Posted 6:03 PM by Luigi
Black beetle creates havoc with taro

By Emil Adams (SPC), in Island Business.

Taro is a significant source of income for rural families and a lucrative export for the Pacific. It is also an iconic Pacific food. But a shiny black beetle that burrows into taro corms, leaving unsightly holes that lead to rotting, is a serious threat to crops in affected countries. They include Kiribati, Solomon Islands, Papua New Guinea, New Caledonia, Vanuatu and Fiji.

According to FAO (Food and Agriculture Organisation) reports that in 2000, Papua New Guinea produced around 332,000 tons of taro of which 30% was damaged by taro beetles with losses of A$45.9 million. In Fiji, the taro industry is worth F$10 million annually with 80% of the taro coming from non-infested areas, mainly Taveuni. However, in 2000, one-third of trial taro plots in infested areas of Fiji suffered beetle damage.

Researchers make progress

Concerted efforts by Pacific plant protection specialists to develop a safe and practical control of the beetle have found that two pesticides, Confidor and Bifenthrin, provide the best prospects. The research is being coordinated by the Land Resources Division of the Secretariat of the Pacific Community (SPC) under the Taro Beetle Management Project. The project is funded by the Australian Centre for International Agricultural Research (ACIAR) with the EU providing funds for research in Vanuatu, Solomon Islands and for some activities in Fiji. The University of the South Pacific is also part of the collaboration with the chemistry department carrying out residue analysis and David Hunter of the School of Agriculture providing experimental design and data analysis.

At a project meeting in Suva in December 2005, the Director of LRD, Aleki Sisifa, noted the successes of the past five years. These have resulted in the project being extended by an extra two years after a review by ACIAR.

In the next phase, pesticides will be tested at locations in Fiji, Vanuatu, Solomon Islands and PNG and residues will be analysed. Combinations of pesticides and biocontrol agents will also be trialled. Sisifa emphasises that the project’s main goal is to develop an integrated crop management package for use by farmers. A critical part of the project is to identify the best ways of transferring the technology to them.

Commenting on the research findings, the project coordinator, Sada Lal said, “We’ve been screening pesticides and assessing dosages and application frequencies.

“Since all pesticides are potentially harmful, we need residue analyses to check whether they’re within acceptable limits.”

“We’re also looking at biocontrol methods,” he added. “For example, in PNG, Dr John Moxon found that applying the fungus Metarhizium anisopliae with Confidor gave consistently good control. But the fungus is expensive to produce and farmers in the Pacific don’t have the resources to do it.” In Fiji and Vanuatu, there have been trials of alternative treatments that can be used to prevent the build-up of resistance to pesticides by the beetles. This will be an important part of maintaining a control strategy.

Enlisting public support

Stopping the movement of the taro beetle is still the best method of containing it. In a campaign targeting travellers to the beetle-free island of Taveuni, billboards, brochures, radio and TV spots have been used to spread the message with a recent survey showing that over 90% of growers were aware of the taro beetle and 80% had learned more about it from the media.

Genebank critical back-up

In the past, there have been attempts to take taro planting materials to Taveuni despite a ban by the Fiji Ministry of Agriculture, Sugar and Land Resettlement. The ban also applies to pot plants, soil and manure.

The main taro variety planted for export on Taveuni is Tausala ni Samoa, but some farmers are keen to grow other varieties. To meet this demand and lessen the likelihood that taro material will be smuggled in, the LRD has established a genebank collection of different taro varieties found on the island at the Coconut Research Centre in Taveuni.

New taro varieties available in tissue culture at SPC’s Regional Germplasm Centre will also be taken to Taveuni for testing and adding to the collection (plants in tissue culture are disease-free and provide the only acceptable method of moving germplasm across borders).