at Temple, where other studiesare being done.

Each egg mass had 10 to 30 eggs. Another 60 adults were releasedbetween the three sites, Carney said. Each egg will go through threelarval stages, during which time they feed on the salt cedar, before theydrop into the ground and emerge a week later as a beetle.

"Almost immediately they will start mating and will live for about 30days," she said. "We're doing more extensive work on those figures in ourlab at Bushland. We want to determine how many eggs they lay, the lifecycle times and how many batches of eggs they lay in a lifetime."

Damage is what the researchers want to start seeing, Carney said. ThePosidi beetles at Lake Meredith defoliate small branches, but the damagehasn't been widespread. So far, the Uzbekistan beetles haven't been herelong enough for the scientists to gauge what they can do.

"They just came in May and the first year we don't expect to see majordamage," she said. "But they may defoliate the trees within the cages. Wewere warned that it will go quickly, and we may run out of food within thetents."

Michels and Carney said their Texas salt cedar beetle work is part of alarger study that is looking at beetles from Fukang, China; Crete, Greece;Tunisia, Africa; and Turpan, China.

These four strains of beetles will be released in various sitesthroughout the U.S., with emphasis on establishing them at two Texassites, and in Colorado, Wyoming, Utah and Nebraska.

"What we want to see is the differences of these strains at differentlatitudes," Michels said. "People have released a strain here or a strainthere, but what we want to do is release all of these strains at each siteand maybe then be able to make some decisions that are backed up byresearch."

Ultimately, the study should help determine which strains are adaptedto which latitude, he said. The Crete strain was released from Wyoming toSouth Texas and did not work everywhere. At the same time, some of thesestrains are new and haven't been tested anywhere.

This new widespread study will begin once researchers receive approvalfrom USDA's Animal and Plant Health Inspection Service, Michels said.

Source : Texas A&M University - Agricultural Communications