The Pink Hibiscus Mealybug or PHM, is threatening local landscapes and nurseries across Southern Florida. Also known as Maconellicoccus hirsutus, PHM has been found in several locations in Broward and Miami-Dade counties.
It attacks more than 200 kinds of plants, including beans, chrysanthemum, citrus, coconut, coffee, cotton, corn, croton, cucumber, grape, guava, hibiscus, peanuts, pumpkin, rose, and mulberry. Tropical and subtropical fruits: papaya, mango, passion fruit, avocado, citrus, guava, banana, carambola, etc.
Positive identification of the PHM should be done by a professional entomologist. Heavy cotton like, white, waxy buildup on the terminals, stems, and branches of infested host plants may indicate a severe mealybug infestation.
This is a female Citrus mealybug, Planococcus citri (Risso). Notice the medium sized waxy filaments around the body, absence of long tails and the single dark stripe down the center of the body. This species produces an egg mass or ovisac.
This is an adult male citrus mealybug.
The adult female is about 3 mm long and wingless with white, flocculent wax covering the dorsal surface. It has two short, inconspicuous caudal filaments and no lateral wax filaments. The female's body and body fluid are both reddish. The female secretes a white cotton like egg mass, irregular in shape, and lays from 300 to 600 pink eggs inside. First-instar nymphs, or pink crawlers, emerge from the eggs. When the egg mass is teased open, the pink eggs and crawlers are exposed and easily seen. In tropical climates, it takes about 30 days to complete 1 generation.
Smaller than the female mealybugs, adult males are reddish brown and have one pair of wings and two long wax caudal filaments. The males have nonfunctional mouthparts. Males do not feed and live for only a few days. Unmated females produce a sex pheromone (an attractant scent) that lures PHM males for mating.
The PHM extracts juices from its host plant and leaves a toxic saliva as it feeds. This process produces malformation of fruit, curly and contortion of leaves, as well as stunted leaves and terminal growth, which is commonly called "bunchy top". This can also kill the host plant.
This is an nasty PHM infestation on a hibiscus.
The PHM may be spread naturally by wind, birds, and other wildlife, or by people moving infested plant material to non-infested areas.
Insecticides and pesticides have little effect on mealybugs. Their waxy bodies help protect from these methods of control.
The most effective way to control mealybugs is to introduce its natural predators. The USDA's Offshore Biological Control Initiative has run several successful studies with parasitic wasps (Anagyrus kamali and Gryranusoidea indica) in the Caribbean in the last 10 years and has seen a 60%-80% reduction of PHM within six months of their release. Also, Florida's natural population of predaceous lady beetles such as Cryptolaemus montrouzieri have been observed eating the PHM.
Parasites are considered the long-term solution to this mealybug infestation. The parasites are self-perpetuating: once released into an area and established, they persist even when the mealybug is at low population densities, and they continue to attack the mealybug, keeping populations below economic injury levels.
Mild infestations of Comstock, Longtailed and Citrus Mealybugs have been know to be eradicated with mild soapy insecticide HOWEVER; it is best treated by a professional. Any attempt to control mealybugs with this method can kill predacious or predatory bugs, thus eliminating the beneficial bugs.
Your best options are to contact your local county extension office or contact the nearest office of USDA's Animal and Plant Health Inspection Service, Plant Protection and Quarantine unit or your State department of agriculture. Let them handle it. They are more than willing. Don't hesitate to call because the economic losses to crops can be outrageous.
References include the Broward County Extension, University of Georgia College of Agricultural and Environmental Sciences - Dept. of Entomology and the United States Department of Agriculture
Animal and Plant Health Inspection Service.