Cold temperature survival of an unwanted pest of kiwifruit

Researchers report in The New Zealand Journal of Crop and Horticultural Science on the survival of White Peach Scale on kiwifruit imported into New Zealand.

Believed to have originated in continental Asia, White Peach Scale (WPS), Pseudaulacaspis pentagona, is an armoured scale insect pest of fruit and ornamental trees. It has a global distribution in major crop producing and exporting countries, excluding New Zealand.

In Italy, WPS has become a serious pest of kiwifruit, infesting all above-ground parts of the plant.

Kiwifruit is imported from Italy to New Zealand in summer each year and live WPS have been found on the imported fruit. With increasing volumes of imported fruit, the risk of establishment of exotic scale insects will increase.

In ‘Measuring the survival of White Peach Scale (Pseudaulacaspis pentagona) on kiwifruit (Actinidia chinensis var. deliciosa ‘Hayward’) in cool storage in Italy’ researchers Kate Stannard, Garry Hill, Alessandra Voscarelli, Riccardo Spinelli and Patrick Connolly report on their study of the survival of WPS on kiwifruit held in cool storage in Italy before being exported to New Zealand.

Stannard, Hill and Spinelli collected kiwifruit from Italian orchards representative of orchards from which New Zealand sources imported kiwifruit. An estimated 25% of the fruit on these orchards were infested with WPS.

WPS has three generations annually on kiwifruit in Italy. The third generation spends the winter as mated females in a quiescent state (hibernation) to survive the cold weather. In spring, the females mature their eggs and give birth to live young (crawlers).

Stannard et al. looked specifically at the survival of this third generation of mated female WPS by storing WPS-infested Actinidia chinesis var. deliciosa ‘Hayward’ kiwifruit in an Italian coolstore. The insect’s ability to survive cool storage and mature and lay eggs when removed from the coolstore were measured. This information was then used to identify risk of WPS survival on fruit arriving in New Zealand from Italy after an expected cool storage duration of 60 – 130 days.

The time required to kill 99% of the adult WPS on the fruit was 203 days, indicating an ability to survive for long periods in cold conditions. Adult female WPS removed from the coolstore after 128 days were able to mature eggs normally and subsequent crawler settlement was observed after 22 days out of coolstore at 20°C.

The researchers were able to conclude that at the peak time of importation of Italian kiwifruit into New Zealand, between December and March, WPS on the fruit will be alive and able to mature eggs and give birth to viable offspring (crawlers).

This research has enabled stakeholders associated with the Italian kiwifruit importation pathway (such as Italian exporters, the New Zealand Ministry of Primary Industries, Kiwifruit Vine Health and New Zealand kiwifruit importers), to be better informed of the risks of the introduction of this unwanted pest on Italian kiwifruit and to develop procedures to mitigate its establishment in New Zealand.

Kate Stannard and Garry Hill are researchers at the New Zealand Institute for Plant and Food Research Ltd.

The research article ‘Measuring the survival of White Peach Scale (Pseudaulacaspis pentagona) on kiwifruit (Actinidia chinensis var. deliciosa ‘Hayward’) in coolstorage in Italy‘ published in The New Zealand Journal of Crop and Horticultural Science is available to read in full at Taylor & Francis.

Source:  Royal Society Te Aparangi

Author: Bob Edlin

Editor of AgScience Magazine and Editor of the AgScience Blog

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