Mealybug

Mealybugs are insects in the family Pseudococcidae, unarmored scale insects found in moist, warm habitats. Of the more than 2000 described species, many are considered pests as they feed on plant juices of greenhouse plants, house plants and subtropical trees and also act as a vector for several plant diseases. Some ants live in symbiotic relationships with them, protecting them from predators and feeding off the honeydew which they excrete.
Description
Mealybugs are sexually dimorphic: females appear as nymphs, exhibiting reduced morphology, and lack wings, although unlike many female scale insects, they often retain legs and can move. Males are smaller, gnat-like and have wings. Since mealybugs (as well as all other Hemiptera) are hemimetabolous insects, they do not undergo complete metamorphosis in the true sense of the word. However, male mealybugs do exhibit a radical change during their life cycle, changing from wingless, ovoid nymphs to wasp-like flying adults.
Mealybug females feed on plant sap, normally in roots or other crevices, and in a few cases the bottoms of stored fruit. They attach themselves to the plant and secrete a powdery wax layer (hence the name "mealy" bug) used for protection while they suck the plant juices. In Asia, mango mealybug is considered a major menace for the mango crop. The males on the other hand are short-lived as they do not feed at all as adults and only live to fertilize the females. Male citrus mealy bugs fly to the females and resemble fluffy gnats.
Some species of mealybug lay their eggs in the same waxy layer used for protection in quantities of 50–100; other species are born directly from the female.
The most serious pests are mealybugs that feed on citrus; other species damage sugarcane, grapes, pineapple (Jahn et al. 2003), coffee trees, cassava, ferns, cacti, gardenias, papaya, mulberry, sunflower and orchids. Mealybugs only tend to be serious pests in the presence of ants because the ants protect them from predators and parasites. Mealybugs are also a vector of viruses in grapevines, spreading grapevine leafroll and grapevine red blotch viruses. Mealybugs also infest some species of carnivorous plant such as Sarracenia (pitcher plants); in such cases it is difficult to eradicate them without repeated applications of insecticide such as diazinon. Small infestations may not inflict significant damage. In larger amounts though, they can induce leaf drop. In recent years, some of the mealybug species have become invasive pests in localities posing a great problem to the new agro-ecosystems. In India, Withania somnifera plant have been reported as a new reservoir host for an invasive mealybug species Phenacoccus solenopsis.
Some mealybugs of the Hypogeococcus are used as biological pest controls of invasive cacti in South Africa, including Harrisia balansae, H. martinii, and Opuntia cespitosa.
Fossil specimens of genus Acropyga ants have been recovered from the Burdigalian stage Dominican amber deposits and several individuals are preserved carrying the extinct mealybug genus Electromyrmococcus. These fossils represent the oldest record of the symbiosis between mealybugs and Acropyga species ants.
Control methods
Pyrethroids such as permethrin, bifenthrin or cyfluthrin can be used to control mealybugs.
Some gardeners use green lacewing (Chrysopidae) larvae to control mealybug infestations, as the larval lacewings are voracious predators of aphids and other small insects.
Metabolism
Mealybugs have a highly sophisticated metabolism that involves not one but two bacterial endosymbionts, one inside the other. The endosymbionts make essential amino acids that the mealybug is not able to acquire directly from its diet. Genetically, mealybugs rely on a "mosaic" of metabolic pathways in which proteins are transported across membranes between what were once independent organisms.
Genera
Acaciacoccus
Acinicoccus
Acrochordonus
Adelosoma
Agastococcus
Albertinia
Allomyrmococcus
Allotrionymus
Amonostherium
Anaparaputo
Anisococcus
Annulococcus
Anthelococcus
Antonina
Antoninella
Antoninoides
Apodastococcus
Artemicoccus
Asaphococcus
Asphodelococcus
Asteliacoccus
Atriplicicoccus
Atrococcus
Australicoccus
Australiputo
Balanococcus
Bessenayla
