Spotted-wing drosophila (Drosophila suzukii)
Drosophila suzukii
Role in the garden
A small vinegar fly from Asia, spotted in France in 2009-2010 (Montpellier, Corsica, Var), able to lay in healthy ripening fruit thanks to its serrated ovipositor: cherries, raspberries, blackberries, blueberries, strawberries and grapes go soft and leak within days.
Activity period
June to October, as soon as the fruit colours; peak in late summer
How to attract / manage it
Frequent and complete harvests, very fine-mesh nets, vinegar traps for monitoring, destruction of affected fruit.
Practical guide
Where to find them
On ripening red and black fruit, in the garden as in the orchard; the females prefer thin-skinned fruit. Adults of 2 to 3 mm, the males bear a black spot at the tip of each wing.
Prevention
Harvest often and leave nothing ripe or fallen on the ground; cover soft fruit with a net of 1 mm mesh at most from colouring; open up the bushes by pruning; choose early varieties, which ripen before the population peak.
Early signs
Fruit that softens and collapses while it looked healthy, a small puncture visible under a hand lens, oozing juice, white larvae in the flesh after a day or two.
Action / control
Dispose of affected fruit by sealing it (closed bag in the sun, freezing) rather than composting; cider-vinegar traps to follow the populations (they are not enough to protect the crop); net; no treatment available to the home gardener.
Sources
- INRAE, Ephytia : Vigne, Drosophile japonaise (Drosophila suzukii) et Biocontrol, Drosophila suzukii
- EPPO : fiche Drosophila suzukii
- Ctifl : Infos Ctifl, dossiers Drosophila suzukii (2010-2013)
Favourite plants / resources
Related plant entries
Strawberry
A perennial ground cover by runners, a pillar of the low layer in a forest garden. A companion of garlic and onion (documented tradition). To be renewed every 3-4 years from the young rooted runners. A refuge for adult hoverflies.
Raspberry
The shrub layer of a forest garden. Suckering, to be contained by a buried edging. Fruit on second-year canes for non-everbearing types; on the year's shoots for everbearing. A refuge for hoverflies and ladybirds, very nectar-bearing flowers.
Blackcurrant
A perennial shrub for 15 years, with very nectar-bearing flowers in April (visited by bumblebees and bees). A 1.2-1.8 m shrub layer. To be planted in a group of 2-3 plants for good pollination (even self-fertile, a mix of varieties increases production). Prefer the cool partial shade of the north, suffers from drought.
Bilberry (blueberry)
An acid-soil shrub at home in an ericaceous bed, alongside plants that share its needs (strawberry, other Ericaceae), never with lavender or rosemary, which want the opposite. Its fruit set depends on buzz pollination: the bumblebee vibrates the flower to shake the pollen loose where the honeybee struggles, so planting several bushes of different varieties ensures good cross-pollination. A bark or pine-needle mulch keeps the soil cool and moist, as it likes, without raising the pH of its acid soil. Low and spreading, it fills the shrub layer of an open woodland and feeds the early bumblebees of spring.