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Mealybug

Family of insects (Pseudococcidae)

  • 7 min read
  • 5 chapters

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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 exhibit a radical change during their lifecycle, changing from wingless, ovoid nymphs to 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 plants and secrete a powdery wax layer (hence the name "mealy" bug) used for protection while they suck the plants' juices. The males 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, coffee trees, cassava, ferns, cacti, gardenias, papaya, banana, 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 plants such as Sarracenia (pitcher plants). In such cases, eradicating them is difficult 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 agroecosystems. In India, Withania somnifera plants have been reported as a new reservoir host for an invasive mealybug species Phenacoccus solenopsis.

Some mealybugs of the Hypogeococcus genus 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 ants.

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