Temperaturedependent development of parasitoids on two species of armoured scale insects

Abstract

The duration of development of the parasitoid Encarsia citrina (Craw) (Hymenoptera Aphelinidae) on its hosts greedy scale Hemiberlesia rapax (Comstock) and oleander scale Aspidiotus nerii Bouché (Hemiptera Diaspididae) and of Signiphora merceti (Malenotti) (Hymenoptera Signiphoridae) on greedy scale was determined at five constant temperatures Weibull functions were fitted to the cumulative distribution of parasitoid emergence times and development rates for 5 50 and 95 emergence were calculated Development rates for each parasitoidscale combination were described by the same linear regression equations for 50 emergence and for 95 emergence Developmental threshold and thermal constant for 50 and 95 emergence of parasitoids was 103C and 3638 D and 103C and 4412 D The threshold and thermal constant for 5 emergence varied from 93C to 123C and 2254 D to 3282 D Duration of development in the field was simulated using 13 months of hourly temperatures recorded at Te Puke