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CSIRO Division of Entomology

Press Release

Issued 10 March 1995

Australian ladybird beetle to the rescue

An unusual biological control project where an Australian insect was sent overseas to control a tropical pest has been deemed a huge success. The little-known Australian native ladybird beetle, Rodolia limbata, was taken by CSIRO scientists to Micronesia at the end of January last year in the hope that it would control the mealy bug (or fluted scale) which was destroying breadfruit, the islander's main food supply.

"We are very pleased with the result, in just one year the ladybird beetles have knocked out the scale. We expect that breadfruit yields will recover over the next year or two. The locals are delighted!" CSIRO Division of Entomology scientist, Dr Don Sands said.

Dr Sands said that the mealy bug was probably accidentally introduced into the Pacific Islands during the second world war. Experts believe that it originated from somewhere near India. By the 1980's, without its own natural enemies, it had become serious pest of breadfruit and other crops on the Pacific coral islands of Micronesia and Kiribati.

"The scale can weaken or even kill the breadfruit trees, sometimes resulting in total crop losses," Dr Sands said. "This means that the bugs are destroying the island's staple foodstuff. In some areas the problem was so serious that the islanders suffered from malnutrition and food had to be imported, which they could ill-afford".

The soil of the coral atolls is very low on nutrients. This means that few vegetables apart from breadfruit are able to grow in sufficient quantities to feed the people.

An earlier biocontrol attempt, where an Asian ladybird beetle was introduced to Micronesia only achieved temporary control, apparently because it was unable to adapt to the new conditions.

The CSIRO became involved in 1989 after the Micronesian Government approached the Australian Centre for International Agricultural Research (ACIAR) for help. ACIAR funded the project.

Dr Sands said that the fluted scale was a minor pest in the Northern Territory, feeding on decorative and ornamental pests such as the Carpenteria palm. When studying the Northern Territory plants Dr Sands found that of the insects he tested, the Australian ladybird controlled the scale most effectively. He also said that as it could withstand the tropical climate he expected it would be able to survive in the island country.

For further information contact:

Dr Don Sands (07) 214 2803

Rosie Schmedding (06) 246 4194

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