Number of larval instars and sex-specific plasticity in the development of the small heath butterfly, Coenonympha pamphilus (Lepidoptera: Nymphalidae)

Autor: Enrique GARCÍA-BARROS
Jazyk: angličtina
Rok vydání: 2006
Předmět:
Zdroj: European Journal of Entomology, Vol 103, Iss 1, Pp 47-53 (2006)
Druh dokumentu: article
ISSN: 1210-5759
1802-8829
DOI: 10.14411/eje.2006.007
Popis: The number of larval moults, larval head capsule width and pupal weight were investigated in both direct-developing and diapausing individuals of a South-West European population of Coenonympha pamphilus. The frequency distributions of head widths of successive larval instars overlapped, partly due to variation in the number of larval moults. The larvae that entered diapause went through five instars, instead of the four reported from this species. The evidence indicates that the five instar developmental pathway represents a plastic response rather than an example of compensatory growth. This alternative growth pattern was expressed in response to short photoperiods in parallel with, or as a consequence of, larval diapause. On average, the larvae with five instars had larger heads than their normal siblings. This resulted in comparatively heavier male pupae, while the opposite trend occurred in females. It is concluded that the variation in the number of larval instars is a plastic response to diapause when temperatures remain mild and that it might have an adaptive value in areas with mild winter climates. The sexually dimorphic expression in the larval growth patterns, in terms of pupal weight, may well imply different patterns of allocation of larval resources to adult structures, although sex-dependent differences in investment into purely larval structures cannot be discounted.
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