The lettuce aphid (Nasonovia ribisnigri) is an important pest of lettuce worldwide. Lettuce growers have traditionally used chemicals to control the aphids, but even that can be difficult since the aphids prefer to feed on the lettuce heart leaves. However, there may now be an alternative, according to an article that appears in the journal Environmental Entomology.
Researchers from Aarhus University in Denmark recently evaluated three tiny parasitoid wasps that are commercially available to see if they might be effective against the lettuce aphid. They found that one of the wasps — Aphelinus abdominalis — was effective as a biological control agent, which means growers may have a new, non-chemical tool to help control the aphids.
“The total mortality inflicted by A. abdominalis within a 24-hour exposure period was 51% for the lettuce aphids,” according to the authors. “This study concludes that A. abdominalis has the potential to be used against N. ribisnigri in inoculative biocontrol programs.”
The other two parasitoids — Aphidius colemani and Lysiphlebus testaceipes — were ineffective against lettuce aphids, but the researchers did find them to be of some use against green peach aphids (Myzus persicae).
Although A. abdominalis were effective against lettuce aphids in the lab, the Danish researchers believe that more research needs to be done to determine whether they will actually work in the field.
“Because N. ribisnigri has a preference of feeding on heart leaves of lettuce, it may be difficult to access for A. abdominalis,” they wrote. “Additional investigation on the influence of plant architecture on host finding is crucial.”
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