Native to Mexico, the papaya mealybug (Paracoccus marginatus) is controlled in its home range by endemic natural enemies, like the parasitoid Acerophagus papayae. When the papaya mealybug invaded a number of countries in the neotropical region, including the Caribbean, US and parts of South America, encyrtid parasitoids (in particular A. papayae) were introduced to control these pest outbreaks. While these earlier invasions have been managed using biological control methods, the papaya mealybug has still spread to the oriental region, critically damaging papaya crops. In an attempt to restrain the effects of the papaya mealybug studies have been conducted across the region, leading to a recent report that the pest has now spread to Malaysia.
The papaya mealybug is a polyphagous insect pest, hosted by over 60 plant species. These include crops of vital economic importance, such as cotton, coffee, and of course papaya. Papaya mealybugs deposit a waxy layer on the leaf surface reducing the productivity of the plant, and cause new growth to be deformed, leaves to yellow and curl, and fruit to fall early. This can lead to unmarketable produce.
Predators of the mealybug (Apertochrysa and Cryptolaemus) and four species of chalcidoid parasitoids (one identified as A. papayae and the other three likely hyperparasitoids) were also found in Malaysia. Although the A. papayae parasitoids are thought to have invaded with the papaya mealybug, a serious economic threat is still posed to Malaysia’s fruit and ornamental crops, as life history studies of the mealybug show that it is favoured by the warm, humid conditions found there. Advice to farmers is to implement sustainable pest management (ensuring natural enemies are present in high enough numbers) as soon as possible. The report also continues to stress the importance of further study into the papaya mealybug and its control.
Mastoi, M.I.; Nur Azura, A.; Muhammad, R.; Idris, A. B.; Ibrahim, Y. (2011) First Report of Papaya Mealybug Paracoccus marginatus (Hemiptera:Pseudococcidae) from Malaysia. Australian Journal of Basic and Applied Sciences 5 (7), 1247-1250.
For more information on additional biological control methods and the pest itself, see the Plantwise datasheet for papaya mealybug.