Pesky stable flies may have met their match. Researchers at the University of Nebraska-Lincoln and USDA's Agricultural Research Service are testing tiny parasitic roundworms as biological control agents. They want to determine if the roundworms, also called nematodes, can provide cattle producers a reliable alternative to chemical insecticides.
In experiments, up to 99% of fly maggots died within 48 hours of infection by S. feltiae, the researchers' top fly fighter. The nematode kills the flies' maggot offspring by wriggling into their bodies to feed, mate and reproduce.
The research primarily targets stable flies because they cost U.S. beef and dairy cattle industries up to $1 billion in annual production losses. The biting flies cause blood loss, stress and feed efficiency problems.
So far, researchers have screened about 20 species and 50 strains of fly-infecting nematodes. They're particularly interested in those capable of surviving in manure around feedlots or soiled bedding in calf pens, where 80% of the flies' brood hatch and feed.
One of the drawbacks to controlling flies with chemical insecticides is that they must be reapplied as fly populations rebound or migrate from other areas. In addition, the emergence of insecticide-resistant fly populations is a concern.
For more information, check out the July issue of Agricultural Research magazine, available on the Web at www.ars.usda.gov/is/AR/archive/jul02/flies0702.htm.
Some girl wasps just wanna kill flies. And that fact may eventually bring livestock producers a biocontrol tool for flies, according to researchers at the Lethbridge Research Centre in Alberta, Canada.
Scientists there are investigating the potential of the bacterium Wolbachia to cause female-biased sex ratios in species of tiny wasps that are natural enemies of house and stable flies.
The effect of Wolbachia in producing more female wasps could provide increased fly control, researchers say.
Here's how the process works: Female wasps lay eggs in fly pupae, the eggs hatch, and the wasp larvae feed on the developing fly. These wasps eventually emerge as adults from the dead fly pupae and go on to repeat the cycle, killing more developing flies.
The ultimate goal, researchers say, is to use Wolbachia to produce all-female wasp populations that could be released to control flies.
At this point, scientists are trying to identify the strains of Wolbachia by their DNA, pinpoint the effects that each strain may have on an insect, and then select the best strains for targeted and effective pest control strategies. Researchers hope to find a strain that causes all-female offspring, which would allow all-female populations of wasps to persist generation after generation.
What's more, because Wolbachia is widespread in many insect pests throughout the globe, this fundamental DNA research has broad implications. Wolbachia is thought to infect 20-70% of all known insect species, and researchers say they are only beginning to learn what the bacterium can do.
For more information, contact George Kyei-Poku at 403/317-2232 or visit www.agr.gc.ca/science/lethbridge.
“Feeder Research” is compiled by Diana Barto, [email protected].