mango

Pests of Mango

Sirasak Teparkum

Virginia Polytechnic Institute & State University

Mango

Introduction: The mango, Magnifera indica L., is grown throughout the subtropics and tropics and is one of the world's most important fruit crops. India produces 70% of the world's mangoes, although Mexico is the largest exporter of the fresh fruit.

Taxonomy: The mango is a member of the family Anacardiaceae. This family also includes several other important fruit and nut species, e.g. cashew and pistachio nut. The center of greatest species diversity within the genus Magnifera is in Southeast Asia, particularly the island of Borneo. There are at least 62 species within the genus, and 15 of these bear edible fruit. There is considerable debate about the origin of M. indica. Two geographical races are recognized: a polyembryonic race distributed throughout Southeast Asia, including the region of greatest species diversity within the genus, and a monoembryonic race thought to have originated in northeastern India and adjacent Myanmar (Burma) at the northenmost range of the genus. Polyembryonic mango tress are components of the tropical rain forest canopy, whereas monoembryonic mangoes originated in a region with a monsoon climate.

Description: The mango is a perennial, branching, evergreen tree and is 30-40 m tall. Trees flowers after 5-7 years, whereas clonally propagated, grafted trees are generally smaller and can flower after 3-4 years.

· Leaves: Depending on the cultivar, the shapes of mango leaves can range from lanceolate to round oblong. Viewed from the shoot tips, the leaves appear in a whorl. Young leaves are reddish brown but gradually become dark green. The cuticles are thick, and stomata are present in greater numbers on the upper surfaces.

· Flowers: The inflorescence is determinate, and flowers are borne in panicles. They develop usually from terminal buds and occasionally from axillary buds. The mango panicle is conical and consists of a main axis with many branched secondary axes. Both hermaphrodite and male flowers are borne within the same panicle. The number of hermaphrodite flowers in a panicle determines the amount of fruit-set. Although the ratio of hermaphrodite to male flowers appears to be cultivar related, cool temperatures also influence sex expression to favor a preponderance of male flowers. There are normally several hundred flowers in a single panicle, less than 1% of which develop in fruits because of pollination failure and premature fruit drop.

· Fruits: Mangoes are normally harvested when they are physiologically mature but not ripe, which is approximately 4 months after fruit-set. Such fruits require 8-10 days to ripen.

· Seeds: The mango seed is enclosed in a stony endocarp and two thin inner layers, the testa and the tegmen. Mango embryos are large and have massive starch-filled cotyledons. There is no period of developmental arrest of the embryos, and the seed rapidly loses viability in storage. In polyembryonic seeds, the adventitious embryos develop from the epidermal cells of the nucleus, a material tissue that lines the embryo sac. The number of adventitious embryos present in seeds of polyembryonic mango cultivars can range from one to more than 50, although usually fewer than six embryos will develop to maturity and germinate.

Direct pest of mango

Oriental fruit fly ( Dacus dorsalis Hend.)

Host plants: Wide host range, mostly fleshy fruits. In Hawaii, it has been reared from more than 125 different kinds of fruits. Preferred hosts in Hawaii are: guava, mango, citrus, banana, papaya, avocado, peach, coffee, and passion fruit.

Symptoms: Females puncture the skin of fruits with their ovipositor and lay a batch of eggs about 6.0 mm below the surface. Malformation of developing fruits may occur or they may drop prematurely. Sap may ooze from the puncture and attract other insects to feed or oviposit in the wound. Also, various decay organisms may enter and cause discoloration and deterioration of the fruits. After hatching the maggots feed on the fleshy parts and with associated microorganisms cause breakdown of the parts of the fruit affected.

Morphology: The adult is a clear winged fly with a wing span of 5.3-7.3 mm and a body length of 6.0-8.0mm. Viewed from above, the over all color of the abdomen is basically light brown with dark brown transverse bands and the thorax dark brown with conspicuous markings of yellow or occasionally white. The white spindle-shaped eggs are 1.2 mm in length and 0.2 mm in width. The young maggots are white and when fully-grown yellowish and about 10.0 mm in length.

