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1 August 2007 Developmental Polymorphism in a Newfoundland Population of the Hemlock Looper, Lambdina fiscellaria (Lepidoptera: Geometridae)
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Abstract
The hemlock looper [Lambdina fiscellaria (Guenée)], a widespread and highly polyphagous Geometridae, is considered one of the most economically important defoliators of North American coniferous forests. Variations in the number of larval instars between geographic populations of this species have been previously reported in the literature. However, whether such developmental polymorphism occurs within a given population is unknown. In this study, we report the presence of both four and five larval instar individuals within a population of hemlock looper in Newfoundland when reared on balsam fir. For both sexes, the majority of individuals reared on balsam fir shoots went through four larval instars, but more than one third of the females (35.3%) went through five larval instars. Females with four larval instars developed faster and had smaller pupal weight than females with five larval instars. However, a growth-related index (weight gain per unit of time) was similar for the two ecotypes (four or five larval instars). No significant difference was observed between the two ecotypes in terms of reproductive capacity (fecundity and egg size). We also found significant differences in life history traits between males and females. Results indicate that developmental polymorphism, in this case, the variation in the number of larval instars, might provide some adaptive attributes that allowed exploitation of a broader ecological niche.
Richard Berthiaume, Éric Bauce, Christian Hébert and Jacques Brodeur "Developmental Polymorphism in a Newfoundland Population of the Hemlock Looper, Lambdina fiscellaria (Lepidoptera: Geometridae)," Environmental Entomology 36(4), (1 August 2007). https://doi.org/10.1603/0046-225X(2007)36[707:DPIANP]2.0.CO;2
Received: 27 November 2006; Accepted: 31 May 2007; Published: 1 August 2007
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