Mealybug in cotton, papaya and mango: identify and control

Photo at the top: Cotton mealybug females on a stem. Note the white wax and the dark lines on the back, Photo: Zeynel Cebeci, CC BY-SA 3.0

Quick answer

Mealybug in cotton is a small, soft insect covered in white wax that sucks sap from shoots, leaves and bolls. Plants get bunchy, twisted tops, black sooty mould and weak bolls. Remove weed hosts, cut off infested twigs and protect natural enemies. If the threshold is crossed, spot-spray a product labelled for mealybug on your crop.

How to identify mealybug

In Telugu, farmers call it pindi nalli. In Hindi it is usually just called milibug. The word "mealy" means floury: the insect looks as if it has been rolled in flour. Several kinds of mealybug attack crops in India. This guide covers three that matter most to farmers here: the cotton mealybug, the papaya mealybug and the mango mealybug.

Cotton mealybug (Phenacoccus solenopsis)

This is the main mealybug in cotton across India. ICAR's Central Institute for Cotton Research (CICR) found it in about 95% of mealybug samples from cotton fields, including fields around Warangal, Karimnagar and Guntur.

• Adult female: oval, up to about 5 mm long, yellowish green under a thin white wax coat. Look closely for two dark lines running down the back. Short wax threads stick out all around the edge of the body.
• Crawlers (young ones): tiny, yellow and able to walk. This is the stage that spreads from plant to plant.
• Colonies: white, cotton-like clusters on tender shoots, leaf undersides, flower buds, bolls and, in a heavy attack, the main stem.

Papaya mealybug (Paracoccus marginatus)

The adult female is yellow, about 2 mm long, and covered in white wax, with only very short wax threads around the edge. It lays its eggs in a white cottony sac under its body. It covers leaves, stems and fruits of papaya in thick white masses. It also attacks cotton, tapioca, mulberry and vegetables.

Mango mealybug (Drosicha mangiferae)

This is a much bigger insect, sometimes called the giant mealybug. The young ones (nymphs) are pinkish and flat, with a white mealy coat. They crowd onto tender shoots, flower panicles, fruit stalks and young fruits. Unlike the cotton mealybug, it climbs up the tree trunk from the soil every year.

Damage signs

• Shoots become bushy and distorted. Leaves crinkle, twist and bunch together, and young plants stay stunted.
• Sticky honeydew covers leaves and bolls. Black sooty mould grows on it, and badly hit plants look burnt.
• Ants run up and down the plant. They feed on the honeydew and guard the mealybugs from their enemies.
• In a severe cotton attack, bolls fail to open and leaves drop. CICR measured yield losses of about 15% at low infestation and over 50% where the whole plant was covered.
• In mango, leaves and flower panicles dry up and young fruits drop.

Look-alikes and how to tell them apart

• Whitefly nymphs: flat, pale green ovals stuck under the leaf, with no white wax threads. Adults fly up in a cloud when you shake the plant. Mealybugs do not fly. See our whitefly identification and control guide for cotton and vegetables.
• Aphids: soft, pear-shaped, green or black, with no white wax coat. They sit in groups on tender shoots. See the aphid insecticide guide for cotton, chilli and vegetables.
• Mango hopper: wedge-shaped insects that jump or move sideways quickly on mango flowers. See mango hopper: how to identify and control it.
• Powdery mildew on mango flowers: white powder that rubs off, with no insect body or legs under a hand lens. See our powdery mildew guide for mango, chilli and grapes.

Life cycle and when it attacks

Cotton mealybug: a female gives birth to live crawlers, about 340 on average and up to 800, over about a month. Crawlers become adults in about two weeks in warm weather, as CICR recorded. So numbers can climb very fast. Crawlers spread on the wind, in irrigation water, on people's clothes, on farm animals and with ants. Weeds on bunds, roadsides and water channels keep the pest alive between seasons.

CICR notes that mealybugs rarely build colonies on cotton during early and peak vegetative growth. Problems usually start around peak boll formation. The first colonies show up on a few plants in the border rows, next to weeds or a water channel. In Telangana and Andhra Pradesh, watch kharif cotton closely from flowering until the last picking.

Papaya mealybug: it breeds all year where papaya, tapioca and weeds are present. Since 2008 it has spread across south India.

