NON CHEMICAL INSECTS/MITES MANAGEMENT ON MANGO PRODUCTION

BY

DENNIS OWUSU BOATENG  (TECHNICAL OFFICER), 
BUNSO COCOA COLLEGE, COCOA HEALTH  & EXTENSION DIVISION
polonium90@yahoo.com
0209092614

Fruit Fly

SPECIES

—  Oriental fruit fly:

◦       The adult Oriental fruit fly is somewhat larger than a housefly, about 8 mm in length. The body color is generally bright-yellow with a dark T-shaped marking on the abdomen.

◦       The wings are transparent. The female has a pointed slender ovipositor use to deposit eggs under the skin of host fruit. Eggs are minute cylinders laid in batches.

—  Medfly:

◦       The adult Medfly is slightly smaller than a common housefly and is very colorful.

◦       It has darkblue eyes, a shiny-black back, and a yellowish abdomen with silvery cross bands.

◦        Its wings, normally drooping, display a blotchy pattern with yellow, brown, and black spots and bands.

◦       This adult Medfly attacks all fruits and it is the most widespread and destructive.

—  Melon fly:

◦       The adult Melon fly is 6-8 mm in length. Distinctive characteristics of the adult are the wing patterns and long third antennal segment.

◦       The back of the thorax is reddish-yellow with light-yellow markings and without black markings.

◦        Its head is yellowish with black spots. Soon after emergence, the Melon fly begins looking for food. The adults are capable of very long flights and can fly as far as 30- 60 km.

◦       The melon fly is rated as one of the world's most serious pests and the most important pest of vegetables especially melons and squashes.

Biology and Life Cycle

—  Eggs of fruits flies are small, white, and slender. These are laid, or inserted into fruit in groups of up to 37 eggs. They hatch within 2-4 days. Larvae are cylindrical, elongate, narrowed, and somewhat curved downward with their mouth hooks at the head.

—  The larvae live and tunnel through the fruit, feed on the pulp, and continue feeding inside the fruit. They jump rather than crawl. When the larvae are ready to pupate, they emerge from the fruit and drop to the ground.

—  Pupae occur in the soil beneath the host plant. The pupal stage lasts for about 10 days. Adult fruit flies are very small insects which lay their eggs in various plant tissues.

—  Wide heads, black or steely green or blue bodies, bright greenish to bluish eyes, and wings that are usually mottled brown or black, characterize the Tephritidae.

—  The Drosophilidae are yellowish and in the wild are largely found around decaying vegetation.

—  The larvae living in fruit feed on the yeasts growing in the fruit.

—  A female adult lays eggs in groups within the fruit and may lay as many as 1,200 eggs in her lifetime.

—  The average life span of the adult is about 30 days. The life cycle of the fruit fly ranges from 12-28 days depending on the climatic condition.

—  In countries with high temperatures, its life cycle is 12 days and longer in areas with cool weather.

Damage

—  Adults and larvae-maggots cause fruit damage. Egg-laying females puncture the fruits leaving scars and holes on the fruit surface.

—   Larval feeding causes premature fruit drop and destroys the pulps of the fruit.

—  The fruit eventually rots making it unsuitable for harvesting and human consumption.

Control measures

1. Cultural practices
• Remove fruits with dimples and oozing clear sap. This method is more effective although laborious than picking rotten fruits from the ground as the maggots may have left the fruits to pupate.
• Harvest crops early when mature green. This is the stage of maturity when crops are not susceptible to fruit fly attack.
• Pick overripe fruits. These are good breeding sites for fruit flies.
• Practice crop and field sanitation. Collect and destroy fallen and damaged ripe fruits. Do not put collected damaged fruits in compost heaps, instead feed to pigs or poultry, or bury to eliminate all sources of possible breeding sites.
2. Bagging the fruits
• To make your own bags, cut old newspapers measuring 15 x 22 cm or 12.5 x 27.5 cm. Double the layers, as single layer breaks apart easily. Fold and sew or staple the sides and bottom of the sheets to make a rectangular bag.
• To bag a fruit, blow in the bag to inflate it. Remove some of the fruits, leaving 1 on each cluster. Insert one fruit per bag then close the bag using coconut midrib or firmly tie top end of bag with string or wire.
• Push the bottom of the bag upwards to prevent fruit from touching the bag. Use a ladder to reach as much fruits as possible.
• Secure the ladder firmly on the ground and for bigger and higher fruits trees, secure or tie the ladder firmly on big branches. Start bagging the mango fruit 55-60 days from flower bloom or when the fruits are about the size of a chicken egg.
• When using plastic bags, open the bottom or cut a few small holes to allow moisture to dry up. Moisture trapped in the plastic bags damage and/or promotes fungal and bacterial growth that caused diseased-fruits.

