The American Floral Endowment recently released new research from North Carolina State University where researchers describe how aphids can be managed by releasing the parasitoid wasp Aphidius colemani.
The American Floral Endowment (AFE) recently released new research from North Carolina State University (NCSU) where researchers describe how aphids can be managed by releasing the parasitoid wasp Aphidius colemani in Optimizing Banker Plant Systems for Aphid Biological Control in Floriculture Greenhouses , Research Report #217. This report explains how using banker plants is an environmentally friendly way to sustain the parasitoid with alternative hosts, removing the need to repeatedly purchase new parasitoids.
“Aphids can murder profits for growers, wholesalers and retailers by feeding on crops and leaving them unmarketable,” said Eric Nissen of Sunshine State Carnation Inc. and AFE Production and Post-Harvest Research Committee chairman. “Fortunately, researchers address this in a new report that discusses how to use banker plants in a pesticide-free approach to economically kill aphids dead.”
But what exactly is a banker plant system? Banker plant systems use plants as an “arsenal” for predatory insects that can feed on the pests that murder both crops and profits. Banker plant systems consist of a grain plant (wheat, barley, etc.) that supports non-pest aphids, and those aphids support parasitoids, which in turn attack pest aphids in the crop.
“Banker plant systems have never been developed to the point where people can implement them easily or where there’s actual recommendations for a formula to tell people to grow these kinds of plants or exactly how to do it,” said Steven Frank, Ph.D., NCSU assistant professor and research leader. “Our overall goal was to better understand banker plant systems and to address these concerns.”
Which banker plant species produces the largest, most fertile parasitoids in the shortest time?
The researchers tested three cultivars each of barley, rye, wheat and oats and found barley to be the most reliable species for banker plants, with rye being the worst. Fortunately, barley is widely available, the seeds are inexpensive and it grows quickly.
What are the optimal implementation practices for aphid banker plant systems?
In greenhouses, plants infested with pest aphids were placed 10, 20 and 30 feet from banker plants to determine how many aphids were parasitized at each distance. Researchers found parasitoids traveled more than 30 feet to find pests. Thus, banker plants could be spaced 60 feet apart in greenhouses and maintain effectiveness.
How effective are banker plant systems for aphid control in commercial greenhouses?
In both large research greenhouses and commercial greenhouses, banker plant systems provided a higher level of biological control when compared to releasing parasitoids without banker plant systems. Banker plants effectively kept pest aphid counts low.
No insecticides are required when using banker plant systems, and biological control methods like this can be applied during the flowering period of sensitive plants.
“Biological control is not finicky or unreliable, and many greenhouses today are using environmentally-friendly biological control as their only pest management tactic and spending less or the same amount of money as when they were using pesticides,” Frank said. “Banker plant systems also provide the opportunity to market plants differently and hopefully get a premium price for offering organic or pesticide-free plants.”
The new research is being tied to AFE's recent Murder, Sex and Greed campaign  i.e., killing aphids (murder).