Biological control of the breadfruit mealybug (Icerya aegyptiaca) in the Pacific

• Department of Resources and Development, Federated States of Micronesia
• Bureau of Natural Resources and Development, Palau
• Ministry of Natural Resources Development, Tuvalu
• Ministry of Environment and Natural Resources Development, Kiribati
• Ministry of Resources and Development, Marshall Islands

Breadfruit (Artocarpus spp.) is a staple food in smaller Pacific nations and one of the few crops that grow well on island atolls. It has nutritional value, and is also a valuable source of timber for boat-building. However, supplies are being jeopardised by the introduced mealybug, Icerya aegyptiaca. Heavy infestations of the pest, which kills young leaves and stems, can reduce fruit yields by 50% and may even kill mature trees.

A first attempt at biological control using the predatory beetle Rodolia reduced mealybug numbers to such an extent that it died out from lack of food. Mealybug populations soon regained pest proportions. Continual reintroduction of the beetle is expensive. Natural enemies such as parasites which can stay in balance with the pest host at much lower densities would be more desirable. Certain insect parasites of I. aegyptiaca, found naturally in India and Pakistan, have shown promise.

Objectives of the project are to:

conduct surveys for, and test, natural enemies of I. aegyptiaca found in Australia (and in Asia if necessary) for suitability for biological control of mealybug in the atoll countries of the Pacific;
introduce, multiply and release an appropriate selection of the biological control agents (free of their own natural enemies or pathogens) in Kiribati and Federated States of Micronesia (FSM); and
establish and conduct an effective monitoring system to determine the success of the biological control.

The biology and habits of the control agents will determine how they are released into the field to produce the best results. After release, the project collaborators will use standard methodology to follow populations of the host and its parasites. They will publish the results of the work at the conclusion of the project.

Collection of possible control agents will continue, particularly in the Northern Territory, where
I. aegyptiaca appears to be under effective natural control. Project scientists at Long Pocket Laboratories will identify the natural enemies collected, with assistance from entomologists of the Australian National Insect Collection and international experts if necessary. I. aegyptiaca will be cultured, and its parasites tested, at Long Pocket Laboratories. Further testing will then be carried out in Kiribati using standard biological control procedures.