Description
Orius is a predatory bug that feeds on many species of small, soft-bodied insects and pollen. Adults are 1/10 inch long, mostly black with lighter markings on the wings. Nymphs are colorless when they hatch, darkening to yellow, then to dark brown as they grow. They grow from 1/50 inch long up to over 1/10 inch long. All stages or Orius move very quickly. The adults are good flyers and move efficiently throughout a greenhouse to locate prey. Adults are attracted to, and often found in flowers.
Target Pest
Western flower thrips (Frankliniella occidentalis) and Onion thrips (Thrips tabaci).
Life Cycle
A complete life cycle takes approximately 3 weeks at 70°F. Cooler temperatures, and lack of prey, slow development. Sex ratio in the population is about equal, with slightly fewer (45%) females. Females lay 2 eggs per day, with an average of 30 eggs in their lifetime. Eggs are laid in plant tissue (main stem, leaf vein, flowers or petioles) with the top of the egg sticking out of the leaf. Eggs hatch in 4-5 days. Orius nymphs grow through 5 instars over 2-3 weeks and adults live for 3-4 weeks. Orius will diapause in the fall, when day lengths are less than 13 hours.
Orius pierces its prey with its mouthparts and sucks out the body fluids. If prey is abundant, Orius kills more thrips than it needs to survive. Pollen is an alternative food source for Orius and will favor their development and reproduction.
Use in Biological Control
Orius has been shown to be effective control for western flower thrips in cucumber and sweet pepper greenhouses. It is not effective for thrips control in tomatoes. Orius are generalist predators that consume a variety of pests including mites, aphids, and small caterpillars. They are most effective for pests with life stages that inhabit flowers (such as flower thrips). Optimum conditions are temperatures over 59°F with relative humidity over 60%. Typical greenhouse temperatures of 64°-82°F and humidities are suitable for Orius development.
Monitoring Tips
Orius adults and older nymphs are easy to see in cucumber and pepper flowers, where they are feeding on thrips and pollen. Both adults and younger stages can be found on leaves and along stems, but they are more difficult to find.
Product Information
Orius are usually sold as adults, packaged in containers with buckwheat hulls or other materials. This provides the adults with hiding places, which reduces cannibalism during shipping. Release the adults by gently shaking them onto individual plants or by opening the containers in the greenhouse and allowing the insect to disperse.
Introduction Rates
Orius needs a food source before they can lay eggs, therefore they should only be released when thrips are present or when pollen is available. Pollen can include flowering crops in the greenhouse and/or supplemental food such as Nutrimite, Wheast, Artemia.
2,000 -4,000 Orius /acre
.5 Orius/plant or .05-0.1 Orius/sq. ft.
Apply weekly for two weeks or 1-4 Orius/plant in hot spots.
Control is achieved proportionately sooner with higher release rates. Four to six weeks are required after release of Orius before thrips populations decline markedly.
Note: Orius adults are attracted to yellow sticky traps, however, if traps are placed at a a rate of 1 trap/100 plants or more, this should not be a problem. When more than 4 Orius are being caught on traps per week, it is an indicator that their density is high and that enough Orius are in the crop to bring thrips under control.
For Best Results
Until thrips populations are established, use the predatory mite Amblyseius cucumeris for thrips control. To prevent Orius from diapausing from mid-August through March, supplemental lighting must be provided to increase day length to 14 hours or longer.
Using Chemicals
Avoid the use of systemic insecticides or pesticides with long residual action.
Content Courtesy of Applied Bio-nomics Ltd
