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New Zealand Plant Protection 69 (2016): 324

A sweet potato story: the likelihood of porina feeding on kumara

H. Ehau-Taumaunu, S.D.G. Marshall, C.M. Ferguson, M. Mark-Shadbolt, R.M. MacDiarmid and M. O'Callaghan

ABSTRACT

The caterpillar stage of the endemic Wiseana spp. complex, commonly known as porina, are foliage feeders. Research indicates that porina will feed on harakeke (Phormium tenax), red tussock (Chionochloa rubra) and hard tussock (Festuca novae zealandiae). In 1952, Miller reported that porina were abundant in kumara plantations and caused damage to the plants. The accuracy of this observation is uncertain due to taxonomic changes and the ambiguous nature of Miller's identification. Feeding bioassays were undertaken to determine if porina caterpillars would feed on the leaves, stems, or tuber of the Owairaka kumara plant (Ipomoea batatas) using white clover foliage (Trifolium repens) as a control. Over a 6-week Porina provided with tuber had a weight increase of >0.1 g within the first two weeks, which was a 122% gain (compared to clover). The leaves and stems supported less weight gain over the two week period (92% and 85% compared to clover, respectively). These results suggest that porina can feed on kumara plants, but further field testing will be required to support this claim.

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