◦       Plastic also overheats the fruit. Bags made of dried plant leaves are good alternatives to plastic. Remove the bags during harvest and dispose them properly.

3. Trapping with baits

◦       To make your traps, you need 1-liter used plastic bottles. Heat an iron rod to make holes on the neck. Also make a hole on the lid, big enough for the string or wire to pass through.

◦       Insert a string or wire at the lid's hole. Place the bait inside the bottle. Hung traps in a shady part of the tree just above the lower leaves. Replace the bait at least 2 times in a week. Fresh bait is often attractive to the flies.

4. Examples of Fruit fly baits:

◦       Ripe banana peel cut into small pieces and mixed with sugar, flour, and water

◦       Mixture of 1 tsp vanilla essence, 2 tbsp ammonia, ½ cup sugar, and 2 liters of water

◦       Mixture of 1 cup vinegar, 2 cups water, and 1 tbsp of honey.

◦        Mixture of sugar, soya sauce, and ammonia.

Mango Leafhoppers

Biology and life cycle

•       The eggs are laid inside the soft plant tissue on the underside of the leaves.

•       They are elongate or curve, whitish to greenish, and about 0.9 mm long. Eggs hatch in about 10 days. The nymphs look similar to the adults but are very small, pale yellow-green, and wingless.

•       They undergo five nymphal stages. Their cast skins usually remain on the lower surface of the leaf.

•       Nymphs have the ability to walk sideways, forward or backward at rapid paces. Adults are small, elongate, wedge-shaped insects about 3-4 mm long.

•       They hop fast, fly quickly, and can run in all directions when disturbed, hence the name leafhopper.

•       Many leafhoppers look alike but mango leafhoppers are brown in color.

Damage

•       Both the nymphs and the adults feed on the plant sap of the flowers, leaves, tender shoots, and newly formed fruitlets.

•       They then suck out the liquid contents leaving behind the dead and empty cells which are small, white spots.

•       The affected flower heads turn brown and dry up, and fruit setting is affected. Some damage may also occur through egg laying into the leaves and flower stems.

•       Heavy feeding results to ‘hopperburn’ which is caused by the toxic effects of the insects’ saliva.

•       It also causes mosaic virus disease as the pests are carriers of the virus.

•       Leafhoppers produce large amounts of a sugary liquid waste called honeydew. A fungus, called sooty mold, grows on honeydew deposits that accumulate on leaves and branches, turning leaves and branches black.

•       The appearance of a sooty mold on plants is an indication of a leafhopper infestation.

Control measures

—  Use of Plant extracts

◦       Garlic oil spray

◦       Neem oil spray

Preparation and Application

—  Garlic oil spray

◦       Chop finely 100 g of garlic. Soak the chopped garlic in mineral oil for a day. Add ½ liter and 10 ml of soap. Dilute filtrate with 10 liters of water. Constantly shake the container or stir the extract while in the process of the application to prevent oil from separating.

—  Neem oil spray

◦       Add 30 ml of neem oil into 1 liter of soapy water. Constantly shake the container or stir the extract while in the process of application to prevent oil from separating.

Mango Shoot Caterpillar

Biology and life cycle

•       The eggs are lemon-colored and are laid singly on both leaf surfaces on new growths. They hatch in 3 - 5 days.

•       The larva is light to pale-green with purple dots that sometimes has the same color as that of the young tender leaves.

•       The larval development takes about 8 - 10 days.

•       Pupae are dark-brown with no distinguishing lumps or lobes.

•       It is found among the soil debris or near the soil surface. Pupation takes about 16 – 20 days

•       Adult moths are russet-brown with light-brown markings across the forewings and have a wingspan of 25 mm.

