Minute Pirate Bug, Thrips Predator
by Syngenta Bioline
PO Box 1555, Ventura, CA 93002
800-248-2847 * 805-643-5407 * fax 805-643-6267
Western flower thrips (Frankliniella occidentalis)
Onion thrips (Thrips tabaci)
‘Orius’ is a predatory bug (Family Anthocoridae) that feeds on many species of small, soft-bodied insects.
· Adults are 2-2.5 mm (1/10 inch) long, mostly black with lighter markings on the wings.
· Nymphs are colorless when they hatch, darkening to yellow, then dark brown as they grow. They grow from 1/50 inch (0.5 mm) long up to1.8 mm (<1/10 inch) long.
All stages of 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.
Use in Biological Control
· Orius has been shown to be an effective control for western flower thrips in cucumber and sweet pepper in greenhouses (flowering plants that produce pollen. 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 (15° C) with relative humidity over 60%. Typical greenhouse temperatures of 64-82° F (18-20° C) and humidities are suitable for Orius development.
· Orius lays a large proportion of its eggs in (side) shoots. Avoid unnecessary loss of these eggs by introducing after removing side shoots.
· Native to North and South America
· 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.
· Thrips shrivel after being eaten by Orius, and are therefore difficult to see in the crop.
A complete life cycle takes approximately 3 weeks at 70° F (21° C). Cooler temperatures and lack of prey slow development.
· Sex ratio in the population is about equal, with slightly fewer females than males (45% females).
· Females lay 2 eggs per day, with an average of 30 eggs in their life time. 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. Females stop laying when the daylight is less than 12-14 hrs.
· Orius nymphs grow through 5 wingless instars over 2-3 weeks, until they molt to the adult stage. Adults live for 3-4 weeks.
· Orius will diapause in the fall, when day lengths are less than 11 hours.
Orius pierces its prey with its mouth parts and sucks out the body fluids. If prey is abundant, Orius kills more thrips than it needs to survive. The presence of pollen favors development of Orius as it acts as an alternate food source.
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 insects to disperse.
Orius need a food source before they can lay eggs, therefore they should only be released when thrips populations are present or when pollen is available (i.e., from flowers of sweet peppers) in groups of 25-50 insects to encourage mating
General Introduction rates
· 2,000 - 4,000 Orius/acre (5,000 - 10,000 Orius/hectare) use higher numbers in hotspots.
· Greenhouse cucumbers - 0.5 Orius/plant or 0.5/10 ft2 (m2), weekly, for 2 weeks.
or 1 - 4 Orius/plant in hot spots, when thrips populations are established.
· Sweet peppers - 2 - 3 Orius/10 ft2 (m2) in hot spots. Two releases, spaced 2 weeks apart will usually establish Orius throughout the greenhouse.
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 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 enough Orius are in the crop to bring thrips under control.
For Best Results
· Until thrips populations are established, use the predatory mite Cucumeris (Amblyseius cucumeris) on cucumber. On pepper use the predatory mite Degenerans (Amblyseius degenerans) as soon as pollen is present.
· To prevent Orius from diapausing from mid-August through March supplemental lighting must be provided to increase day length to 14 hours or longer.
For effects of pesticides on Orius see Pesticide Toxicity page.
Avoid the use of systemic insecticides or pesticides with long residual action.