Tip Top Bio-Control Technical Bulletin

Atheta coriaria Kraatz
Parasitic wasp

Target Pests:
Shore flies (Ephydridae), Fungus gnats (Sciaridae), Western flower thrips (Frankiniella occidentalis).

Description:
Atheta coriaria are light to dark brown in color; adults are 3 - 4 mm long and are slender with short wing covers. Rove beetles have an interesting habit of curving the abdomen upwards like scorpions and can run or fly when disturbed.

Atheta coriaria is a native species of soil-dwelling rove beetle which feeds on small insects and mites (e.g., shore flies, fungus gnats, moth flies, springtails, root mealybug crawlers, aphids, spider mites). Both adults and larvae are aggressive active predators and are attracted to decomposing plant or animal material and algae where their hosts are found. Since they actively fly, they rapidly colonize the release area.

Product information:
Atheta is available in peat/vermiculite media in bottles of 100-500 adults. Inspect on arrival to check the product for live Atheta. The adults may be seen moving in the media. They are active fliers so do not open containers until in the release area. Atheta should be applied as soon as received. If necessary, containers can be held at 10°C (50°F) for up to 7 days.

Life Cycle:
The complete life cycle takes 21 days at 21°C (70°F) . The eggs hatch in 3-4 days into young larval stages. Each Atheta consumes 10-20 prey per day. The larvae resemble the adults, pupal chambers are constructed out of silk. Adults live for 21 days and are non-diapausing under greenhouse conditions. Atheta populations will naturally fuctuate throughout the growing season depending on host numbers.

Release Rates:
Soil Culture, Sawdust bag or rockwool culture: Apply 1/sq. m (10 sq. ft.). Release throughout the greenhouse at a rate of 100-500/greenhouse weekly or biweekly (depending on greenhouse history of shore flies and fungus gnats) until a total of 1/sq. m. (10 sq. ft) of total greenhouse area are released. To ensure reproduction and mating, release 50-100 in one spot in the center of the release area. Be sure to treat areas with wet, exposed area of soil, where fungus gnats and shore flies are likely to breed.

Atheta is most effective while numbers are still low (below 10/trap/week), or when applications are started before fungus gnat population becomes well established. One application of Atheta per crop cycle is usually sufficient if started early in the season.

Strategic Considerations:
It is likely that foliar sprays are less harmful than soil drenches depending upon how much pesticide reaches the soil surface. Microbial pesticides, such as Vectobac® (BTI) will not harm Atheta.