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1 October 2000 Development and Mortality of Greedy Scale (Homoptera: Diaspididae) at Constant Temperatures
R. H. Blank, G. S C. Gill, J. M. Kelly
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Developmental times and mortality were determined for four stages of greedy scale Hemiberlesia rapax (Comstock), a key pest of kiwifruit, Actinidia deliciosa (A. Chevalier) C. F. Liang et A. R. Ferguson variety deliciosa, in New Zealand. Scale were reared on potato tubers at seven constant temperatures and developmental stage and mortality were assessed at regular intervals. This required the removal of the scale cover to enable stage and mortality to be accurately determined. High numbers of scale (>1,400) were required at each temperature to sustain a frequent destructive sampling regime. Scale survival to the reproductive stage ranged from 0% at <12.3°C to 45% at 24.6°C. The time for 50% of the live scale population to reach each developmental stage was determined using a Bayesian smoothing program. A linear model of scale development was developed for each stage based on a single, temperature-independent distribution of normalized developmental time. A linear regression of development rate against temperature was used to estimate developmental thresholds that were 9.6, 9.7, 10.3, and 10.6°C and it took 257, 552, 882, and 992 degree-days (DD) to reach the second, third instar, mature, and first reproductive stages, respectively.

R. H. Blank, G. S C. Gill, and J. M. Kelly "Development and Mortality of Greedy Scale (Homoptera: Diaspididae) at Constant Temperatures," Environmental Entomology 29(5), 934-942, (1 October 2000).
Received: 2 November 1999; Accepted: 1 May 2000; Published: 1 October 2000

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