Seasonal temperatures and the phenology of greedy scale populations (Homoptera: Diaspididae) on kiwifruit vines in New Zealand

Development and Mortality of Greedy Scale (Homoptera: Diaspididae) at Constant Temperatures

“…The developmental thresholds of 7.8ЊC and below obtained by Greaves et al (1994) were in contrast to both this and BerryÕs Þndings that scale did not develop at 9ЊC. Greaves et al (1994) estimated developmental thresholds using the developmental times for each individual stage, rather than an accumulative developmental time from crawler settlement to a particular stage.…”

“…The developmental thresholds obtained for greedy scale stages in this study were closer to those derived from BerryÕs data than those of Greaves et al (1994). Berry (1983) inoculated crawlers onto tubers, which were placed directly into temperature controlled rooms, without holding for 24 h at an optimum temperature for settlement.…”

“…Greaves et al (1994) estimated developmental thresholds using the developmental times for each individual stage, rather than an accumulative developmental time from crawler settlement to a particular stage. However, further analysis of develop- Fig.…”

“…Other estimates were 7.0ЊC (SEM 0.99ЊC) and 9.1ЊC (SEM 0.74ЊC) for developmental thresholds from settlement to second instar and third instar, respectively. In contrast, Greaves et al (1994) estimated the developmental thresholds to be 7.3, 6.7, and 7.8ЊC for the Þrst, second, and third instars of greedy scale, respectively. These estimates, with the exception of the Þrst instar, were signiÞcantly lower than the ones derived from BerryÕs data.…”

Measuring resistance to armoured scale insects in kiwifruit (Actinidia) germplasm

“…During the development of the photographic scale size measurement technique, observations of scale size over time were shown to fit a logistic growth equation, and differences in scale size between genotypes became apparent when the insects were midway through their development and persisted thereafter . Based on known relationships between temperature and development on potatoes under laboratory conditions, for H. rapax (Greaves et al 1994) and H. lataniae (unpublished data), we calculated that at a constant temperature of 218C in the laboratory, H. lataniae and H. rapax should complete their second moult 35 and 39 days, respectively, after settlement and should begin to lay eggs 78 and 81 days after settlement. Thus, the sampling times of 46 and 68 days were known to correspond with a period of significant logistic growth and this was confirmed by the observed change in mean scale cap size between the 46-and 68-day sampling times.…”