Mealybugs and their biological control in North East India

SM Haldhar / KM Singh / J Konsa / M Nagesh / Ankita Gupta *

Many mealybugs have invaded and established in Indian agro-ecosystem/agro-forestry ecosystems. The key destructors (mealybugs) include Rastrococcusin-vadens Williams (Firake et al., 2015) on mango, Phenacoccussolenopsis Tisley (Hodgson et al., 2008) on cotton, Paracoccus-marginatus Williams and Granara de Willink (Muniappan et al., 2008) on papaya, Phenacoccusma-deirensis Green (Shylesha and Joshi, 2012) on cotton and several other hosts, and Pseudoco-ccusjackbeardsleyi Gimpel and Miller (Mani et al., 2013) on papaya and ornamentals.

1. Mealybug, Rastro-coccusinvadens (Hemiptera: Pseudococcidae)

Originating from the oriental region, the mango mealy bug, Rastroco-ccusinvadens (Hemiptera: Pseudococcidae) is rapidly spreading invasive species; then established in several parts of the world. It is recorded from Pakistan, India, Bangladesh, Sri Lanka, Thailand, Hong Kong, Singapore, Malaysia, Indonesia, Philippines and Vietnam (Williams, 1989). This invasive mealybug, R. invadens was reported for the first time infesting mango (Mangiferaindica) trees from Nagaland, India.

About 37.63% of total mango trees were found to have mild to high infestation of R. invadens in Medziphema and adjoining areas of Nagaland State (Firake et al., 2015) Mealybug, R. invadens and its natural enemies were investigated in India (Narasimham and Chako, 1988) and two promising parasitoids, Gyranusoi-deatebygi Noyes and Anagyrusmangicola Noyes (Hymenoptera: Encyrtidae) were most effective to control this mealybug.

Given the ability of this pest species to spread rapidly in short period of time, necessary action should be taken as soon as symptoms start appearing on mango and other host plants. Certain cultural and mechanical practices were found effective against R. invadens such as spraying with steady stream of water (high pressure) on the host plant to knock-off mealybugs, rubbing or handpicking of mealybugs from affected plants and destruction of affected plant parts etc. Spraying with Azadirachtin @30g ai ha-1 is also suggested to reduce infestation of R. invadens (Ande and Olowojolu, 1999).

2. Mealybug, Phenaco-ccussolenopsis Tinsley (Hemiptera: Pseudo-coccidae)

Since 2005, mealybug of the genus Phenacoccus has been causing serious damage to cotton (Gossypium hirsutum) in north-western India. The outbreaks have been serious on both Bt and non-Bt cotton, and growers have resorted to applying large amounts of pesticides at frequent intervals.

Phenacoccussolenopsis was mainly found on the young growth, including twigs, leaves, flower buds and petioles, but can occur even on the stems in heavy infestations. The infested plants become stunted, and most plants look dehydrated. In severe outbreaks, the balls fail to open and defoliation occurs. In addition, the plants become covered in a dense mat of sooty moulds that grow on the exuded honeydew.

Hodgson et al. (2008) concluded from a comprehensive morphological study that there were no significant differences in specimens from the India subcontinent compared to those from the Neotropics; and thus, considered the name P. gossypiphilous to be a synonym of P. solenopsis. With widespread occurrence of P. solenopsis on cotton and diverse host plants, natural enemies also proliferated in large number in the cotton agro-ecosystem.

One of the important parasitoids Aenasiusari-zonensis played a very significant role in keeping mealybug population under control. The parasitization is dependent upon the density of population. Presence of A. arizonensis was noticed with parasitization ranging from 5-100% across the country with 30%. Other parasitoids also recorded a parasitization ranging from 2-22%.

Inhabitant beetle species such as Cheilomenessexmaculata, Rodoliafunida, Scymnus sp., Nephusregularis, etc. were present in different ecosystems that feed on naturally occurring infestation. These predators and parasitoids have to be conserved and used for effective pest management so that indiscriminate use of insecticides can be avoided.

The predatory beetle, Cryptolaemusmontrouzieri (Mulsant), which is a natural predator of mealybugs in India, was found to feed voraciously on P. solenopsis. This beetle can be released, prior to the cotton season, on weeds and perennial trees where mealybug colonies are found, and during the season on infested cotton plants (Nagrare et al., 2011).

Parasitoid: Aenasiusa-rizonensis (Hymenoptera: Encyrtidae): Female: Length 1.56 — 2.22 mm. Body shiny black; head with large thimble-like setigerous punctures. Antenna with radicle black; scape testaceus yellow, with a brownish patch in middle. Fore wings infuscate in about basal third, the infuscation becoming faint distally, and hyaline in distal half and the costal cell; hind wings hyaline.

Male: Length 1.04-1.45 mm, smaller than female, the sculpture and colour of mesothoracic dorsum, in antennal structure, fore wing venation and genitalia. Head colour and thimble-like punctures about same as in female. Antenna dark brown to black; scape with a white streak from basal third to apex on outer surface (Hayat, 2009).

