Fungal baits offer hope for spotted-wing Drosophila biological control

An insect-devouring fungus shows promise in the control of spotted-wing Drosophila, a pest of soft fruit, according to Dutch researchers.

Wageningen Plant Research claims that a new isolate of Metarhizium robertsii "reduces reproduction of fruit flies very effectively".

After four weeks in cages with a small dish of a blueberry-fungus mix there was "virtually no reproduction" of the fruit fly Drosophila suzukii compared to a control treatment, researcher Rob van Tol said. Two parallel tested fungal products had less or no effect on reproduction.

Other biological control options for this fruit fly are in research, and while some promising parasitic wasps are found in Japan and China where the fly originates, Van Tol said, but added: "It is unlikely that these non-native natural enemies will get a registration in Europe.

Meanwhile native European parasitic "are so far not effective enough to control the pest", he said, leaving entomopathogenic (insect-lethal) fungi as a possible alternative.

But compared to existing commercial products of this type, "it needs faster working fungal strains and a different application strategy whereby young/virgin flies will be exposed to higher doses of the killing fungus," he said.

Using baits to infect the flies avoids spraying large volumes of spores on the crop, while increasing the dose that the flies are exposed to, he explained.

He added: "The bait with the entomopathogenic fungus has to be very attractive and able to compete with the fruit in the field. But the strategy could work if used in an early stage of the season before ripening of the fruit.

"What kind of bait is attractive enough in the field is still unknown and is part of the follow-up research. In 2017 we plan to move from the cages out to the field."

This research is being carried out in the EU DROPSA project.


Before commenting please read our rules for commenting on articles.

If you see a comment you find offensive, you can flag it as inappropriate. In the top right-hand corner of an individual comment, you will see 'flag as inappropriate'. Clicking this prompts us to review the comment. For further information see our rules for commenting on articles.

comments powered by Disqus

Read These Next

Pest and disease management - Phytophthora root rots

Pest and disease management - Phytophthora root rots

Treatments to defend against these pathogens should be used alongside good hygiene practice.

Pest & Disease Factsheet - Needle blights

Pest & Disease Factsheet - Needle blights

Prevalent in wet, humid conditions and particularly on susceptible crops grown under overhead irrigation, tip blights can adversely affect a range of conifer species.

Pest & Disease Factsheet - Wilt

Pest & Disease Factsheet - Wilt

Poor husbandry, physical damage to roots and various diseases can all cause water deficit in leaves and non-woody stems of plants, leading to loss of turgor pressure in cells and flaccid tissues, which can lead to wilting in bedding, pot plants and nursery stock.