Limits...
The best timing of mate search in Armadillidium vulgare (Isopoda, Oniscidea).

Beauché F, Richard FJ - PLoS ONE (2013)

Bottom Line: We found that the attractiveness of individuals was mediated by short-distance chemical cues and tested individuals were able to discriminate and prefer individuals of the opposite sex.Moreover, male preference to female increased during their moulting status as they matured.Males were particularly more attracted by females with appearing white calcium plates, which corresponds to the beginning of their higher receptivity period.

View Article: PubMed Central - PubMed

Affiliation: Université de Poitiers, Laboratoire Ecologie et Biologie des Interactions, UMR CNRS 7267, Equipe Ecologie Evolution Symbiose, Poitiers, France. Freddie.jeanne.richard@univ-poitiers.fr

ABSTRACT
Mate choice is mediated by many components with the criteria varying across the animal kingdom. Chemical cues used for mate attractiveness can also reflect mate quality. Regarding the gregarious species Armadillidium vulgare (isopod crustacean), we tested whether individuals can discriminate conspecifics at two different levels (between sex and physiological status) based on olfactory perception. Tested conspecifics were individuals of the same or opposite sex, with the females at different moult stages. We found that the attractiveness of individuals was mediated by short-distance chemical cues and tested individuals were able to discriminate and prefer individuals of the opposite sex. Moreover, male preference to female increased during their moulting status as they matured. Males were particularly more attracted by females with appearing white calcium plates, which corresponds to the beginning of their higher receptivity period. These differences in attractiveness due to sex and physiological status are likely to shape the composition of aggregates and facilitate mate finding and optimize the reproductive success for both males and females. Thus aggregation pheromones could be linked to sex pheromones in terrestrial isopods.

Show MeSH

Related in: MedlinePlus

Variation of female attractiveness to males throughout a female intermoult preceding a parturial moult.(o: oocytes (small white: before vitellogenesis, medium light grey: first stage of vitellogenesis, big dark grey: second stage of vitellogenesis); A/B: post-ecdysis, C: di-ecdysis, D0, D1, D2–4: beginning, middle and end of pre-ecdysis, E: ecdysis; triangle: appearance and development of white calcium plates; the evolution of attractiveness during di-ecdysis is approximated according to the difference that was observed between attractiveness of post-ecdysis and pre-ecdysis females). The hemolymph ecdysteroid titers curve is adapted from Chang and Mykles [37]. The female attractiveness to males curve is based on the current results (plain lines) and unknown attractiveness evolution (dots).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3585876&req=5

pone-0057737-g007: Variation of female attractiveness to males throughout a female intermoult preceding a parturial moult.(o: oocytes (small white: before vitellogenesis, medium light grey: first stage of vitellogenesis, big dark grey: second stage of vitellogenesis); A/B: post-ecdysis, C: di-ecdysis, D0, D1, D2–4: beginning, middle and end of pre-ecdysis, E: ecdysis; triangle: appearance and development of white calcium plates; the evolution of attractiveness during di-ecdysis is approximated according to the difference that was observed between attractiveness of post-ecdysis and pre-ecdysis females). The hemolymph ecdysteroid titers curve is adapted from Chang and Mykles [37]. The female attractiveness to males curve is based on the current results (plain lines) and unknown attractiveness evolution (dots).

Mentions: On the other hand, aggregation might also increase male-male competition. Indeed, in A. vulgare, female receptivity is limited to a very short period while males are sexually active all year round except when moulting [44]. In aquatic species, pre-copulatory mate-guarding is a strategy by which males can monopolize a female mate [63], [64]. However, in terrestrial isopods such as A. vulgare, this strategy is not observed. Several explanations have been proposed for this difference including higher costs of mate-guarding in terrestrial compared to aquatic environment, male-induced female resistance and capacity of sperm storage by females in terrestrial species [63], [65]. Indeed, sperm can be stored for 12 months by females A. vulgare and be used to fertilize another clutch [45], [66], [67]. Even if the female remates with a second male, at least 50% of the brood will be sired by the first male due to stored sperm precedence. In A. vulgare, mating induces an immediate refractory period during which females reject male mating attempts [66]. All these parameters make it very beneficial for a male to locate receptive females before any other male. This is congruent with the hypothesis of Lefebvre et al.[68] about antennal sexual dimorphism being a consequence of male scramble competition. Here we show that males can locate receptive females, using short-distance chemical cues. Indeed, we found that females starting the second stage of vitellogenesis (start of pre-ecdysis or D1) were the most attractive, which matches their period of higher receptivity (Figure 7). On the other hand, females at the end of pre-ecdysis (D2–4) were less attractive than other females and they were not particularly more attracted to males than to other females. Eggs are fertilized when laid in the marsupium after the parturial moult, by passing through the oviduct where the sperm is stored [67]. Males could be less attracted to females at this stage because they are more likely to have already mated and stored sperm. These females might as well not be receptive anymore and resist mating attempts because of the refractory period. Moreover, moulting individuals are likely to be more vulnerable (predation, infection) and might not be so attracted by conspecifics compared to the rest of the time when they are gregarious.