Mango mealybug: it has one generation a year. Females lay eggs in the soil around the tree trunk in summer, and the eggs stay there through the rains. In winter, around December and January, the young nymphs hatch and climb the trunk to reach new shoots and flowers. This is why stopping them at the trunk works so well.

Crops it attacks

Cotton: the cotton mealybug attacks all four cultivated cotton species, Bt and non-Bt. It does the most damage from boll formation onwards. The papaya mealybug and the pink hibiscus mealybug can also be found on cotton.

Papaya: the papaya mealybug covers leaves, stems and fruits. Leaves yellow and drop, plants are stunted, and fruits get sooty mould and lose market value.

Vegetables: CICR recorded severe cotton mealybug attacks on okra (bhindi), tomato, chilli, brinjal and potato, and on cluster bean and green gram. Vegetable fields next to cotton, or with weeds such as congress grass, can carry the pest on to the next cotton crop.

Mango: the mango mealybug attacks shoots, flower panicles and young fruits from December to about April. Flowers dry, and fruit set and fruit retention fall.

When to spray for mealybug in cotton (economic threshold)

The economic threshold is the pest level at which spraying starts to pay for itself. CICR gives this rule for cotton:

• Check at least 40 plants per acre, picked at random. Walk the border rows near weeds and water channels first, because that is where colonies start.
• Give each plant a grade. Grade 1: a few scattered mealybugs. Grade 2: one branch heavily covered. Grade 3: more than one branch or half the plant. Grade 4: the whole plant.
• Start chemical control only if at least 10% of the plants checked are above grade 2.

CICR also advises against spraying young cotton that has only a light infestation, because young plants recover and sprays kill the natural enemies. When you do spray, treat the infested plants and their neighbours as spot sprays. Do not spray the whole field.

For papaya, vegetables and mango we could not confirm a threshold from a recognised public source, so we do not give one here.

Mealybug control without chemicals

• Remove infested twigs gently: cut off twigs covered with mealybugs, drop them straight into a plastic bag, and destroy them far from the field. Shaking or brushing past infested plants spreads the crawlers.
• Keep weeds down: CICR names congress grass (Parthenium), Xanthium, Abutilon, Trianthema and other weeds as hosts. Clear them from bunds, roadsides and water channels during the season and off-season.
• Do not grow a ratoon crop: pull out cotton stalks soon after the last picking. Do not stack old stalks in or near the field, as mealybugs survive on them.
• Use a pigeon pea border: CICR suggests two rows of pigeon pea all around the cotton field, and two rows of pigeon pea after every 6 to 8 rows of cotton, to slow the spread.
• Keep water clean: do not throw infested plants into irrigation channels. Crawlers travel in water.
• Use acid-delinted seed: CICR notes that delinted cotton seed carries no mealybug stages.
• Botanical sprays early on: TNAU lists neem oil 2% and neem seed kernel extract (NSKE) 5%, and CICR suggests neem-based sprays in the early stages of an attack.
• Protect natural enemies: a tiny wasp, Aenasius bambawalei, now keeps cotton mealybug in check in many areas. The ladybird beetle Cryptolaemus montrouzieri, called the mealybug destroyer, eats all stages. Avoid sprays that are not needed so these friends survive.
• Papaya, release parasitoids: the papaya mealybug was brought under control in Tamil Nadu, Karnataka and Maharashtra by releasing a tiny wasp, Acerophagus papayae. ICAR-NBAIR (National Bureau of Agricultural Insect Resources) and TNAU released about 100 wasps per village. NBAIR reports control within about six months. Ask your KVK or state biocontrol laboratory for these wasps, and do not spray chemicals where they have been released.
• Mango, band the trunk: TNAU advises tying a 20 cm wide band of 400 gauge polythene around the trunk in mid-December, about 50 cm above the ground, just below where the branches start. Tie it with jute thread and put a little fruit-tree grease on the lower edge. The young nymphs cannot climb past it. TNAU also advises ploughing out weeds and grasses around the trees in June and July, and releasing Cryptolaemus beetles at 10 per tree.

Chemical control: mealybug insecticide by crop

The product below has cotton and mealybug on its official label. The dose is per acre, converted from the label's per-hectare dose. Use one product at a time. Do not mix products in one tank. Mealybugs hide under wax and in leaf folds, so cover the infested parts well.

