Thermal Requirements for Preimaginal Development of the Strawberry Leafroller (Lepidoptera: Tortricidae)

Abstract

Preimaginal development rates (egg, larval, pupal, and egg to adult) for the strawberry leafroller, Ancylis comptana (Froelich), were determined at six constant temperatures: 14, 18, 22, 26, 30, and 34°C (±2°, 16:8 [L:D]). Total development was fastest at 30° (22.3 ± 0.2 d) and 26°C (28.1 ± 0.3 d); 108.5 ± 9.6 d were required for total development at 14°C. Survival was >75% between 18 and 30°C, but decreased to 31% at 14 and 34°C. Based on a linear model of the temperature–developmental rate relationship, K and t values were 78 DD (degree-days) above 10.3° for eggs, 254 DD above 9.7° for larvae, 100 DD above 10.9° for pupae, and 431 DD above 10.2°C for total preimaginal development. A four-parameter biophysical model of the temperature–development relationship indicated that high temperature inhibition occurred from 29 to 33°C for the preimaginallife stages. Field development of second- and third-generation egg and larval stages was predicted within three calendar days. Management of the strawberry leafroller is greatly facilitated by predicting egg hatch to synchronize control measures with the first instars, which do not exhibit leaf-rolling behavior.