TEMPERATURE-DEPENDENT DEVELOPMENT OF EGGS AND LARVAE OF WINTHEMIA-FUMIFERANAE TOTH (DIPTERA, TACHINIDAE), A LARVAL-PUPAL PARASITOID OF THE SPRUCE BUDWORM (LEPIDOPTERA, TORTRICIDAE)

Relationships between temperature and development rates of eggs and larvae of Winthemia fumiferanae Toth. were experimentally determined, using the spruce budworm as host. Hatching of parasitoid eggs was triggered by host pupation. The median time required to complete egg development at different temperatures was estimated from distributions of percentage development success of the parasitoid over time between egg deposition and host pupation. For parasitoid eggs that had sufficient time to hatch, detachment from the host before pupation was the most important cause of mortality at 15°C or higher, but was negligible below this temperature. A curvilinear model describing egg development rate as a function of temperature was used to simulate the development of W. fumiferanae eggs in the field. The relationship between larval development rate and temperature also was modelled, and the variability described. Simulations initiated by host pupation-driven egg hatching, and terminated with prepupal drop to the ground, are presented and discussed with respect to the appropriateness of using host pupation as an indicator of parasitoid egg hatching in the field. © 1990, Entomological Society of Canada. All rights reserved.