The symptoms appear predominantly on the leaves, but occasionally also on the buds, inflorescences and young fruits of mango trees. The parts infested by this midge become covered with many small, raised galls or blisters. Each wart-like blister or gall is 3-4 mm in size and contains a yellow larva that feeds on tree tissue. In the early stages, the site of egg deposition appears as a small red spot. Heavily-affected leaves may deform, show reduced photosynthesis, and drop prematurely. Infested inflorescences may be unable to open. The small exit holes on the underside of leaves are remnants due to larval presence. These exit lesions may result in secondary fungal infections. Young fruits also display exit holes at the base of the stem. Severely infected mango shoots have almost no inflorescence, which can considerably reduce the yield.
The symptoms are caused by different species of midges, Procontarinia sp. Adult midges are 1-2 mm in size and die within 24 hours of emergence after copulation and egg deposition. Eggs are laid on almost all tree parts, but they are predominantly found on leaves. When they hatch, the larvae penetrate the tissues and inflict damage depending on the organ they affect. Floral parts that are fed upon can consequently dry up and fall to the ground due to extensive feeding. Mature larvae migrate or fall onto the upper soil layers, where they enter the pupal stage. The emergence of adults usually takes place in the afternoon and is favored by cool temperatures (20°C) and 60-82% relative humidity. There can be up to 3-4 pest generations over the period of January to March in the northern hemisphere.
The fall webworm, Tetrastichus sp. parasitizes on the larvae of Procontarinia sp. and hence can be used to control the pest. Other parasitoids are of the family Platygaster sp., Aprostocetus spp., and Systasis dasyneurae. Apply neem seed kernel extract on the tree canopy.
Always consider an integrated approach with preventive measures together with biological treatments, if available. Excessive use of insecticides may cause resistance and kill natural enemies. Spraying of 0.05% fenitrothion, 0.045% dimethoate at bud burst stage of the inflorescence can be effective in controlling the pest. Foliar application of bifenthrin (70ml/100lit) mixed with water has also given satisfactory results. The spraying should be repeated at 7-10 day intervals in the flowering season until the fruits reach pea-size. Sprays containing dimethoate have also been used to reduce Procontarinia sp. populations.