Life cycle: All stages, egg, larva, pupa and adult, occur throughout the year in warm areas. The lowest average temperature at which the immature stages can develop is about 14 0C and temperatures above 21 0C are necessary for the fly to attain sexual maturity without undue prolongation in the preoviposition period. At temperatures between 25-30 0C eggs hatched in 30-36 hr after deposition, most larvae fed for 7 days before becoming fully-grown and leaving the fruits or rearing media. Fully-grown larvae have the habit of curling up and subsequently springing in the air resulting in dispersal for a distance of 30 cm at a time. They entered the soil provided as a pupation media to a depth of 1-5 cm and transformed into puparia within a few hours. Emergence of adult flies occurred 10 days later. Females began laying eggs 5-7 days after emergence. Therefore, the life cycle, egg to egg, was about 25 days but may be considerably prolonged by lower temperatures.

Natural enemies: Several entomophagous arthropods and microorganisms are known to attack the oriental fruit fly. Among arthropods are general predators, such as ants, spiders, staphilinid beetles and earwigs, and a number of larval and puparial parasites.

Control: Prompt disposal of unmarketable fruits from orchards is highly recommended to prevent attraction and reproduction of flies. Bagging of fruits to protect them during development is practiced in many countries. Trapping of flies is also being practiced but there may be little or no control brought about by removal of a small portion of the adult population of an area. In biological control, introduced opiine parasites have been of appreciable value. In Hawaii they changed the status of the fly from that of epidemic conditions to tolerable levels within 2 years.

Mexican fruit fly (Anastrepha ludens, L.W.)

Host plants: A. ludens affects the fruit of Citrus species. Grapefruit is preferred, while lemon and bitter orange are not attacked. The highly polyphagous pest also develops in the fruit of mango, guava, pomegranate, avocado, fig, annona, Spondias sp., peach, pear, apple, quince, Eugenia sp., and of other wild and cultivated plants.

Symptoms: The damage done by the fruit-inhabiting larvae, is like that caused by Ceratitis and Dacus spp. Necrotic lesions form on the peel in places of oviposition, and are often surrounded by a clear zone. Feeding activity destroys the fruit flesh, which is further rotted by bacteria introduced by the female fly on oviposition, leading to premature fruit drop.

Morphology: The Mexican fruit fly is about the size of the common housefly and basically of a yellowish brown color. The thorax is traversed by lighter colored longitudinal striations, with a dark brown spot at the center of the hind portion of the median thoracic segment. Yellowish brown spots and stripes are present on the transparent wings. The stripe on the inside of the rear half of the wing resembles an inverted V, and is not joined with the other stripes on the wing. This feature distinguishes the fly from closely related Anastrepha spp.. The ovipositor of the female is remarkably long, slender and larger than the rest of the abdomen.

Life cycle: The female fly deposits several eggs at a time under the peel with her ovipositor, which is thrust forwards obliquely on oviposition. One female can produce about 800 eggs in the course of her life. The yellowish white larvae feed into the fruit flesh after hatching and remain inside the gradually rotting fruit until ready for pupation. They then bore out into the open and move into the soil, where they pupate in the uppermost layers. The damaged fruit has frequently dropped by that time. The period of development varies with temperature and type of food and takes from about 30-50 days.

Natural enemies: Various Hymenoptera are important parasites. In Mexico, Diachasma (opius) crawfordi is considered to be the main larval parasite. Some predators pursue larvae and pupae in the soil.

Helopeltis bugs (Helopeltis spp.)

Host plants: All Helopeltis spp. are polyphagous living on a range of crop plants plus numerous weeds. The principal crops that act as host plants of the most important species are as follows: Cinchona, cocoa, cotton, cashew, tea, mango, castor, sweet-potato, pigeon pea, guava, and avocado.

Symptoms: Both nymphs and adults feed by pushing their tube-like mouthparts into soft green tissues. Saliva is forced into the plant before feeding begins and is highly toxic to the cells. A dark water-soaked mark first appears around the feeding puncture which later turns into the characteristic lesion with a light brown center and black edge. Stem lesions tend to split longitudinally and finally become corky as callous formation occurs. Young shoots often die off completely and this stimulates secondary branching which is also very susceptible to attack. Fungi often invade lesions on the fruit, causing shrivelling or rotting.

