Aphid Biocontrol
Friday, 05 February 2010 15:12
When just starting out using biocontrol agents, many growers first think about using the well known and familiar ladybeetles for aphid control. There are many species of ladybugs, or ladybird beetles. As generalist predators, they feed on wide range of insect pests and mites. Ladybeetles are relatively inexpensive and can be stored in the fridge. However, there are some concerns with using adult ladybeetles to control aphids. Wild collected ladybeetles for sale are field collected from mountainous areas of the west coast states where the beetles migrate and aggregate in large masses. Beetles are highly dispersive and once released in greenhouses, most will leave, providing little or no control. However, some suppliers offer ladybird beetle larvae, which are less likely to fly away.
Another concern is that harvested lady beetles may have been parasitized by a small wasp that develops as an internal parasite and kills them. And finally, Microsporidia, a disease of ladybugs, has also been detected in some shipments.
For more information see:
http://www.learn2grow.com/problemsolvers/insectsanimals/insectsbeneficial/Buying%20Ladybugs.aspx
So, what to use for aphid biocontrol? Most growers are using a combination of parasitic wasps and predatory midges. Aphid biocontrol is a little challenging because the parasitic wasps are host specific so you need to anticipate what aphid species may be a problem for you or use a mixture of parasites and predators. Some suppliers such as IPM Laboratories and Syngenta offer a mix of different aphid parasites. You might begin with a mixture of wasps, Aphidius colemani (for green peach and cotton aphid) and Aphidius ervi (for potato and foxglove aphids) as preventative, or when numbers are low. Another wasp, Aphelinus abdominalis is also used for potato and foxglove aphids. A predatory midge, Aphidoletes aphidimyza, can be used as clean up, but work best, when the days are longer (beginning in April).
For more information, see: Aphid Biocontrol, Time to Plan
Leanne Pundt, University of Connecticut
Tina Smith, University of Massachusetts
