Predicting armoured scale insect (Homoptera: Diaspididae) phenology on kiwifruit (Actinidia sp.)

Abstract

Five years of greedy scale (Hemiberlesia rapax) phenology data from a kiwifruit (Actinidia deliciosa ’Hayward') orchard in Whangarei, New Zealand have been used to develop and partially validate a predictive equation for forecasting the timing of seasonal emergence of first generation crawlers using heat unit (day‐degree) summation above a 10°C threshold from 1 August. This was further validated against five armoured scale insect phenology data sets collected from Northland, Coromandel Peninsula, and Bay of Plenty, New Zealand. The armoured scale phenology data were similar at all sites notwithstanding measurements being taken from both ‘Hayward’ and ‘Hort16A’ commercial cultivars and there being large differences in armoured scale insect species composition among sites. The model provided predictions of the 50% crawler emergence date for the first generation of armoured scale within 1 week of observed date at four of the five sites, but was less accurate in predicting the date of 10% and 90% generational emergence. The use of this method as a tool for forecasting insecticide spray applications for the kiwifruit industry is discussed.

Keywords:

• greedy scale
• latania scale
• Hemiberlesia lataniae
• Hemiberlesia rapax
• phenology
• models
• kiwifruit