Morphology: Helopeltis are slender bugs about 7-9 mm long and 2 mm wide when full-grown. They have long legs and very long antennae. Colors vary from brown, red and orange through to yellow. The diagnostic feature in both nymphs and adults is the pin-like process which rises vertically from the thorax. It is about 2 mm long in the adult bug.

Life cycle: The eggs are test-tube shaped, slightly curved with a rounded cap and two unequal hair-like filaments at one end. Eggs are white and 1.5-2.0 mm ling. They are inserted singly into soft plant tissues, only the cap and filaments being visible externally. Most eggs are laid in the leaf stalk or main veins. Hatching takes place after 1-4 weeks, according to temperature. The nymphs are slender delicate insects with red and yellow body colors in most species. The full-grown nymph has a body length of about 7 mm, the antennae being much longer. There are 5 nymphal instars, all except the first having a spine-like projection sticking up from the thorax. The total nymphal period takes about 3 weeks in warm weather and up to 6 weeks in the cooler seasons. After the final molt to the winged adult stage, seveal days may elapse before egg-laying begins. Adult females live 6-10 weeks and lay 30-60 eggs 9up to 500 in some species). Breeding is continuous with no evidence of diapuase or other resting stage.

Natural enemies: Parasites and predators may be important in the control of Helopeltis populations on wild hosts. But when a crop is invaded, rates of parasitism are usually very low and only a few general predators, especially spiders, mantids and assasin bugs (Reduviidae) kill significant numbers.

Control: Two crops that are Helopeltis hosts should not be grown next to each other. For example, sweet potatoes or pigeon pea should be grown apart from cotton. Tree crops in the nursery should be grown with minimal shade. Heolopeltis damage is usually worse on crops grown on waterlogged or infertile soils and these should be avoided or ameliorated if possible. Fertilizer application may be benficial on perennial crops.

Indirect Pest of Mango

White wax scale
Mango hopper
Citrus black fly
Bark eating caterpillar
Florida red scale
Black citrus aphid
Cowpea aphid
Striped mealybug
Green scale
Mango shoot caterpillar

White wax scale (Cascardia destructor)

Introduction: White wax scale is a pest of subtropical and temperate climates with relatively high humidity in summer. It is killed by high temperatures in summer. It thrives best on vigorous trees, where it produces the largest individuals and, subsequently, the greatest numbers of eggs.

Host plants: White wax scale has a very wide host range among both native and introduced plants, including ornamentals and weeds. All citrus varieties, grapefruit, guava, persimmon, mango, pear, and quince. Gardenia, lillypilly, pittosporum, and blackthorn, Bursaria spinosum, are also common hosts.

Description: The adult female is enveloped in soft white wax, and may be about 10 mm. long and 7 mm high, although many are only half that size. The chemical composition of the wax has been examined by Hackman (1951). The body of the insect beneath the wax is light red to dark brown, plump and soft. Its hind end narrows into the caudal process that lies flat on the leaf or twig. The Indian white wax scale, Ceroplastes cerifrus, has an elevated caudal process, and the insects's wax coverign has a short down-turned horn at one end.

Life cycle: Egg development occurs during late winter, and egg-laying beneath the body of the insect begins in spring. As the eggs are laid the body shrinks upwards until its ventral surface is close to the dorsal surface, the insect is dead, and all the space beneath it is packed with the oval salmon-colored eggs- up to 3000 in number. The larvae hatch from the eggs, and leave the space beneath the dead parent scale filled with the white remains of the hatched eggs. The larvae are light brown, oval, six-legged and about 0.5 mm long. They make their way towards the outside of the tree and settle, usually on a leaf but sometimes on a young green twig, and commence feeding. Probably, because of their attraction to light, they tend to be on the upper surfaces of the leaves of range, lemon and grapefruit, but on both surfaces of mandarin leaves which are more upright and therefore well lit on both sides. The larvae settle beside the midrib, or if that is crowded, beside a lesser vein. In heavy infestations they settle in two rows - one on each side of the midrib - and there may be as many as 200 larvae per leaf. Within a few hors of steeling the larvae produce white marginal rays of felted material - four at each side, three in front and four at the rear - and a white felted pad on the dorsal surface. They remain on the leaf for four to five weeks, then move to the twigs and settle on permanent positions, usually on new or year-old wood. Feeding starts again and white wax production commences. A conical cap of wax is soon formed and the insect is at the 'peak' stage, which is followed a few weeks later by the 'dome' stage. The wax increases until the scale is fully developed by April. The insect beneath the wax is an adult at the peak stage.

