Blackheaded Fireworm (Lepidoptera: Tortricidae) Larval Phenology Model Based on Diet-Specific Developmental Rates

Abstract

Phenology of blackheaded fireworm larvae, Rhopobota naevana (Hubner), was simulated with developmental rate-summation models. The relationship between temperature and median developmental rates of third instars and pupae were determined by using linear splines. Variation in developmental rates within a population was determined by using Weibull functions. Phenology of summer-generation larvae was simulated in multiple weekly cohorts starting from the estimated times eggs were laid. The model predicted within an average of 1 d (σ = 3.6 d) the date when 50% of the larvae in the field were past the second stadium. Development of larvae in the spring was predicted starting from the time of hatch of sampled eggs. The model included lower developmental rates and higher mortality before new leaves were available. When diet was included in the model, it predicted the date when 50% of the spring-generation larvae was past the second stadium within an average of 2.5 d. The models for the spring and summer generations were sensitive to the estimated dates of egg hatch and oviposition, respectively.