Mango gall midge is a major pest of mango and is found in all mango growing countries of the world.
Its feeding induces the formation of small galls, which look like pimples on the leaves.
Serious outbreaks result in defoliation and reduced fruit yield.
The only known host of mango gall midge is mango (Mangifera indica).
The female lays eggs singly into the tissue of young leaves, on the under surface, leaving a small reddish spot.
The eggs hatch within 2-3 days.
Upon hatching, the minute larvae/maggots penetrate the tender parts where the eggs have been laid and start feeding on them.
The mature larvae drop down into the soil for pupation, leaving small holes on the leaves.
If the weather conditions are unfavorable, the mature larvae undergo diapauses in the soil instead of pupating and break diapauses when conditions become favourable.
Larval period varies from 7-10 days while pupal period varies from 5-7 days.
Adults usually emerge from the underside of the leaf leaving the pupal skin protruding from the emergence hole. They are harmless and short lived, dying within 24 hours of emergence after copulation and oviposition.
There are 3-4 overlapping generations of the pest.
Mango leaf gall midge is spread by wind currents and movement of infested plant material.
Adults are small flies, about 1-2mm long, with the males being slightly smaller.
They have a wing length of 1.0-1.5 mm.
Eye facets are circular, but further apart laterally than in other genera and the tarsal claws are toothed.
Both sexes have different antennae size, with males having the longest. The males have distal claspers on its abdomen.
FEEDING & DAMAGE
The midge infests and damages the crop at different growth stages.
The larvae (maggots) bore inside leaf tissue, and feed within, resulting in formation of small raised wart-like galls on the leaves. Gall formation begins within seven days and attains a maximum diameter of about 3-4 mm.
Heavily galled leaves curl up and drop off prematurely, causing dieback of whole branches in susceptible cultivars. The galled leaves remaining on trees are known to provide reservoirs of anthracnose inoculums.
Small emergence holes may be detected where larvae leave the galls through, as they go to the soil for pupation. These holes allow for secondary fungal infections as they create entry points into the plant tissues.
When young fruits are attacked, the exit holes are usually on the lower side of the fruit near its point of attachment to the axis of the inflorescence.
Heavily infested mango trees produce few inflorescences, resulting in reduced yields of mango fruits.
Several methods can be employed in controlling and /or managing mango gall midge. They include the following;
Chemical control method
The following insecticides are recommended for against mango gall midge.
KINGCODE ELITE® 50EC 10ml/20l
LEXUS® 247SC 8ml/20l
PRESENTO® 200SP 5g/20l
LOYALTY® 7OOWDG 5g/20l
EMERALD® 200SL 10ml/20l
EPITOME ELITE® 500SP 10g/20l
PROFILE® 440EC 30ml/20l
Non-chemical control methods
Planting resistant mango varieties
Maintenance of field hygiene/ sanitation
Proper weed control (weeds are alternate hosts of the pests)
Pruning the infested branches
Mixed and intercropping farming reduces the pest population
Ploughing of the orchards exposes pupating and diapausing larvae to sun heat which kills them
Avoid movement of infested plants to new areas
Hand-picking the midges, especially if the population is not dense
Use of sticky traps to catch the flies
It is highly advisable to always mix the insecticide with INTEGRA 3ml/20l whenever spraying. This is a sticker, wetter, spreader and penetrant which greatly improves the efficacy of the chemical
Alternating the insecticides during the crop’s season helps in preventing resistance build up by the pest, which would be if a single chemical was used.
Timely control of the pest is very critical.