Temperature Requirements for Development of the Obliquebanded Leafroller, Choristoneura rosaceana (Lepidoptera: Tortricidae)

Developmental thresholds and thermal-unit requirements for egg hatching, larval and pupal development, and the period before oviposition were determined for the obliquebanded leafroller, Choristoneura rosaceana (Harris). An average of 111.9 degreedays (thermal units) above 10.0°C was required from oviposition to hatching. Development of the total larval stage required 435.6 degree-days. The developmental thresholds for different larval instars were variable, and significantly different from each other. The fourth larval instar had the lowest developmental threshold, 7.1°C. Other thresholds were: first instar, 11.0°C; second and third instars, 9.9°C; fifth instar, 8.8°C; and sixth instar, 11.4°C. Diapausing third-instar threshold was 11.1°C. Pupae required 117.4 thermal units (above 9.5°C) for adult eclosion. Females required a period before oviposition of 35.2 degree-days above 11.9°C. Egg, larva, pupa, and preoviposition period represented, respectively, 16, 62, 17, and 5% of the total thermal development period from egg to egg.