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Paul Becher
Researcher at the Department of Plant Protection Biology
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Fly away or stay to control pests?
Published: 11 October 2024
If you release hoverflies in cultivation tunnels to combat aphids, do they stay and protect the crops or fly away? Paul Becher and his research team investigated this in tunnels with commercial raspberry and blackberry production.
Release of hoverflies is an efficient biocontrol method to combat aphids in greenhouses as hoverfly larvae eat aphids.
– But application of hoverflies in open systems like cultivation tunnels is less studied, therefore me and my research team investigated if released hoverflies are loyal to their release site or, migratory as they are, just fly away without providing the service which they were purchased and released for, says Paul Becher.
Marking hoverflies with color pencils
Using water resistant color pencils Guillermo Rehermann and Sheelan Barazanji marked almost 300 hoverflies of the species Eupeodes corollae prior to their release in tunnels of commercial raspberry and blackberry production.
– The marked and released hoverflies could be recorded for several days in company with wild hoverflies on plants with aphid infestation, says Paul.
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One way to combat aphids in greenhouses is to release hoverflies whose larvae will eat the aphids. Photo: Guillermo Rehermann
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Using water resistant color pencils the researchers marked almost 300 hoverflies. Photo: Guillermo Rehermann.
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Not the adult flies, but their offspring is predatory on aphids and biocontrol efficiency depends on reproduction and oviposition of the flies.
– It was therefore rewarding that hoverfly larvae preying on aphids could be recorded after hoverfly release. While it remained unknown if the larvae had wild or marked-and-released hoverfly parents the observations suggest that both release of hoverflies and conservation of wild hoverflies can contribute to aphid control in open cultivation tunnels.
– As a next step we would like to quantify the impact of released hoverflies on the aphids in more detail, concludes Paul.