Injury: Direct injury from the feeding seems negligible, but both larvae and adults produce honeydew, which cause problem of black sooty mould fungi on leaves and fruits. The sooty mould can retard color development of the new fruit and interfere with photosynthesis. However, no measurable effects have been observed.

Mango hopper (Idoscopus niveosparsus, Leth.)

Introduction: This hopper species was first recorded from Saharanpur (Uttar Pradesh, India). Subsequently it has been reported from the Philippines, Thailand, Vietnam, Indonesia, Sri Lanka, Burma, Bangladesh, and Pakistan. In India, I. niveosparsus is more destructive in the Southern peninsula than in the North-eastern States.

Host plants: I. niveosparsus is monophagous on mango (Magnifera indica). However, it has been found on Citrus spp. and Calophyllus inophyllum though these do not act as alternate hosts.

Symptoms: Profuse egg-laying within the stallets and florets causes physical injury, resulting in withering of affected parts. In addition nymphs and adults suck the cell sap of inflorescences during spring and of leaves during summer. The removal of inflorescence sap adversely affects fruit setting while on leaves, growth is stunted. The hoppers also exude 'honeydew' which encourgaes the development of the fungi Capnodium mangiferum and Meliola mangiferae, which produce black sooty mold on the dorsal leaf surfaces and branches. This interferes with the photosynthetic activity of the plant, ultimately resulting in failure of the flowers to set and dropping of immature fruits. A severe attack may result in total loss of the crop.

Morphology: The freshly emerged nymph is wedge-shaped and whitish in color with two small red eyes; gradually with each molting the color changes to yellow, yellowish-green, green and finally to greenish-brown. The adult is also wedge-shaped having a greenish-brown body with a pale yellow vertex. The scutellum has three basal black spots, the central one being more or less rectangular. Forewings are thicker than hind wings, bronzy, sub-hyaline, with veins pale yellow and a white line along the costal margin forming a distinct mid-longitudinal line when the insect is at rest. The male is 3.9 to 4.3 mm, while the female is 4.9 to 5.3 mm in length.

Life cycle: Around the end of January or early February, the females make tiny slits with their ovipositor in the tissues of flowering shoots, flower buds or tender leaves in which they lay their eggs singly. A female can lay as many as 200 eggs in her lifetime. The eggs hatch in 4-7 days, the nymphs undergo 4-5 moltings before becoming adults. The nymphal period ranges from 10 to 13 days in South India and 18-20 days in North India. In North India, there are two distinct generations a year; a summer generation during June-August and a spring generation in February-April; the latter being distinctly more destructive since it feeds on the inflorescences. Overwintering takes place in the adult stage when the insects hide in cracks and crevices in the bark of the trees.

Natural enemies: All the tree species of hoppers are parasitised in India by Epipyrops fuliginosa and Pipunculus annulifemer; while in Java, I. niveosparsus is parasitised by Centrodora idioceria. In Bangladesh, two fungal parasites, Aspergillus origer and Fusarium sp. were recorded on adult hoppers.

Citrus black fly (Aleurocanthus woglumi, Ashby)

Introduction: Native from Southeast Asia, it has spread throughout practically all the tropical and parts of the subtropical citrus areas. It is found in Pakistan, Malaysia, Indonesia, Philippines, Thailand, Taiwan, China, Korea, and Africa. It is also found in the United States (Texas and Florida), Mexico, Central America, and South America.

Host plants: Citrus spp.; guava (Psidium guajava); mango (Magnifer indica); Melicoca bijuga; cashew nut (Anacardium occidentale); Annona muricata; Rosa spp. etc.

Symptoms: Nymphs produce copious honeydew, which encourages sooty molds on upper surfaces of leaves, followed by gradual weakening of the tree. The fruit is stained by the 'soot'. Heavy black colonies of the pest occur on the underside of leaves.

Morphology: Adults seldom over 1mm long, aleyrodid type with bluish pubescence on body. They lay eggs on the underside of leaves in a typically spiral pattern. Nymphs sessile, with black straight bristles. Third nymphal instar black with whitish waxy secretions on edge of body.

