Male-biased sex ratios and plasticity in post-insemination behaviour in the New Zealand stick insect Micrarchus hystriculeus

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The duration of mate guarding by males is predicted to vary in accordance with the risk of sperm competition or mate encounter rate. Mate guarding is predicted to be prolonged under a male-biased sex ratio because the risk of sperm competition is high or the mate encounter rate is low. A consistently male-biased sex ratio should thus select for greater mate fidelity, and reduced plasticity in guarding behaviour, by males. Micrarchus hystriculeus Westwood (Phasmatodea) is a sexually size dimorphic stick insect in which males form prolonged post-insemination associations with their mates and whose populations have a consistently male-biased sex ratio. My laboratory experiments showed, as predicted, little plasticity by males in the duration of their post-insemination association. Although mate guarding duration is similar under male- and female-biased sex ratios, males clasped the genitalia of their mates significantly more often under a male-biased sex ratio, suggesting that males intensify their guarding with increasing risk of sperm competition.



AlcockJ. (1994). Postinsemination associations between males and females in insects: the mate-guarding hypothesis. — Annu. Rev. Entomol. 39: 1-21.

AlcockJ.ForsythA. (1988). Post-copulatory aggression toward their mates by males of the rove beetle Leistotrophus versicolor (Coleoptera, Staphylinidae). — Behav. Ecol. Sociobiol. 22: 303-308.

Alonso-PimentelH.PapajD. (1996). Operational sex ratio versus gender density as determinants of copulation duration in the walnut fly, Rhagoletis juglandis (Diptera: Tephritidae). — Behav. Ecol. Sociobiol. 39: 171-180.

ArnqvistG.NilssonT. (2000). The evolution of polyandry: multiple mating and female fitness in insects. — Anim. Behav. 60: 145-164.

ArnqvistG.RoweL. (2005). Sexual conflict. — Princeton University Press, Princeton, NJ.

Balshine-EarnS. (1996). Reproductive rates, operational sex ratios and mate choice in St. Peter’s fish. — Behav. Ecol. Sociobiol. 39: 107-116.

BatesD.MaechlerM.BolkerB.WalkerS.EigenC. (2014). Linear mixed-effects models using Eigen and S4, version 1.1-6. — Available online at

BondurianskyR. (2001). The evolution of male mate choice in insects: a synthesis of ideas and evidence. — Biol. Rev. 76: 305-339.

CarrollS.P. (1991). The adaptive significance of mate guarding in the soapberry bug, Jadera haematoloma (Hemiptera: Rhopalidae). — J. Insect Behav. 4: 509-530.

CarrollS.P.LoyeJ.E. (1990). Male-biased sex ratios, female promiscuity, and copulatory mate guarding in an aggregating tropical bug, Dysdercus bimaculatus. — J. Insect Behav. 3: 33-48.

ClarkS.J. (1988). The effects of operational sex ratio and food deprivation on copulation duration in the water strider (Gerris remigis Say). — Behav. Ecol. Sociobiol. 23: 317-322.

de JongK.ForsgrenE.SandvikH.AmundsenT. (2012). Measuring mating competition correctly: available evidence supports operational sex ratio theory. — Behav. Ecol. 23: 1170-1177.

delBarco-TrilloJ. (2011). Adjustment of sperm allocation under high risk of sperm competition across taxa: a meta-analysis. — J. Evol. Biol. 24: 1706-1714.

DickJ.ElwoodR.W. (1996). Effects of natural variation in sex ratio and habitat structure on mate-guarding decisions in amphipods (Crustacea). — Behaviour 133: 985-996.

EdwardD.A.ChapmanT. (2011). The evolution and significance of male mate choice. — Trends Ecol. Evol. 26: 647-654.

EmlenS.T.OringL.W. (1977). Ecology, sexual selection, and the evolution of mating systems. — Science 197: 215-223.

GwynneD.T. (1993). Food quality controls sexual selection in Mormon crickets by altering male mating investment. — Ecology 74: 1406-1413.

KellyC.D. (2008). Why do male tree weta aggressively evict females from galleries after mating?Ethology 114: 203-208.

KellyC.D. (2014). Sexual selection, phenotypic variation and allometry in genitalic and non-genitalic traits in the sexually size dimorphic stick insect Micrarchus hystriculeus. — Biol. J. Linn. Soc. 113: 471-484.