Predator: Cryptolaemus-montrouzieri is a predator not only on mealybug but on several soft bodied insect pests. Cryptolaemus-montrouzieri was found to feed voraciously on P. solenopsis. The beetle can be released on weeds and perennial trees prior to the cotton season and during the season on infested cotton plants. Both larvae and adult feed on the mealybug crawlers.

The beetle can be multiplied directly on the mealybugs cultured on the sprouted potato similar to mealybug multiplication. Being a voracious predator on the host mealybugs plenty of them need to be added as feed every alternate day onto the rearing container. Both the larval and adult stages of this predator attack all stages of mealybugs.

3. Paracoccusmarginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae)

The infestation of papaya mealybug (PMB) was first noticed in 2007 on papaya, at Coimbatore, Tamil Nadu. By 2009, the pest assumed major pest status across the country and caused huge damage to mulberry, tapioca, Jatropha, cotton and several fruits, flowers and plantation crops in Tamil Nadu causing 90% damage.

The accidental introduction of P.marginatus to Indonesia and India presents a serious economic threat to the agricultural industry in these countries (Muniappan, 2009). Three species of encyrtid parasitoids have been imported by ICAR-NBAIR from USDA (Acerophaguspapayae Noyes &Schauff, Anagy-rusloecki Noyes & Menezes and Pseud-leptoma-stixmexicana Noyes &Schauff) and amongst these A.papayae turned out to be the most promising in India conditions.

Recent observations by ICAR-NBAIR. indicate that P.mexicana has also been established in nature and upto 30% parasitism in reported. Here the brief diagnosis of parasitoids is mentioned.

Parasitoids of papaya mealybug Acerophaguspapayae Noyes and Schauff (Hymenoptera: Encyrtidae)

Female diagnostic characters: A solitaryendoparasitoid of papaya mealybug. It parasitizes the early stage (II instar) nymphs of the mealybug.

Head, including antennae, generally pale orange with fifth funicle segment and base of clava slightly dusky;
mesosoma pale orange; neck of pronotum brown,
posterior margin translucent and side a little paler,
almost yellow;posterior margin of pronotum, mesoscutum and scutellum with conspicuous brown setae;
regulae very pale orange, apically pale greyish brown;
side and ventral side of mesosma and legs slightly paler than dorsal side of thorax;
forewing hyaline except for an inconspicuous, subcircular, infuscate area from stigmalvein to posterior wing margin;
propodeum pale orange, but brown laterally;
metasoma mostly pale orange but brown near cercal plates and
dorsally along posterior margins of tergites III to V (abdominal V to VII) and
indistinctly proximally in middle of tergite VI;
ovipositor sheath pale orange, apically brown (Noyes and Schauff, 2003).

Anagyrusloecki Noyes and Menezes (Hymenoptera: Encyrtidae) Female diagnostic characters: Body robust, slightly flattened dorsoventrally. Head, mesoscutum and scutellum orange; frontovertex with conspicuous white setae and a few dark setae in ocellar area; eyes greenish with minute black setae; metasoma dark brown, ovipositor not prominent.

Antennal formula 1163: scape broad, dark brown to black, externally with a white basal spot and a white subapical band in distal one-third; pedicel brown, distally white, Fl dark brown, rest of antenna white. Forewing with costal cell broad, with two complete lines of setae ventrally, marginal and postmarginal veins combined a little longer than stigma;linea calva interrupted by three rows of setae.

Pseudleptomastixmexicana Noyes and Schauff (Hymenoptera: Encyrtidae)

Female diagnostic characters: Both sexes more or less similar in coloration, dark brown to black with a slight to conspicuous metallic sheen, tegula creamy white to yellowish, abdomen/gaster dark brown with a coppery sheen. Head, mesoscutum and scutellum with reticulate sculpture. Mesosoma with silvery white setae. Forewings hyaline, longer in female with longer posts marginal vein.

4. Phenacoccusmadei-rensis Green (Hemiptera: Pseudo-coccidae)

The invasive Madeira mealybug, Phenacoccus-madeirensis Green got introduced was first reported in India in 2012 (Shylesha and Joshi, 2012). This pest is highly polyphagous and is found infesting numerous host plants.

Some of the common hosts observed include cotton, hibiscus, tomato, potato, brinjal, acalypha, cestrum, etc. Anagyrusamnestos (Encyrtidae), a promising specific parasitoid of the Madeira mealybug has also been documented from India. The mass production of this parasitoid on mealybug reared on potatoes has been standardized at ICAR-NBAIR.

5 .Pseudococcusjack-beardsleyi Gimpel and Miller (Hemiptera: Pseudo-coccidae)

During the survey for monitoring the activity of papaya mealybug, Paraco-ccusmarginatus and its parasitoids in Tamil Nadu, a short-tailed mealybug was recorded to be colonizing with the papaya mealybug in two papaya plantations in June, 2012 (Mani et al., 2012).

The short tailed mealybug was identified as Pseudococcusjackbeardsleyi which is highly polyphagous. Small infestations were detected on papaya fruits from Coimbatore, Tamil Nadu, in 2012. Two species of coccinellids, Scymnus spp. and Cryptolaemus spp. were found to feed on this mealybug.


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