Life cycle: Populations are more abundant and more widely distributed during the rainy season. Moderately high temperature and relative humidity are favorable for development. Under optimal conditions, duration of life stages are; egg, 8-10 days; first nymph, 8-10 days; second nymph, 9-12 days; third nymph, 10-14 days; pupa, 24-30 days. The whole life cycle can be completed in 60-72 days. There is considerable overlapping of generations, so that all stages may be present throughout the year. However, it si during the rainy season that activity hand damage reach their peak.

Natural enemies: Predators as Scymnus spp. (Coleoptera: Coccinellidae) and Chrysopa sp. (Neuroptera: Chrysopidae) can eliminate tremendous amounts of nymphs. Pathogenic fungi as Aschersonia aleyrodis, are also important biotic mortality factors. Parasites as Prospaltella sp. are very effective in controlling the pest.

Bark eating caterpillar (Indarbela quadrinotata, Wlk.)

Host plants: Mango, citrus, guava, jamun (Syzygium cuminii), loquat, mulberry, pomegranate, a number of forest and ornamental trees, ber (Ziziphus jujuba), drum stick (Moringa oleifera), litchi (Litchi chinensis), rose, etc.

Symptoms: Thick, ribbon like, fine silken webs consisting of wooden particles and excreta are seen hanging on bark and main stems, especially near forks. Below these webs zigzag galleries occur made by the freshly hatched caterpillars and the holes where the caterpillars have bored in. As many as 15-16 holes may be seen on one tree and one caterpillar or pupa occupies each hole. A severe infestation may result in death of the stem but not of the main trunk though there may be interferance with translocation of cell sap resulting in arresting of the growth of the tree and its fruiting capacity being adversely affected.

Morphology: Freshly hatched larvae are dirty brown while the full grown caterpillars (50-60 mm) have pale brown bodies with dark brown heads. Pupae (18´5 mm) are stout, red-dish brown with 2 rows of spines on each abdominal segment arranged transversely on anterior and posterior margins. Adults are pale brown with head and thorax rufous; forewings are pale rufous with numerous dark rufous bands of strigae; abdomen and hind wings are fuscous.

Life cycle: The moths appear in May-June and start laying eggs within 25 hrs of emergence. The eggs are laid in clusters (15-25) under the loose bark of the trees. The egg laying continues throughout the summer. A single female lays as many as 2,000 eggs which hatch in 8-10 days. Freshly hatched larvae nibble the wood and after 2-3 days bore inside the wood. The larval period is 9-11 months. The caterpillars become fully grown by December but continue feeding until March-April. With the rise in temperature they start pupating within the tree trunk or main branches. The pupal period is 3-4 weeks. The adults are short lived; males die soon after mating (within 24 hr or emergence) and the females live for 2-3 days more to lay eggs. There is only one generation per year.

Natural enemies: No parasites and predators have been recorded so far on Indarbela spp. in India. However, in Sri Lanka, Zenillia heterusiae is recorded on I. quadrinotata.

Control: Keeping the orchards clean and avoiding overcrowding of trees help to minimize attacks of the pest. It has been suggested that an iron spike be inserted into the bored hole to kill the caterpillar inside. This is quite effective and may be practiced in small orchards or when the infestation is low.

Florida red scale (Chrysomphalus ficus, Ashm.)

Introduction: Florida red scale was introduced into Florida from Cuba in 1874. It is distributed mainly along the Atlantic coast in Mexico, Central America, South America. But, in California, it's only a pest in greenhouses. It is also found in Europe and along the Mediterranean. This scale insect was a very serious pest of citrus in Florida and Israel. At one time, heavy populations of this scale caused severe defoliation with resulting loss of crops and subsequent yields.

Host plants: More thank 630 plants are listed as hosts. The important tropical crops are annonas, apples, avocados, bananas, various types of berries, cedar trees, citrus, eucalyptus, figs, guavas, mangoes, olives, palms, pears, peppers, pine trees, plums, rubber trees, etc. However, citrus is the most important host plant.

Symptoms: Florida red scale generally causes yellow chlorotic spots when feeding on leaves. When citrus fruits are attacked, yellow spots appear at the feeding sites and the presence of scales on the citrus fruit presents a very unattractive appearance.