The best timing of mate search in Armadillidium vulgare (Isopoda, Oniscidea).

Beauché F, Richard FJ - PLoS ONE (2013)

Variation of female attractiveness to males throughout a female intermoult preceding a parturial moult.(o: oocytes (small white: before vitellogenesis, medium light grey: first stage of vitellogenesis, big dark grey: second stage of vitellogenesis); A/B: post-ecdysis, C: di-ecdysis, D0, D1, D2–4: beginning, middle and end of pre-ecdysis, E: ecdysis; triangle: appearance and development of white calcium plates; the evolution of attractiveness during di-ecdysis is approximated according to the difference that was observed between attractiveness of post-ecdysis and pre-ecdysis females). The hemolymph ecdysteroid titers curve is adapted from Chang and Mykles [37]. The female attractiveness to males curve is based on the current results (plain lines) and unknown attractiveness evolution (dots).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585876&req=5

pone-0057737-g007: Variation of female attractiveness to males throughout a female intermoult preceding a parturial moult.(o: oocytes (small white: before vitellogenesis, medium light grey: first stage of vitellogenesis, big dark grey: second stage of vitellogenesis); A/B: post-ecdysis, C: di-ecdysis, D0, D1, D2–4: beginning, middle and end of pre-ecdysis, E: ecdysis; triangle: appearance and development of white calcium plates; the evolution of attractiveness during di-ecdysis is approximated according to the difference that was observed between attractiveness of post-ecdysis and pre-ecdysis females). The hemolymph ecdysteroid titers curve is adapted from Chang and Mykles [37]. The female attractiveness to males curve is based on the current results (plain lines) and unknown attractiveness evolution (dots).
Mentions: On the other hand, aggregation might also increase male-male competition. Indeed, in A. vulgare, female receptivity is limited to a very short period while males are sexually active all year round except when moulting [44]. In aquatic species, pre-copulatory mate-guarding is a strategy by which males can monopolize a female mate [63], [64]. However, in terrestrial isopods such as A. vulgare, this strategy is not observed. Several explanations have been proposed for this difference including higher costs of mate-guarding in terrestrial compared to aquatic environment, male-induced female resistance and capacity of sperm storage by females in terrestrial species [63], [65]. Indeed, sperm can be stored for 12 months by females A. vulgare and be used to fertilize another clutch [45], [66], [67]. Even if the female remates with a second male, at least 50% of the brood will be sired by the first male due to stored sperm precedence. In A. vulgare, mating induces an immediate refractory period during which females reject male mating attempts [66]. All these parameters make it very beneficial for a male to locate receptive females before any other male. This is congruent with the hypothesis of Lefebvre et al.[68] about antennal sexual dimorphism being a consequence of male scramble competition. Here we show that males can locate receptive females, using short-distance chemical cues. Indeed, we found that females starting the second stage of vitellogenesis (start of pre-ecdysis or D1) were the most attractive, which matches their period of higher receptivity (Figure 7). On the other hand, females at the end of pre-ecdysis (D2–4) were less attractive than other females and they were not particularly more attracted to males than to other females. Eggs are fertilized when laid in the marsupium after the parturial moult, by passing through the oviduct where the sperm is stored [67]. Males could be less attracted to females at this stage because they are more likely to have already mated and stored sperm. These females might as well not be receptive anymore and resist mating attempts because of the refractory period. Moreover, moulting individuals are likely to be more vulnerable (predation, infection) and might not be so attracted by conspecifics compared to the rest of the time when they are gregarious.

Bottom Line: We found that the attractiveness of individuals was mediated by short-distance chemical cues and tested individuals were able to discriminate and prefer individuals of the opposite sex.Moreover, male preference to female increased during their moulting status as they matured.Males were particularly more attracted by females with appearing white calcium plates, which corresponds to the beginning of their higher receptivity period.

View Article: PubMed Central - PubMed

Affiliation: Université de Poitiers, Laboratoire Ecologie et Biologie des Interactions, UMR CNRS 7267, Equipe Ecologie Evolution Symbiose, Poitiers, France. Freddie.jeanne.richard@univ-poitiers.fr

ABSTRACT
Mate choice is mediated by many components with the criteria varying across the animal kingdom. Chemical cues used for mate attractiveness can also reflect mate quality. Regarding the gregarious species Armadillidium vulgare (isopod crustacean), we tested whether individuals can discriminate conspecifics at two different levels (between sex and physiological status) based on olfactory perception. Tested conspecifics were individuals of the same or opposite sex, with the females at different moult stages. We found that the attractiveness of individuals was mediated by short-distance chemical cues and tested individuals were able to discriminate and prefer individuals of the opposite sex. Moreover, male preference to female increased during their moulting status as they matured. Males were particularly more attracted by females with appearing white calcium plates, which corresponds to the beginning of their higher receptivity period. These differences in attractiveness due to sex and physiological status are likely to shape the composition of aggregates and facilitate mate finding and optimize the reproductive success for both males and females. Thus aggregation pheromones could be linked to sex pheromones in terrestrial isopods.

Show MeSH
Related in: MedlinePlus