KellyC.D.JennionsM.D. (2011). Sexual selection and sperm quantity: meta-analyses of strategic ejaculation. — Biol. Rev. 86: 863-884.

KellyC.D.BussiereL.F.GwynneD.T. (2008). Sexual selection for male mobility in a giant insect with female-biased size dimorphism. — Am. Nat. 172: 417-423.

KlugH.HeuscheleJ.JennionsM.D.KokkoH. (2010). The mismeasurement of sexual selection. — J. Evol. Biol. 23: 447-462.

KnoxT.T.ScottM.P. (2006). Size, operational sex ratio, and mate-guarding success of the carrion beetle, Necrophila americana. — Behav. Ecol. 17: 88-96.

KumanoN.KuriwadaT.ShiromotoK.HaraguchiD.KohamaT. (2010). Effect of body size and sex ratio on male alternative mating tactics of the West Indian sweetpotato weevil, Euscepes postfasciatus. — Entomol. Exp. Appl. 135: 154-161.

KvarnemoC.AhnesjoI. (1996). The dynamics of operational sex ratios and competition for mates. — Trends Ecol. Evol. 11: 404-408.

Moreno-GarcíaM.CorderoC. (2007). On the function of male genital claspers in Stenomacra marginella (Heteroptera: Largidae). — J. Ethol. 26: 255-260.

ParkerG.A. (1970a). Sperm competition and its evolutionary effect on copula duration in the fly Scatophaga stercoraria. — J. Insect Phys. 16: 1301-1328.

ParkerG.A. (1970b). The reproductive behavior and the nature of sexual selection in Scatophaga stercoraria l. (Diptera: Scatophagidae). VII. The origin and evolution of the passive phase. — Evolution 24: 774-788.

ParkerG.A. (1974). Courtship persistence and female-guarding as male time investment strategies. — Behaviour 48: 157-184.

ReynoldsJ.D. (1996). Animal breeding systems. — Trends Ecol. Evol. 11: 68-72.

RondeauA.Sainte-MarieB. (2001). Variable mate-guarding time and sperm allocation by male snow crabs (Chionoecetes opilio) in response to sexual competition, and their impact on the mating success of females. — Biol. Bull. 201: 204-217.

SaekiY.KruseK.C.SwitzerP.V. (2005). The social environment affects mate guarding behavior in Japanese beetles, Popillia japonica. — J. Insect Sci. 5: 18.

SalmonJ.T. (1991). The stick insects of New Zealand. — Reed Books, Auckland.

SchoflG.TaborskyM. (2002). Prolonged tandem formation in firebugs (Pyrrhocoris apterus) serves mate-guarding. — Behav. Ecol. Sociobiol. 52: 426-433.

ShusterS.M.WadeM.J. (2003). Mating systems and strategies. — Princeton University Press, Princeton, NJ.

SimmonsL.W. (2001). Sperm competition and its evolutionary consequences in the insects. — Princeton University Press, Princeton, NJ.

SivinskiJ. (1978). Intrasexual aggression in the stick insects, Diapheromera veliei and D. covilleae, and sexual dimorphism in the Phasmatodea. — Psyche 85: 395-406.

SzekelyT.WeissingF.J.KomdeurJ. (2014). Adult sex ratio variation: implications for breeding system evolution. — J. Evol. Biol. 27: 1500-1512.

TherneauT.M.LumleyT. (2014). Survival analysis, version 2.37-7. — Available online at

WeirL.K.GrantJ.W.A.HutchingsJ.A. (2011). The influence of operational sex ratio on the intensity of competition for mates. — Am. Nat. 177: 167-176.

WickhamH. (2009). ggplot2: elegant graphics for data analysis. — Springer, New York, NY.

YamamuraN. (1986). An evolutionarily stable strategy (ESS) model of postcopulatory guarding in insects. — Theor. Popul. Biol. 29: 438-455.


  • The duration (days) of post-insemination association of male M. hystriculeus under a male-biased (2:1) and female-biased (1:2) sex ratio. Black circles are males that remained paired until the experiment was terminated (censored data) whereas white circles represent pairs in which dismounts occurred.

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