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May 2000. In the last few year, Banana bunchy top virus has been found in New Caledonia, and eradication has been attempted. A question was asked about the effectiveness of parasitoids of the vector of BBTV, the banana aphid, Pentalonia nigronervosa.
The parasitoid, Aphidulus colemani, was introduced into Tonga for the control of P. nigronervosa, but with little success. Although 30,000 A. colemani mummies were released, only one was found in the following 4 weeks. The strategy was to focus on taro, often infested with Aphis gossypii, to create a reservoir of the parasitoid which would later attack P. nigronervosa. It did establish on A. gossypii, but there was no evidence, even after 2 years, that it had established on P. nigronervosa. Trials showed that ants prevented predators (lacewing larvae and syrphid flies) populations from building up on banana, and it is likely that ants also interfered with the establishment of the parasitoid.
It would seem that eradication is the best method of control:
- spray the banana with insecticide or kerosene to kill the vectors as soon as symptoms are see
- dig out the whole stool, cut it into pieces, dry and burn or bury it
- did out any regrowth and destroyed in the same way
- K-PINS treated with picloram can be used, but with caution. They leave a residue in the soil and in Samoa replants would not grow if planted in the same hole as the treated plant. If planted to the side they grew normally
- direct injection of gyphosate into stems and suckers (with an injector gun) is an effective method to destroy the plants. But there is still need to destroy the aphids before they have the chance to migrate.
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