•       The forewings are dull-purple with several darker stripes, including a dark-gray purple spot near the apical end while the hindwings are white with a broad smoky-brown or purple-gray margin.

Damage

—  Larvae feed on the growth flushes at the nursery stock, young trees, and top-worked trees.

—  Occasionally, the fruit stalks and young fruits are damaged.

—  The sudden death of a part of a branch, cracked branch, and falling off of a branch are indications of the attack.

Control measures

1. Physical control

–      Prune the affected plant parts and then burn or bury them

2. Use of Plant extracts

–      Ginger,

–      garlic, and

–      chilli extract

Preparation and Application

—  Ginger, garlic, and chilli extract

◦       Soak 50 g of peeled garlic overnight in 10 ml mineral oil. Combine garlic, 25 g of green chilies, and 25 g of ginger. Add 50 ml of water to the mixture. Grind them. Add 3 liters of water.

Mealybugs

Biology and life cycle

•       Eggs are oval, yellow, and are laid in an ovisac of sculpted white wax. Newly hatched nymphs are pale-yellow and have two waxy filaments on the posterior end.

•        As they grow, the white mealy wax coverings on their bodies increase and white lateral processes are formed. Wing pads appear in the prepupal stage and gradually increase in size during the pupal stage.

•       The adults have white mealy wax coverings, hence the name.

Damage

—  yellow. Heavy infestation causes dropping of leaves and flowers and reduces fruit setting. Attacked developing fruits drop prematurely.

—  Like the other sap-feeding insects, mealybugs excrete (eliminate) large quantities of honeydews, which promote sooty mold that caused blackened malformed leaves, stems, and fruits. Infested fruits are unmarketable.

Control measures

1. Physical methods
1. Spray a steady stream of water (reasonably high pressure) on the host plant to knock-off mealybugs. Once on the ground, the fallen ones will be available to ground predators and this will also make their return to the plant difficult. Wetting mealybugs encourages fungal pathogens that may infest on them.
2. Rub or handpick mealybugs from affected plants to reduce populations. They release chemicals that signal others to drop and leave.
3. Prune affected plant parts to remove mealybugs. Remove and destroy heavily infested plant. This will cut down sites and reduce future populations.

2. Plant extracts

–      Soap spray

–      Chilli spray

Preparation and Application

•       Soap spray

–      Mix 2½ tbsp of liquid soap to a gallon of water. Stir well. Another method is to mix 1 tbsp of dishwashing detergent with 1 cup of cooking oil, to make a stock solution. For a gallon of spray, add 5-8 tbsp of stock solution to a gallon of water.

Scales

Biology and life cycle

—  The eggs are covered or found under the mother scales. Eggs hatch into crawlers (nymphs), which are flattened and looking like dusts on the plant surface.

—  Adult females are either oval or round, soft, legless bumps, and are wingless. Males are tiny yellow-winged soft scales. Soft scales secrete honeydews which attract ants.

—  The shells of the soft scales are not left on the plant when lifted up.

—  The soft covering they secrete cannot be separated from the scale's body. Soft scales typically move between branches and leaves during their lifecycle.

Damage

—  Scales remove plant saps by using their sucking mouthparts. Leaves become stunted and turn yellow and the twigs and branches dieback.

—  Some scale species produce honeydews which they secrete while feeding. Honeydews on fruits, leaves, twigs, branches, and barks attract black sooty molds to feed and grow, causing these plant parts to blacken.

Control measures

—  Horticultural oils are concentrated and must be mixed with water. Spray 2% solution against insects and mites. To make a 2% solution, pour 1/3-cup oil into a 1-gallon container, and then fill with water to make a 1-gallon solution. For a 3% solution, start with ½ cup of oil. Apply successive sprays at least 6 weeks apart. You can apply 1% oil solution by mixing 2.5 tbsp of oil in 1 gallon of water.

—  High pressure water jet treatment to dislodge dead scales from trees.

—  It is important to remove the dead scales remaining on the plant because this will ensure protection against newly hatched scales.

—  To dislodge living scales is to use a forceful jet of water to 'power wash' them from barks.