Cotton

Product	Contains	Label dose per acre	Water per acre	Wait before harvest
Apache Systemic Insecticide	Fipronil 15% + Flonicamid 15% WDG	162 g	200 L	33 days

Notes from the label: foliar spray soon after the pest appears, from the vegetative to the reproductive stage. Two or three sprays, depending on how bad the attack is. Apache has two active ingredients. It is a ready-mixed product approved on the label, not a tank mix. Follow the CICR threshold and spot-spray advice above, so you spray only where mealybugs are building up.

Mango, papaya and vegetables

None of the products in our store can be suggested for mealybug on mango, papaya or vegetables, so we do not list one here. Use the steps above: the trunk band and Cryptolaemus beetles in mango, and parasitoid release in papaya. Ask your local agriculture officer or Krishi Vigyan Kendra (KVK) for a product that is currently approved for your crop.

Rotate to avoid resistance

Mealybugs that meet the same insecticide group again and again can stop dying from it. Insecticides are grouped by how they work, using the IRAC group number (IRAC is the international Insecticide Resistance Action Committee). Change the group from one spray to the next.

IRAC group	Active ingredient	Product in this article
2B	Fipronil	One part of Apache
29	Flonicamid	One part of Apache

If you spray cotton more than once in a season, do not use Apache back to back. For the next spray, pick a product labelled for cotton mealybug from a different group, and keep to the number of sprays the label allows.

Safety and waiting period

• The waiting period before harvest (PHI, pre-harvest interval) is in the table above. For Apache on cotton it is 33 days from the last spray.
• After an Apache spray, keep people out of the field for 24 hours, as the leaflet says.
• Wear gloves, a mask, goggles and full-sleeve clothes while mixing and spraying. Do not eat, drink or smoke while you work, and wash well afterwards.
• Bees: fipronil is highly toxic to bees. Do not spray when bees are working on cotton flowers, and tell beekeepers nearby before you spray.
• Fish: keep sprays and washings away from ponds, canals and wells.
• Read the label and leaflet before use.

Frequently asked questions

How do I control mealybug in cotton?

Start with clean bunds, no ratoon crop and removal of infested twigs. Check 40 plants per acre. If at least 10% are above grade 2, spot-spray the infested plants and their neighbours with a product labelled for cotton mealybug, such as Apache, at the label dose.

Why does mealybug come back after spraying?

The white wax protects the insect, and colonies hide in leaf folds and boll bracts, so some survive. Eggs and crawlers hatch soon after. Sprays across the whole field also kill the wasps and beetles that keep mealybug down, which can lead to a bigger attack later.

Do ants cause mealybug?

No, but they help it. Ants feed on the honeydew and carry crawlers to new plants. They also chase away the natural enemies. A sudden rise in ants on a plant is a good sign to look for mealybug.

Is there a natural way to control papaya mealybug?

Yes. The parasitic wasp Acerophagus papayae controlled papaya mealybug across south India after 2010. Ask your KVK or state biocontrol laboratory about releases, and avoid chemical sprays where the wasps are active.

When should I band mango trees against mealybug?

In mid-December, before the young nymphs climb up from the soil. TNAU advises a 20 cm polythene band with a little grease on its lower edge, about 50 cm above the ground.

Related reading

• Whitefly insecticide guide: control whitefly in cotton, brinjal, okra
• Aphid insecticide guide: control aphids in cotton, chilli and vegetables
• Jassids in cotton, okra and brinjal: identify and control leafhoppers
• Mango hopper: identify and control it
• Products for cotton
• All insecticides

Sources

• ICAR-Central Institute for Cotton Research (CICR), Nagpur: Compendium of Cotton Mealybugs (2011)
• Tamil Nadu Agricultural University, TNAU Agritech Portal: Cotton mealybug and papaya mealybug
• TNAU Agritech Portal: Giant mealybug of mango
• TNAU Agritech Portal: Biological control of papaya mealybug, a success story
• ICAR-National Bureau of Agricultural Insect Resources (NBAIR): Biocontrol bears fruit: saving papaya from the mealybug
• Insecticide Resistance Action Committee (IRAC): Mode of action classification
• Product label and leaflet of the insecticide listed above.