Morphology: The scale covering is circular and convex and made up of three rings. The central ring is nearly central, it is light-brown where the second ring is reddish-brown. The third ring is wider than the other two combined and is reddish-brown to black with a thin gray margin. Florida red scale can be differentiated from California red scale by the ease in which the body can be lifted away from the armor, whereas the body of the California red scale remains attached to the armor. Also, Florida red scale lays egg where California red scale gives birth to living young. The body of the California red scale is reddish and kidney-shaped where Florida red scale is bright-yellow colored with the shape of a wide, short top.

Life cycle: The eggs are laid beneath the dorsal scale converingand are oval-shaped lemon-yellow colored with an average of 145 per female. Crawlers (1st instar nymphs) are ovoid-like in shape, bright-yellow colored and very active before permanently settling down. The female goes through two molts before reaching maturity. Males also molt twice with a free flying adult emerging after the last molt. Females must be fertilized before laying eggs. Life cycle from egg to egg takes 78 days at 61 °F while only 28 days are required at 83 °F. In Florida, there are 4-6 generations per year, while 3-4 occur in Israel.

Natural enemies: Florida red scale is parasitized by a wide range of hymenopterous parasites i.e Aphytis holoxanthus. Several species of Coccinellid beetles have been reported feeding upon Florida red scale.

Control: The control of C. ficus in Florida and Israel is depended upon the integration of an effective biological control agent and the occasional use of pesticides when necessary. Pesticides that have been used are azinphos, diazinon, parathion, parathion-oil etc.

Black citrus aphid (Toxoptera aurantii, B.D.F.)

Introduction: Black citrus aphid or Black-orange aphid has been found in the tropical and subtropical regions growing citrus plants around the world i.e. East Asia, Philippines, New Guinea, Mediterranean regions, Africa, Southern parts of the United States, Central America, South America, Hawaii, Australia, New Zealand, etc.

Host plants: Black citrus aphid has a very wide host range, more than 120 host plants have been named i.e. all citrus species, Theobroma cacao, coffee, fig, mangoes, sugar apple, litchee, hibiscus, magnolia, and etc.

Symptoms: Most severe attack by T. aurantii is usually observed in young plantations; young shoots are densely colonized in spring. Leaves colonized by aphids are slightly rolled at the succulent shoot apices and usually curve downwards at the tip. They are not generally rolled as much as with A. spiraecola attack, but can twist on occasion into an open spiral. The black citrus aphid is more rarely found on flowers and flower buds. In severe infestation, the entire new growth on young trees can be destroyed i.e. shoot tip. T. aurantii can transmit Tristeza disease on citrus and is a vector of a citrus mottling virus, blister spot of arabica coffee, and ringspot of excelsa coffee.

Morphology: Virginaptera 1.5-2.0 mm long, brown-black to black, cauda and siphunculi black, abdomen (ventrall) with stridulation pattern and spines typical for Toxoptera spp., also marginal tubercles characteristic for the group, ciliation as in alatae, hairs on pale antennal segment III at most as long diameter of this segment, usually not as long, flagellum of joint VI 1 ¼-1 ½ times as long as joint III, cauda with 10-28 bristles (hairs). Winged morph 1-1.8 mm in length, head, thorax, siphunculi, and cauda black, abdomen dark brown to brown black. T. aurantii produces a scratching noise by vibrant stroking of the posterior part of the body against the legs 9stridulatory movement), which is plainly audible when larger, excited aphid colonies are approached.

Life cycle: In temperate zone, T. aurantii does not usually reach epidemic proportions. If the temperature falls to 15°C, a generation takes almost 3 weeks to develop, whereas it takes no more than 6 days at 25 °C. Development can also be retarded in hot regions, as temperatures approach 30 °C. T. aurantii depends on the young growth and young fruit. As the foliage hardens, the proportion of alatae (winged adult) increases rapidly. These endeavor to reach new young shoots or change to other host plants.

Control: Conventional chemical control, apply preblossom applications of contact or systemic aphicides. Apply foliage applications of systemic compounds in early season or summer. Early applications, when the aphids are fully exposed and before thy curl the leaves, are most effective. Systemic pesticides are required once leaf curling has occurred. Biological control could be effective because T. aurantii has over 70 species of natural enemies (Borner and Heinze, 1957).