The following are the major pests of Mango in mango production:
i) Mango Seed Weevil
Identification:
• The adult is 6 – 9 mm long with grayish brown colour
• Usually active after dusk
• Pretend to be dead when disturbed
• Hide on the bark of mango tree trunks
Damage:
• Feeds on leaves, tender shoots or flower buds
• The beetle lays eggs on young fruit
• Larva burrows into the flesh and destroys the seed/embryo
• No external signs of fruit damage
Control:
• Collect fallen fruits and destroy by burying or burning
• Paint the tree trunk with agricultural lime mixture at flowering to prevent adult weevils from climbing up the tree
• Spray biweekly with Deltamethrin (Decis 2.5EC®). Spray before flowering and during fruit set and repeat every 14 days focused on single fruits
ii) Mango gall midges
Identification:
• The gall midges are small insects measuring about 3 mm in length
Damage:
• Adults lay eggs on young tender leaves
• The larvae mine the leaves producing galls or swelling tissues/pimples
• Dark green, circular galls randomly distributed on the leaf blade
• Under heavy infestations, the leaves wrinkle and remain necrotic and eventually drops
Control:
• Orchard sanitation is important
• Clear weedy areas since adults prefer to stay on these plants
• Prune crowded branches (particularly irregular branches) to allow light penetration
• Conserve natural enemies
• Spray insecticides e.g.) Deltamethrin such as Decis 2.5EC® mixed with mineral oil (mineral oil should Not exceed 2 % i.e. 400 ml in 20 L of water) as soon as new shoots and leaves appear.
iii) Fruit fly
Identification:
• Adult fruit flies are small, about 4 to 7 mm long, dull brownish-yellow to brownish-black with red eyes in some species
• Yellowish flies that are commonly attracted to fermenting fruit of all kinds
• Fruit flies lay eggs under the skin of mature and ripening fruits
• Eggs hatch in 1 – 2 days
• Larvae are about 6 – 7 mm long and can be found in very ripe cull and damaged fruit in the fields
Damage:
• Fruit flies cause direct damage by puncturing the fruit skin to lay eggs
• During egg laying, bacteria from the intestinal flora of the fly are introduced into the fruit.
These bacteria cause rotting of the tissues surrounding the egg.
• The eggs hatch, maggots feed on the fruit flesh making galleries. These provide entry for pathogens and increase the fruit decay
• Fruit dropping to the ground just before the maggots pupate
• Premature ripening of fruits
Control:
• Collect all fallen fruits and destroy by burying at least 50 cm deep or put them in a drum of water with 1 inch oil for 2 weeks.
• Spray with Deltamethrin (DECIS2.5 EC®) etc. The chemicals can be mixed with hydrolyzed protein at a rate of 200 – 1,000 ml/tree or sugar/ molasses and sprayed to act as bait
• Harvest mangoes before they become ripe
• Use of fruit fly trap such as Auto Dissemination Device (ADD) by Real IPM, Hydrolysed protein (CERA TRAP)
• Use of natural enemies, especially parasitic wasps (Diachasmimorpha longicaudata, Fopius arisanus etc.)
• Post-harvest Treatment (Hot Water Dip): Dip fruits for 5 minutes at 500 C water.
iv) Mango scales
Identification:
• Small round reddish brown to white insects
• Usually found in clusters which are immobile
• Insects can be 1 – 7 mm long while the cluster can be 2 cm in diameter
• Clusters found on upper surface of leaves, branches, stem and fruit
• Females are circular in appearance, have dark spot on one side, have neither wings nor legs
• Adult males have two wings
Damage:
• Scales suck the cell sap from the infested areas
• Infested leaves turn pale green to yellow eventually die and drop
• Infested fruits have pink blemishes and drop
• Poor growth and dieback of branches
• Infested young seedlings may die
• Honey dew is produced which form sooty mold, thus reduction of photosynthetic capacity
Control:
• Cut and burn infested tree parts
• Use of natural enemies e.g.) Parasitic Wasps, Ladybird Beetle, Lacewings etc.
• Spray with insecticide mixed with white mineral oils 2%: paraffin oil is sprayed at 3 % water emulsion. Avoid spraying mineral oil during very hot periods of the day
• Use of D-C Tron (Caltex oil) to suffocate the insects.
