Maconellicoccus hirsutus Green Homoptera Pseudococcidae

Natural History

Distribution. This insect is common in the tropical areas of the world, including Africa, Southeast Asia, and northern Australia. It was noted in Hawaii in 1983 and California in 1999. Pink hibiscus mealybug was first reported from the Caribbean region in 1994, where it now infests many islands including Puerto Rico and the Virgin Islands. It seems inevitable that pink hibiscus mealybug will infest Florida, and potentially much of the southern United States north to Virginia and northern California.

Host Plants. As its common name suggests, hibiscus is a favorite host of this mealybug. In fact, many woody ornamental, fruit, and forest trees support high population densities of hibiscus mealybug. Among the important economic hosts are such tropical fruits as avocado, banana, carambola, citrus, custard apple, grape, guava, mango, mulberry, passion fruit, and soursop; and ornamentals such as croton, heliconia, and hibiscus. It is also a minor pest of cotton. Vegetables are infested mostly when the mealybug population density is high, with incidence of infestation declining as overall densities decrease. Among the vegetable hosts most susceptible to infestation are bean, beet, carrot, cowpea, cucumber, okra, pepper, pigeon pea, squash, and tomato, but among the other vegetables occasionally infested are asparagus, cabbage, lettuce, onion, potato, pumpkin, sweet potato, and yam.

Natural Enemies. In Asia and Africa, many predators and parasitoids are reported to attack pink hibiscus mealybug, and some have been introduced to other countries to implement biological suppression

(Mani, 1989). Nevertheless, it remain a pest in Egypt and India (Mani, 1989). The parasitoid Anagyrus kamali Moursi (Hymenoptera: Encyrtidae) was apparently accidentally introduced to Hawaii simultaneously with the mealybug about 1982, and has held this pest in check. When pink hibiscus mealybug attained the Caribbean area in the mid-1990s, considerable damage was caused in Grenada, Trinidad, and elsewhere until Anagyrus kamali could be successfully established. Many parasitoids and predators attacking other mealybugs can attack pink hibiscus mealybug as well.

Life Cycle and Description. In subtropical climates a generation is completed in about 30-40 days and about 10 generations occur annually. Complete development from egg to the adult stage normally occurs in 25-26 days, but it is temperature dependent. In Egypt, reproduction is usually parthenogenetic, but males are sometimes produced, and both sexual and parthenogenetic reproduction occurs in many populations. In the Caribbean region, biparental reproduction apparently occurs exclusively (Williams, 1996). Hibiscus mealybug survives during the cold weather in all stages, but the egg stage is particularly hardy.

This insect is characterized by the presence of waxy white cotton-like secretions, so infested plants have a white fuzzy appearance. If the cottony material is removed, however, the eggs, nymphs, and adults are revealed to be pink.

  1. The female produces a cottony egg sac, which is attached to the host plant. The oval egg sac is about twice as long as wide and consists of loose fibers and eggs internally and matted fibers externally. Each egg sac contains 80-650 eggs, which turn pink before hatching. The oval eggs measure about 0.35 mm long and 0.20 mm wide. Eggs hatch in 3-9 days.
  2. The nymphs are elongate-oval. Initially they are orange but then turn pink. Newly hatched nymphs (crawlers) are mobile, but soon settle and begin feeding. There are three instars in females. Mean duration of the female instars is about 6.7, 6.5, and 7.9 days for instars 1-3, respectively. In males, there are two nymphal stages followed by two "pupal" stages. Mean duration of the male instars is 6.6, 6.5, 1.0, and 5.6 days, respectively. Three pairs of long legs and moderately long six-segmented antennae are evident in nymphs, and the anal region bears a pair of stout hairs. The piercing-sucking mouthparts are narrow and difficult to observe. Occasionally, waxy secretion is found in the posterior region.
  3. In males, the third and fourth instars are nonfeeding stages in which the nymph transforms into a winged adult. The third instar (puparium) is somewhat elongate and resides in a loose mass of fine white filaments. It measures 1.1-1.5 mm long and 0.350.45 mm wide. The fourth instar (pupa) is brownish and shows evidence of wing formation. The antennae are directed posteriorly, and closely resembles the adult, though lacking the terminal abdominal filaments of the adult male. It measures about 1.25 mm long and 0.4mm wide.
  4. The adult female is elongate oval, bears three pairs of relatively small legs, and short but apparent nine-segmented antennae. Occasionally, waxy secretion is found in the posterior region. The female is pink and measures 2.0-3.0 mm long and 0.92.0 mm wide. It bears stout hairs at the posterior end of the body, and is wingless. The adult female may disperse away from the terminal growth of the plant if it is withering and unsuitable for feeding. The pre-ovi-position period varies from 0.5-6 days, followed by an ovipositional period of 4-8 days. Oviposition may occur at the terminal portion of the plant, but during cool weather more sheltered locations are sought for oviposition.

The adult male is slightly smaller than the female in size. The male is pinkish, elongate and narrow in body form. It bears one pair of wings and three pairs of moderately long legs. The antennae are prominent and ten-segmented. The tip of the abdomen bears a pair of long, stout filaments that are white.

A detailed synopsis of pink hibiscus mealybug biology was given by Mani (1989) and Williams (1986, 1996). Ezzat (1958) and Williams (1996) provided a technical description of the species, and the latter author also presented a key to the species of Maconellicoccus.

Image Maconellicoccus Hirsutus Green
Adult female pink hibiscus mealybug.

Damage

These mealybugs may infest any portion of plants, including the below-ground portions. However, the stems and terminal shoot tissues are favored. They secrete a toxic saliva that causes various symptoms in the host plant. Typical symptoms are severe malformation of shoots and leaves, including twisting and crinkling of the foliage. Growth is stunted and tip growth may be bushy rather than elongate. Infested flowers drop and fruit is not produced, or they are small and malformed. In hibiscus, one of the most preferred hosts, galls are produced on terminal growth.

Management

As hibiscus is the preferred host, these plants should be monitored for the presence of pink hibiscus mealybug in an area. If natural enemies are established in an area, particularly Anagyrus kamali, the mealybug should not be a severe pest. In the absence of natural enemies, or if natural enemy activity is disrupted by pesticides, this mealybug can be damaging. Insecticides can provide some control, particularly if systemic insecticides are applied. Application of granular formulations may be necessary for protection of crops with susceptible below-ground product, such as potato. The waxy secretions produced by the mealybugs greatly reduce the effectiveness of contact insecticides. Ants attend pink hibiscus mealybug, so elimination of ants can favor suppression of mealybug by natural enemies. Some natural enemies of pink hibiscus mealybug, including the lady beetle Crypto-laemus montrouzieri Mulsant (Coleoptera: Coccinelli-dae), are available from commercial insectaries and can be released into affected areas to supplement naturally occurring biological control.

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