Biocontrol agents for stable flies
Stable flies are major pests of cattle in dairies and feedlots. The adult flies are active throughout the summer and inflict painful bites on the legs of cattle. Economic losses result from this irritation.
Unfortunately, the stable fly is exceedingly difficult to control, even with chemical insecticides. Research at the Agriculture Canada Research Centre at Lethbridge is focused on developing integrated pest management strategies to reduce the need for pesticides.
Researchers are studying the potential of native biological agents to control stable flies.
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One of the potential agents is a small parasitic wasp. These small wasps, less than three millimetres long, lay their eggs on the pupae of stable flies. The eggs hatch, and the wasp larvae destroys the fly pupae by feeding on them. The wasps provide fly control in poultry and swine facilities and to a limited extent in feedlots and dairies.
However, little information is available on their activity or abundance in confined cattle systems in Canada.
In two years at four dairies in southern Alberta, the station found seven wasp species. These do not occur in large numbers in nature, but they can be reared indoors and released. Laboratory colonies of both these tiny wasps have been established.
The most promising species, Muscidifurax zaraptor, can infest 70 to 80 percent of stable fly and house fly pupae when the ratio of wasps to pupae is one to 10. A single female wasp can lay enough eggs to parasitize as many as 16 fly pupae in 24 hours.
The Lethbridge station is working to find economical mass-rearing techniques and effective release strategies so stable flies can be successfully controlled through an integrated pest management program.
- Agriculture Canada
‘Sprigging’ saline soil
LETHBRIDGE, Alta. (Special) — Sprigging may be the answer to establishing forage crops in saline areas if costs are reduced, said a provincial cereals specialist.
Sprigging is a method of transplanting roots or rhizomes of grasses deep in the soil, usually below the area of salt concentration which can kill plants. At the 10-cm depth, the grass is placed in moist soil which promotes growth.
But Jack Payne, a cereals and oilseeds specialist in Taber, said sprigging may be prohibitive because of the cost. Sprigging required 8.6 man hours per acre on a southern Alberta test site. Seeding required 1.5 man hours per acre.
Because of a shortage of sprigging material, only 1.5 acres of Garrison creeping foxtail was transplanted. It cost $585.50, or $390.33 per acre.
The cost to seed the plots was $94.65 per acre.
Initial work shows forage establishment by sprigging will have to be significantly better than seeding grasses to justify the high costs, said Payne.
The sprigged creeping foxtail produced plants which were more mature than those which grew from seed. By August, sprigged plants had headed out while seeded plants were only seedlings.
He said the site will be monitored through 1995 to determine forage establishment.
