Graduate student Lessando Gontijo nets syrphids to measure their attraction to sweet alyssum.
(Photos by Betsy Beers, WSU)
The researchers recently published their study in the journal Biological Control. They found that plantings of sweet alyssum attracted a host of spiders and predator bugs that in turn preyed on woolly apple aphids, a pest that growers often control with chemical sprays.
|A syrphid hovers over alyssum.|
Researchers compared plots of apple trees with sweet alyssum to plots without flowers. While the sweet alyssum attracted hoverflies, as desired, Gontijo and colleagues found few hoverfly larvae, showing that the hoverflies had only a marginal effect on the aphid population.