Immunocompetence and resource holding potential in the damselfly, Calopteryx virgo L

Abstract

It is generally believed that resource holding potential reliably reflects male quality, but empirical evidence showing this is scarce. Here we show that the outcome of male-male competition may predict male immunocompetence in the territorial damselfly, Calopteryx virgo (Odonata: Calopterygidae). We staged contests between 27 pairs of males and found that winners of the contests showed higher immunocompetence, measured as encapsulation response, compared with that of losers. Furthermore, the winners had larger fat reserves. We also collected 29 males that had not been used in staged contests, and found that in these males encapsulation response correlated positively with an individual's fat reserves. Both immunocompetence and resource holding potential seem to depend on energy reserves, suggesting a trade-off between parasite resistance and energetically costly territorial behavior. The results suggest that the outcome of male-male contest can be used to predict male quality in terms of immune defense.

Evolution and ecology of Calopterygidae (Zygoptera: Odonata): status of knowledge and research perspectives

“…Studies in the same and in closely related species have also suggested that this nonterritorial option is "the best of a bad job" alternative which is adopted when the condition of the animal does not suffi ce to defend a place (Forsyth & Montgomerie 1987). As mentioned before, fat reserves play a role here and those males, which have not accrued enough fat resources, will not be able to defend a place (Marden & Waage 1990, Plaistow & Siva-Jothy 1996, Koskimäki et al 2004). This nonterritorial tactic has been occasionally mentioned to take two additional forms, sneaking and wandering, such as in Mnais pruinosa costalisSelys (Watanabe & Taguchi 1990) and Hetaerina cruentata Rambur (Córdoba-Aguilar 1995).…”

“…However, not all males are able to obtain a territory. Some of the factors known to affect territory acquisition are the following: the amount of muscle mass and fat reserves to be allocated to it (Marden & Waage 1990, Plaistow & Siva-Jothy 1996, Koskimäki et al 2004, and the availability of riverine sites which depends on the number of competing males (Pajunen 1966). It is for the latter reason that in the beginning of the reproductive season is common to fi nd no competition and restricted aggression which become more intense as the season progresses or density increases (Pajunen 1966;Cordero Rivera & Andrés 2002).…”

“…This mutual chasing can be seen as ascending and descending, circular trajectories of variable radii on the territory in dispute and also on those that are close to it (Waage 1973, Córdoba-Aguilar 2000. These encounters stop at times when both males perch on the vegetation but, in general, may take several hours (Waage 1973, Córdoba-Aguilar 2000, Koskimäki et al 2004. These encounters are more likely to result in the resident eviction of the territorial male (e.g.…”

“…Some more experimentation is necessary here to see the role of pigmentation in reliably signaling male condition (as fat) and whether this can be communicated during contests. Related to this, Koskimäki et al (2004) suggested that males may use pigmentation to assess immune ability. However, it does not seem clear why males should need this information for.…”

The role of juvenile hormone in immune function and pheromone production trade-offs: a test of the immunocompetence handicap principle

“…Kö ning & Schmid-Hempel 1995; Rantala et al 2000;Ryder & Siva-Jothy 2000;Siva-Jothy 2000;Rantala et al 2002;Koskimäki et al 2003). Encapsulation is a cellular response through which insects defend themselves against multicellular pathogens such as nematodes and parasitoids (Gillespie et al 1997), but it also plays a role in defence against viruses (Washburn et al 1996).…”