Spotted Wing Drosphila – Drosophila suzukii
Spotted Wing Drosophila – Drosophila suzukii
Description of Insect:
The Spotted Wing Drosophila (Drosophila suzukii) is a small, invasive fruit fly native to Southeast Asia. Unlike typical fruit flies, which typically feed on overripe or decaying fruit, D. suzukii targets healthy, ripening fruit. It is a significant pest in fruit crops, especially soft-skinned berries and grapes.
Adults are about 2-3.5 mm in length, with a characteristic red eye color and dark spots on the wings of males. Female flies are distinguishable by their saw-like ovipositor, which they use to pierce the skin of healthy fruit to lay their eggs. They have yellowish-brown bodies with dark bands on the abdomen.
Their ability to infest fruit before it ripens makes it a particularly troublesome pest in both commercial and home orchards. The damage not only affects fruit quality but also opens the fruit to pathogens, which can lead to further decay. D. suzukii has a rapid reproduction cycle, which increases its potential to cause widespread damage to crops.
Life cycle of Spotted Wing Drosophila:
The Spotted Wing Drosophila follows a typical fruit fly life cycle, consisting of four stages: egg, larva, pupa, and adult. Females lay their eggs on the skin of ripe or nearly ripe fruit, using their saw-like ovipositor to puncture the fruit. A single female can lay up to 200-600 eggs during its lifetime. Once laid, the eggs hatch into larvae, which burrow into the fruit to feed.
The larvae are creamy-white with black mouthparts and can grow up to 6 mm in length. They cause physical damage by feeding inside the fruit, visible as a depressed blemish from the outside. After feeding, the larvae either stays inside, or drops to the ground to pupate in the soil.
The pupal stage lasts 4-5 days, depending on environmental conditions, after which the adult emerges. It can produce 10-13 generations in a single growing season, with peak populations emerging during late summer and fall.
Damage they cause:
The Spotted Wing Drosophila is a major pest of soft fruits, including cherries, strawberries, raspberries, blueberries, and grapes.
- Fruit Damage:Drosophila suzukii causes direct damage to fruit by laying eggs inside the flesh. As the larvae hatch and feed, they create breathing holes in the fruits, making it soft and unsellable. This not only reduces the harvestable yield but also accelerates fruit decay. In some cases, the entry of larvae into fruit makes it susceptible to secondary infections from fungi, bacteria, and molds. This further contributes to crop loss and reduces overall fruit quality.
- Economic Losses:The Spotted Wing Drosophila’s ability to damage fruit before it ripens leads to substantial losses in the commercial fruit industry. Affected crops are often rejected for sale due to the internal damage caused by larvae, rendering the fruit unsuitable for consumption. This pest is particularly problematic for high-value crops like cherries and berries, which are economically significant for growers. In addition to crop losses, growers must invest significant resources into managing the Spotted Wing Drosophila. Pesticide applications and monitoring costs associated with handling damaged fruit and preventing the spread of the pest can add up quickly.