Bimillenia
Birendracoccus
Boninococcus
Boreococcus
Bouhelia
Brasiliputo
Brevennia
Brevicoccus
Callitricoccus
Calyptococcus
Cannococcus
Capitisetella
Cataenococcus
Chaetococcus
Chaetotrionymus
Chileputo
Chlorococcus
Chnaurococcus
Chorizococcus
Chryseococcus
Cintococcus
Circaputo
Cirnecoccus
Clavicoccus
Coccidohystrix
Coccura
Coleococcus
Colombiacoccus
Conicosoma
Conulicoccus
Coorongia
Cormiococcus
Criniticoccus
Crisicoccus
Crocydococcus
Cryptoripersia
Cucullococcus
Cyperia
Cypericoccus
Cyphonococcus
Dawa
Delococcus
Delottococcus
Densispina
Discococcus
Distichlicoccus
Diversicrus
Drymococcus
Dysmicoccus
Eastia
Ehrhornia
Electromyrmococcus †
Epicoccus
Erimococcus
Eriocorys
Erioides
Erium
Eucalyptococcus
Eumirococcus
Eumyrmococcus
Eupeliococcus
Euripersia
Eurycoccus
Exilipedronia
Farinococcus
Ferrisia
Ferrisicoccus
Fijicoccus
Fonscolombia
Formicococcus
Gallulacoccus
Geococcus
Glycycnyza
Gomezmenoricoccus
Gouxia
Greenoripersia
Grewiacoccus
Hadrococcus
Heliococcus
Heterococcopsis
Heterococcus
Heteroheliococcus
Hippeococcus
Hopefoldia
Humococcus
Hypogeococcus
Iberococcus
Idiococcus
Indococcus
Inopicoccus
Ityococcus
Kenmorea
Kermicus
Kiritshenkella
Lachnodiella
Lachnodiopsis
Lacombia
Laingiococcus
Laminicoccus
Lankacoccus
Lantanacoccus
Lenania
Leptococcus
Leptorhizoecus
Liucoccus
Lomatococcus
Londiania
Longicoccus
Maconellicoccus
Macrocepicoccus
Maculicoccus
Madacanthococcus
Madagasia
Madangiacoccus
Madeurycoccus
Malaicoccus
Malekoccus
Mammicoccus
Marendellea
Mascarenococcus
Maskellococcus
Mauricoccus
Melanococcus
Metadenopsis
Metadenopus
Miconicoccus
Mirococcopsis
Mirococcus
Miscanthicoccus
Misericoccus
Mizococcus
Mollicoccus
Mombasinia
Moystonia
Mutabilicoccus
Nairobia
Natalensia
Neochavesia
Neoclavicoccus
Neoripersia
Neosimmondsia
Neotrionymus
Nesococcus
Nesopedronia
Nesticoccus
Nipaecoccus
Novonilacoccus
Octococcus
Odacoccus
Ohiacoccus
Oracella
Orococcus
Orstomicoccus
Oxyacanthus
Palaucoccus
Palmicultor
Paludicoccus
Pandanicola
Papuacoccus
Paracoccus
Paradiscococcus
Paradoxococcus
Paraferrisia
Paramococcus
Paramonostherium
Paramyrmococcus
Parapaludicoccus
Parapedronia
Paraputo
Pararhodania
Paratrionymus
Parkermicus
Paulianodes
Pedrococcus
Pedronia
Peliococcopsis
Peliococcus
Pelionella
Pellizzaricoccus
Penthococcus
Peridiococcus
Phenacoccus
Phyllococcus
Pilococcus
Planococcoides
Planococcus
Pleistocerarius
Plotococcus
Poecilococcus
Polystomophora
Porisaccus
Porococcus
Prorhizoecus
Prorsococcus
Pseudantonina
Pseudococcus
Pseudorhizoecus
Pseudorhodania
Pseudoripersia
Pseudotrionymus
Puto
Pygmaeococcus
Quadrigallicoccus
Rastrococcus
Renicaula
Rhizoecus
Rhodania
Ripersia
Ritsemia
Rosebankia
Saccharicoccus
Sarococcus
Scaptococcus
Seabrina
Serrolecanium
Seyneria
Spartinacoccus
Sphaerococcus
Spilococcus
Spinococcus
Stachycoccus
Stemmatomerinx
Stipacoccus
Strandanna
Stricklandina
Strombococcus
Synacanthococcus
Syrmococcus
Tangicoccus
Tasmanicoccus
Telocorys
Tibetococcus
Tomentocera
Trabutina
Tridiscus
Trimerococcus
Trionymus
Trochiscococcus
Turbinococcus
Tylococcus
Tympanococcus
Ventrispina
Villosicoccus
Volvicoccus
Vryburgia
Xenococcus
Yudnapinna
References
Further reading
Jahn, G. C. and J. W. Beardsley (1994). "Big-headed ants, Pheidole megacephala: Interference with the biological control of gray pineapple mealybugs". In D.F. Williams [ed.] Exotic Ants: Biology, Impact and Control of Introduced Species. Boulder, Col.: Westview Press, 199–205. .
Jahn, G. C. and J. W. Beardsley (1998). "Presence/absence sampling of mealybugs, ants, and major predators in pineapple". J. Plant Protection in the Tropics 11(1):73–79.
Jahn, Gary C., J. W. Beardsley, and H. González-Hernández (2003). "A review of the association of ants with mealybug wilt disease of pineapple". Proceedings of the Hawaiian Entomological Society. 36:9–28.
External links
NCIPM (National Centre for Integrated Pest Management) – Cotton Mealybugs
Mealy bugs Pseudococcus spp.—BBC gardening advice
CISR – Vine Mealybug—Center for Invasive Species Research summary on Vine Mealybug
On the University of Florida / Institute of Food and Agricultural Sciences Featured Creatures website:
Hypogeococcus pungens
Nipaecoccus nipae, coconut mealybug
Agricultural pest insects
Insect pests of ornamental plants
Insect vectors of plant pathogens