A Comprehensive Guide to
Safe Biological Pest Control
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Although pirate bugs (Orius) appear to have preferences for particular prey, they are general predators and will consume a variety of pests including mites, thrips, aphids, and small caterpillars.
Adult minute pirate bugs are small, 2-5 mm (1/12 to 1/5 inch) long, oval, black to purplish with white markings, and have a triangular head. Adults can be confused with plant bugs in the family Miridae, which are generally larger, have longer antennae, and only have one or two closed cells in the tip of their forewings. Minute pirate bugs undergo incomplete metamorphosis, and nymphs are usually pear-shaped and yellowish or reddish brown with red eyes. Eggs are inserted into plant tissues where they are difficult to detect. Developmental time for minute pirate bugs is very short, only 3 weeks from egg to adult. They are generalist predators and are often the first and most common predaceous insects to appear in the spring. Minute pirate bugs are common insect predators in many crops including alfalfa, corn, small grains, cotton, soybeans, and tomatoes as well as on ornamentals and landscapes. Adults and nymphs feed on insect eggs and small insects such as psyllids, thrips, mites, aphids, whiteflies, and small caterpillars.
The total gereration time for Orius in greenhouses (70 deg F) is approximately 3 weeks. Eggs are laid in plant tissue (main stem, leaf veins, flowers or petioles) with the top of the egg sticking out of the leaf. The eggs hatch in 4-5 days and grow through 5 stages.
All stages move quickly and adults are good flyers. They will move efficiently throughout the greenhouse to locate pests. Orius kills its prey by piercing them with its mouthparts, and sucking out the body fluids. If prey is abundant, Orius kills more thrips than it needs to survive. The generation time is affected by temperature and food sources. Cooler temperatures slow development, and the presence of pollen appears to have a favorabe effect on its development.
Release 100 to 2,000 Orius per acre. For greenhouse cucumbers, release 1 Orius per 2 plants for the whole greenhouse or 1 to 4 Orius per plant in hot spots, where thrips populations are established. It is recommended to release a minimum of 200 to 500 at one time even for smaller areas.
Aphidius is a small parasitic wasp, native to North America. About 100 eggs are laid in aphids which the larvae subseqently develop. At 77 degrees F, 10 days are required from egg to adult for Aphidius. At 70 degrees F, two weeks are required fro development on the parisite. Up to 200-300 aphids are attacked be each female. Fertilized eggs develop into females, nonfertilized eggs develop into males. There are usually twice as many females as males.
Aphidius is shipped as parasitized aphid mummies from which adults will emerge, or as newly emerged adults. Apply 500 to 3,000 Aphidius per acre, 2 to 3 times, one week apart.