The apple leaf-curling midge is a widespread pest of apple orchards. In recent years, the pest has spread across Europe, North America and New Zealand. Infestations stunt the growth of young trees, and can be difficult to detect without effective monitoring and management tools. As part of an IPM programme, monitor adults using Delta traps with Dasineura mali pheromone lures.
Adult: a small mosquito-like fly, approximately 2-3 mm long, dark brown- black in colour. Females possess a reddish abdomen and the males do not.
Eggs: eggs are light pink to orange in colour and elliptical in shape
Larvae: the larvae begin cream to pale-yellow in colour then become orange-red over their development. They are described as small legless maggots reaching 1.5- 2.5 mm in length.
Pupa: the pupa can usually be found within the soil under the damaged trees. The pupa re light-orange in colour inside silk cocoons.
The apple leaf curling midge is capable of producing 3-4 generations per year.
The apple leaf curling midge larvae inflicts damage by feeding on the growing shoots of apple trees. This feeding causes rolling and gall-like thickening of the developing leaves. In some cases, the growing point can be killed. This in turn causes branching or stunting of the terminal shoots. The apple leaf curling midge is more likely to cause significant damage in tree nurseries or in young trees.
Begin monitoring with pheromone traps in early spring at the green cluster growth stage, to give early warning of the infestation and to help with decision-making. The pheromone lure contains the female Dasineura mali sex pheromone, which attracts the males of the species to the trap preventing them from mating with the females. The Dasineura mali lure can be used with the Red Delta Trap.
Russell IPM manufactures and supplies a pheromone lure and traps for the apple leaf curling midge, Dasineura mali. The pheromone trap data will give early warning of the infestation and alert the user to invasion of the midges before population levels build up.
The following notes are general guidelines on implementing pheromone monitoring programmes. Local conditions and practices can vary, so please consult your local advisers for precise advice in your area.
The Dasineura mali pheromone lure lasts for a whole season.
Pheromone lures are a very sensitive tool. They can be affected by exposure to elevated heat and direct sunshine. Wear gloves to handle the lures as direct touching by hand may cause cross contamination leading to mixed catches in the trap. Some contaminants, such as nicotine, may have a repellent effect reducing trap catch.
The lures can be stored for long periods (several years) in a freezer (at about minus 20˚C) if the pack is sealed. Lures can also be stored in a fridge at 4˚C for periods of up to 1 year. Although the pheromone is not harmful to humans, lures should not be kept in a freezer or fridge where food is stored.
The Red Delta Trap with the Dasineura mali pheromone lure is recommended for monitoring this insect.
For monitoring, use two or more traps in each field. Care in choosing the location of deployment of the traps and in interpreting results will be necessary.
Traps should be placed below the tree canopy at 0.5 metres.
Collect data weekly or more frequently if possible. midges captured may be removed on each sampling occasion which makes counting new arrivals easier, but this is not strictly necessary. Decisions on pesticide application should not be taken solely on the trap catch data. Climatic and biological considerations should be taken in account. The threshold of 30 midges per trap per week is proposed for timing sprays of insecticide, depending on your local conditions.
