GUAVA MOTH UPDATE
Guava moth has been on feijoa growers’ radar since its initial discovery in 1997 in the Far North.
Asha Chhagan and Natalie Page, entomologists from Plant & Food Research, Auckland, updated growers on what is known about the pest and priorities for upcoming research.
They said the adult moth is nocturnal so feeds and mates at night. It lays eggs in crevices on a wide host range of fruit, and in the first of several larval stages, the hatching caterpillar burrows into fruit sometimes causing premature fruit to drop. The final larval stage pupates on the ground covered by soil particles after having spun a loose cocoon.
Until 2003, guava moth was largely confined to Northland but since 2014 it has spread further south to Auckland and in 2017 was found in north Waikato and Coromandel. And it isn’t confined to feijoas and guavas having been found on native karaka, persimmons, macadamias, apples, nashi, peaches, plums, apricots grapefruit, lemons, mandarins, oranges, tangelos, loquats and magenta lilly-pilly.
“There is a two component guava moth pheromone lure commercially available for monitoring, and a lot of anecdotal reports regarding control options, but there are currently a lot of gaps in our knowledge,” Asha said.
So a Sustainable Farming Fund (SFF) project was initiated to investigate and provide sustainable management options. Plant & Food has been contracted to NZ Feijoa Growers Association for a three-year research programme running to 2020. Contributions are also coming from the NZ Macadamia Society, Etec Crop Solutions, Hawke's Bay Regional Council, Gisborne District Council and Northland Regional Council. The research will look at distribution, natural enemies, laboratory rearing methods, semi-chemical control and insecticide control options.
Distribution trials have been underway for the last two years in eight regions showed none in the Bay of Plenty, Gisborne, Hawke’s Bay, Taranaki, Manawatu or Nelson.
So far no parasitoid has emerged from eggs, larvae or pupae from over 7000 fruit collected from more than 200 sites in Auckland and Northland. Future research will look at semichemical control options, including mass trapping, lure and kill, and mating disruption. Mass trapping will look at various densities of pheromone traps and the resulting number of male moths caught. Mating disruption will research the efficacy of available twisty ties infused with pheromone from a closely related moth.
Andrew Twidle from Plant & Food in Lincoln will be researching lure and kill possibilities. His PhD work will look at what attracts female guava moth adults to lay on host fruit and whether this can be used to produce a female attractant.
And an insecticide trial will look at five different possibilities to research their efficacy against guava moth with both direct and residual treatments.