Developmental Polymorphism in Choristoneura spp. (Lepidoptera: Tortricidae)

Abstract

C. viridis Freeman, C. occidcntalis Freeman, and C. fumiferana (Clemens), exhibited 6, 7, and 8; 5, 6, and 7; and 6 and 7 larval instars, respectively, when reared on artificial diets. Males exhibited fewer instars than females. Head capsule width data for all 3 species support the developmental polymorphism hypothesis. A change in nutritional quality influenced the proportions of larvae with varying numbers of instars, but did not appreciably influence the kinds of resulting instar groups within a given species.