Orius laevigatus

Orius laevigatus belongs to the family Anthocoridae and is a predator of many small soft-bodied arthropods. It is an important predator in the fight against many economically important pests. It is also recognized as one of the main predators of a major economic pest — the Western flower thrips (Frankliniella occidentalis).

Description

Eggs: Orius laevigatus’ eggs are 0.4 mm long. Adult females lay eggs in plant tissues.

Nymphs: Orius laevigatus’ nymphs are less than 3 mm in length, wingless and have the shape of a drop. Their colour varies from yellow-orange to brown. The first age is slightly yellowish, and later ages become increasingly darker.

Adults: Adults of Orius laevigatus have a length of about 3 mm. They are oval and black with white spots on the wings. The wings extend beyond the abdomen. Adults have a long proboscis, which is used to consume plant juices and eat prey.

Life cycle and biology

Orius laevigatus gives several generations per year. The total development time from egg to adult is approximately 3 weeks. Adult females lay eggs in plant tissues.

The eggs hatch in 6-10 days. Orius laevigatus undergoes incomplete metamorphosis, and nymphs develop over five instars. It takes at least 10 days for the nymph to develop, depending on the temperature.

Adults live for about 3 to 4 weeks. Nymphs and adults are very mobile. When the duration of the day is less than 14 hours, adults go into a state of rest.

Natural environment

Orius laevigatus is common on many agricultural crops, including cotton, peanuts, alfalfa, corn, peas and strawberries, on pastures, in gardens and is successfully used as a means of biological control in greenhouses. It is often found in corn stigmas and is most common where there are spring and summer flowering shrubs and weeds, as it feeds on pollen and plant juices when prey is unavailable. In greenhouses, Orius laevigatus is used as a universal predator, especially on cucumber and bell pepper crops.

Nymphs and adults feed on a variety of small prey, including thrips, mites, aphids, whiteflies, shield beetles, small caterpillars and eggs of various insects.

Although Orius laevigatus is a versatile predator, it prefers flower thrips. It preys on the adult and larval stages of many species of thrips, including  Western flower thrips (Frankliniella occidentalis), Eastern flower thrips (Frankliniella tritici) and Florida flower thrips (Frankliniella bispinosa). The larvae of the Western flower thrips (Frankliniella occidentalis) are the preferred prey of Orius laevigatus.

Economic significance

Orius species have been successfully used as biological control agents against flower thrips in chrysanthemums, cucumbers, sweet peppers, aubergines, and strawberries. The ability of Orius laevigatus to suppress populations of thrips in pepper grown in the field in Florida exceeded the suppressive effect of weekly insecticide use. At a ratio of one predator per 180 thrips, thrips populations were suppressed, and at a ratio of one predator per 40 thrips, thrips populations were controlled below economic thresholds.

Chang Xu and a team of entomologists discovered in 2006 that Orius laevigatus can suppress populations of the two-spotted spider mite (Tetranychus urticae Koch) on legumes. Suppression of the spider mite was achieved when two bugs were released to control the initial density of 40 spider mites. Orius is also an important predator of soybean aphids (Aphis glycines).

Effectiveness

Orius laevigatus is very aggressive – it consumes about 12 thrips a day, but kills much more than he eats. The number of victims reaches 45 individuals.

Both immature and adult bugs can consume 30 or more spider mites per day. As in the case of thrips, it has been observed that Orius leaves the prey before completely eating it in order to attack another mite. Orius laevigatus destroys more victims than is necessary to meet nutritional needs.

It has been proven that additional feeding of Ephestia’s eggs increases the ability of Orius to control thrips. Ephestia’s eggs are more nutritious for Orius than thrips. This contributes to the growth of the Orius laevigatus population, because adult females fed with Ephestia lay more eggs per day and live longer. The population of Orius increases faster than when feeding only with thrips.

The effect of insecticides

The use of most broad-spectrum insecticides, such as pyrethroids, neonicotinoids, organophosphates and carbamates, suppresses populations of Orius laevigatus. However, Orius laevigatus can be preserved through the careful use of insecticides with reduced risk and the adoption of economic thresholds, this is usually more effective than the preventive use of insecticides.

Application

Orius laevigatus is useful in greenhouses, fields, conservatories, and gardens.

Orius laevigatus is commercially available for mass release. The rate of introduction varies depending on the type of culture and the level of infection with thrips. For garden crops, the release rate of 1-2 predators per square meter is usually used. Orius laevigatus is delivered in an adult state.