Spotted Wing Drosophila
Overview
Spotted wing drosophila (SWD) is one of the most important pests of soft fruit crops.
Unlike common vinegar flies, SWD attacks ripening fruit before harvest.
It is especially important in:
- strawberries
- raspberries
- blackberries
- blueberries
- cherries
SWD pressure can increase rapidly during warm humid periods close to harvest.
Identification
Adults are small vinegar-fly type insects.
Male SWD: - have dark spots near wing tips
Females: - possess a serrated egg-laying structure - can penetrate ripening fruit
Larvae are: - small white maggots - usually hidden inside fruit
Damage symptoms
Typical symptoms include:
- soft collapsing fruit
- juice leakage
- rapid fruit breakdown
- secondary moulds
- maggots inside fruit
- unmarketable fruit
Damage often increases rapidly near harvest.
Conditions favouring SWD
| Condition | Risk |
|---|---|
| Warm humid weather | Very High |
| Ripening fruit | Very High |
| Unharvested fruit | High |
| Waste fruit | High |
| Dense canopy | Moderate–High |
Monitoring
Use: - SWD traps - fruit inspections - salt testing - harvest inspections
Inspect: - ripening fruit - shaded humid areas - tunnel edges - waste fruit zones
Environmental and hygiene strategy
Good SWD IPM depends heavily on hygiene.
Useful practices: - rapid picking - removal of waste fruit - reducing overripe fruit - improving airflow - avoiding hidden reservoirs
Waste fruit is one of the biggest drivers of population build-up.