Reproductive expenditure affects utilization of thoracic and abdominal resources in male Pieris napi butterflies

Abstract

Summary 1.One route to a deeper understanding of the life history of organisms is to identify how resources are acquired and used for reproduction. This may be particularly relevant for insects such as nectar-feeding butterflies, which change diets during the life cycle. 2. Nitrogenous resources used for reproduction in nectar-feeding butterflies come principally from the juvenile diet and are stored in abdominal reserves. Juvenile resources are also used to build the soma of the adult. Consequently somatic and reproductive investment will trade off and constrain the amount of resources available for egg and spermatophore production. Recent findings show a pronounced decrease in thorax resource content and suggest that nitrogen from somatic tissue can be reallocated to reproduction and thus alleviate the resource limitation upon reproduction. 3. In this paper we test the prediction that the observed decrease in thorax nitrogen content is related to the expenditure of resources in spermatophore production in Pieris napi males. By comparing thorax nitrogen content over the life span between males mated 0 -3 times, we show that mating history is an important factor in explaining the observed decrease in nitrogen content. 4. These results support the hypothesis that thoracic resources are used for reproduction in male nectar-feeding butterflies.

Weight Loading and Reproductive Status Affect the Flight Performance of Pieris napi Butterflies

“…P. napi butterflies are known to histolyse thorax muscles in order to make available resources (i.e. nitrogen) that are in limited supply for reproduction (Stjernholm and Karlsson 2006). Although not very likely under the limited time spent in flight and the relatively cool temperature in the experimental arena (Tsuji et al 1986), and considering the fact that the thorax is largely comprised of muscle mass (Hocking 1958) some thorax mass reduction due to water loss cannot be ruled out.…”

Residual reproductive value and male mating success: older males do better

“…Both traits (dry mass and relative fat content) are known to decrease with age in butterflies, presumably as a consequence of resource depletion, and are thus conveniently measurable proxies of male condition (e.g. Karlsson 1994;Stjernholm et al 2005;Stjernholm & Karlsson 2006).…”

Timing of Male Sex Pheromone Biosynthesis in a Butterfly – Different Dynamics under Direct or Diapause Development

“…If a sex pheromone, for example, only can be synthesized from larval derived nutrients and not from adult-derived nectar, the male will be constrained by his larval host plant. Consequently, how organisms use nutritional resources can be fundamental to predictions about life history and evolutionary ecology (e.g., Reznick, 1985;Stearns, 1992) and physiological complexity of resource allocation has received increasing interest (Rose and Bradley, 1998;Zera and Harshman, 2001;Stjernholm and Karlsson, 2006).…”