How do predatory row beetle, Atheta coriaria control insect pests?

Seven facts about predatory row beetles, Atheta coriaria –

1. What are predatory row beetles, Atheta coriaria

  • Predatory row beetles, Atheta coriaria are soil-dwelling beetles and have been used as an excellent biological control agent for the control of various soil-dwelling insect pests (see below) that cause a serious damage to many economically important crops grown in the greenhouses and gardens.
  • These predatory insects are taxonomically considered as beetles but they don’t look like beetles as they have 3-4 mm long and narrow brownish- black color body with short and indistinct eletra (fore wings).
  • These beetles are capable of flying but you only notice them especially when they are running on the ground or their abdomens typically curved upward, like a scorpion when disturbed.
  • Both larvae and adults of row beetles look alike except that adults have two pairs of wings.These predatory beetles are naturally found in North America but also commercially available for application in the greenhouses and vegetable gardens for control of small insects.

2. Predatory Row beetles, Atheta coriaria are effective against following insect species

3. Key factors for predatory row beetles, Atheta coriaria effectiveness

  • Both adults and larvae of Atheta coriaria beetles are predatory in nature and they have an ability to consume over 10-15 host insects per day.
  • Both adults and larvae of Atheta coriaria are very active and attracted to decomposing plant material or organic matter where they can find their hosts.
  • Atheta coriaria predatory row beetles have ability to colonize rapidly after application.
  • Atheta coriaria predatory row beetles can easily adapt in various types of potting media including nursery-mix, pro-mix and coconut fiber.
  • Since Atheta coriaria row beetles are opportunistic predators, they remain fairly high in numbers in the greenhouse with a gravel floor or raised beds, or in a garden with lots of organic matter after application. This means you do not have to re-release them more often, which can save you money and time.
  • These predatory row beetles are happy and perform well against fungus gnats, shore flies and mealybugs in the greenhouses or gardens when temperature is between 67-78°F and a relative humidity between 40-99%.
  • Since adults of predatory row beetles are capable of flying, they can easily disperse to new host infested area in the greenhouse where they can colonize.

4. How predatory beetles Atheta coriaria are applied in the greenhouses or gardens

  • Atheta coriaria are shipped as ready-to-release adults.
  • Predatory row beetles should be released immediately after their arrival but for any reason, if you are not ready to release, you can store them in a cool place at 10°C (50°F) for at least a week without affecting their effectiveness.
  • It is advisable to check the viability of row beetles before releasing them in the greenhouse or garden. If they are alive, you will be able to see their movement in the containers. Since row beetles, Atheta coriaria are very aggressive fliers, care should be taken that the containers should be opened only in the area where row beetles are supposed to be released.
  • For effective control of insect pests like fungus gnats, shore flies and mealybugs release predatory row beetles, Atheta coriaria by opening containers in the greenhouses when population pressure of fungus gnats or other host pests is very low.
  • It is recommended that the predatory row beetles, Atheta coriaria should be released throughout the greenhouse or garden at the rate of 3-5 adults per square meter area (i.e. per 10 square foot area). However, if population pressure of fungus gnats or other host pests is very high, release over 10 row beetle adults per square meter area.

5. How predatory Atheta coriaria row beetles work in the greenhouses or gardens

  • Atheta coriaria are shipped as ready-to-release adults.
  • When predatory row beetles are released in the greenhouses or gardens, they can easily disperse throughout the greenhouse or garden by crawling on media substrate or by flying.
  • Then they actively search for their hosts and rapidly colonize in the release area.
  • Both larvae and adults of row beetles are predatory in nature and feed on larval and egg stages of fungus gnats and shore flies, pupae of western flower thrips, all the soil-dwelling stages of mealybugs.
  • Predatory row beetles, Atheta coriaria also feed on aphids and mites but if there is a choice, then they will prefer to feed on larvae and eggs of fungus gnats and shore flies.
  • Depending on the availability of optimal environmental conditions and ample of food supply, these released row beetles can reproduce and complete their egg to egg life cycle within 21 days at 70°F in the greenhouses or gardens.
  • Females of Atheta coriaria lay eggs, which hatch into predacious larvae within 3-4 days. The hatched larvae then immediately starts feeding on their host insects develop through three instars and then pupate in silken chambers. Then adults emerge from pupae and life cycle continues. The temperature and a relative humidity for optimum development and performance of row beetles in the covered crops would be between 67-78°F and 40-99%, respectively.

6. Why you need predatory row beetles, Atheta coriaria

  • they can reduce the crop damage by feeding on all the larval stages of both the fungus gnats and shore flies.
  • they can kill and feed all the soil-dwelling stages including pupae of thrips
  • they can also feed on greenhouse aphids and mites
  • they are able to actively search for their host insects, kill and eat them
  • they can reproduce and continue their life cycle on their insect hosts including fungus gnats, shore flies and mealybugs in your garden after first application
  • they are commercially available and easy to apply in the greenhouses or gardens

7. Why predatory beetles are safer than traditional pesticides

  • they do not damage plants
  • can be used and applied around children and pets
  • do not cause any harm to the personnel involved in their production and application
  • food products are safe to handle and eat when they are treated with beetles
  • they do not harm humans, animals and pollute the environment

Research Papers

  1. Cox, P.D., Matthews, L., Jacobson, R.J., Cannon, R., MacLeod, A. and Walters, K.F.A. 2006. Potential for the use of biological agents for the control of Thrips palmi (Thysanoptera : Thripidae) outbreaks. Biocontrol Science and Technology 16: 871-891.
  2. Jandricic, S., Scott-Dupree, C.D., Broadbent, A.B. Harris, C.R. and Murphy, G. 2006. Compatibility of Atheta coriaria with other biological control agents and reduced-risk insecticides used in greenhouse floriculture integrated pest management programs for fungus gnats. Canadian Entomologist 138: 712-722.