In the stored-product beetle, the broad-horned flour beetle, Gnatocerus cornutus (Fabricius), all males possess enlarged mandibles, widened gena, and a pair of small horns on the vertex, but females lack these completely. Observations of male-male interactions of G. cornutus showed that larger individuals won male-male fights, and that the mandibles were used as weapons. Morphological analysis based on the non-linearity test of Eberhard and Gutierrez's model (1991) showed that intra-sexual dimorphism in males was only found in the mandibles used in male-male combat, but not in the gena and horns. This beetle can be an ideal model for evolutionary studies of exaggerated weapons for male combat, because rearing successive generations and observing male fighting are easy.
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REFERENCES
Andersson, M. (1994). Sexual Selection, Princeton University Press, Princeton.
Bridge, A. P., Elwood, R. W., and Dick J. T. A. (2000). Imperfect assessment and limited information preclude optimal strategies in male-male fights in the orb-weaving spider Metellina mengei. Proc. R. Soc. Lond. B. 267: 273–279.
Brown, L., and Bartalon, J. (1986). Behavioral correlates of male morphology in a horned beetle. Am. Nat. 127: 565–570.
Brown, L., and Siegfried, B. D. (1983). Effects of male horn size on courtship activity in the forked fungus beetles, Bolitotherus cornutus (Coleoptera: Tenebrionidae). Ann. Entomol. Soc. Am. 76: 253–255.
Eberhard, W. G. (1979). The function of horns in Podischnus agenor (Dynastinae) and other beetles. In Blum, M. S., and Blum, N. A. (eds.), Sexual and Reproductive Competition in Insects, Academic Press, New York, pp. 231–258.
Eberhard, W. G. (1980). Horned beetle. Sci. Am. 242: 124–131.
Eberhard, W. G. (1998). Sexual behavior of Acanthocephala declivis guatemalana (Hemiptera: Coreidae) and the allometric scaling of their modified hind legs. Ann. Entomol. Soc. Am. 91: 863–871.
Eberhard, W. G., and Gutierrez, E. E. (1991). Male dimorphisms in beetles and earwigs and question of developmental constraints. Evolution 45: 18–28.
Eberhard, W. G., Garcia-C, J. M., and Lobo, J. (2000). Size-specific defensive structures in a horned weevil confirm a classic battle plan: avoid fights with larger opponents. Proc. R. Soc. Lond. B 267: 1129–1134.
Emlen, D. J. (1996). Artificial selection on horn body-length size allometry in the horned beetle Onthophagus acuminatus (Coleoptera: Scarabaeidae). Evolution 50: 1219–1230.
Emlen, D. J., and Nijhout, H. F. (2000). The development and evolution of exaggerated morphologies in insects. Annu. Rev. Entomol. 45: 661–708.
Emlen, S. T., and Oring, L. W. (1977). Ecology, sexual selection, and the evolution of mating systems. Science 197: 215–223.
Enders, M. M., Schule, H., and Henschel, J. H. (1998). Sexual dimorphism, fighting success and mating tactics of male Onymacris plana Peringuey (Coleoptera: Tenebrionidae) in the Namib Desert. Ethology 104: 1003–1019.
Goldsmith, S. K. (1985). Male dimorphism in Dendrobias mandibularis Audinet-Serville (Coleoptera: Cerambycidae). J. Kans. Entomol. Soc. 58: 534–538.
Gould, S. J. (1966). Allometry and size in ontogeny and phylogeny. Biol. Rev. 41: 587–640.
Hanley, R. S. (2001). Mandibular allometry and male dimorphism in a group of obligately mycophagous beetles (Insecta: Coleoptera: Staphylinidae: Oxyporinae). Biol. J. Linn. Soc. 72: 451–459.
Huxley, J. S. (1972). Problems of Relative Growth, 2nd edn , Dover, New York.
Knell, R. J., Pomfret, C. J., and Tomkins, J. L. (2004). The limits of elaboration: curved allometries reveal the constraints on mandible size in stag beetles. Proc. R. Soc. Lond. B 271: 523–528.
Kotiaho, J. S., Simmons, L. W., Hunt, J., and Tomkins, J. L. (2003). Males influence maternal effects that promote sexual selection: A quantitative genetic experiment with dung beetles Onthophagus taurus. Am. Nat. 161: 852–859.
Kurosawa, Y., Hisamatsu, S., and Sasaji, H. (1985). Colored Illustrations of the Coleoptera of Japan, Vol. III, Hoikusha Publishing, Osaka, Japan.
Miller, K. B., and Wheeler, Q. D. (2005). Asymmetrical male mandibular horns and mating behavior in Agathidium Panzer (Coleoptera: Leiodidae). J. Nat. Hist. 39: 779–792
Miyatake, T. (1993). Male-male aggressive behavior is changed by body size difference in the leaf-footed plant bug Leptoglossus australis, Fabricius (Heteroptera: Coreidae). J. Ethol. 11: 63–65.
Moczek, A. P. (2003). The behavioral ecology of threshold evolution in a polyphenic beetle. Behav. Ecol. 14: 841–854.
Okada, K., and Miyatake, T. (2004). Sexual dimorphism in mandibles and male aggressive behavior in the presence and absence of female in the beetle Librodor japonicus (Coleoptera: Nitidulidae). Ann. Entomol. Soc. Am. 97: 1342–1346.
Otte, D., and Stayman, J. (1979). Beetle horns: some patterns in functional morphology. In Blum, M. S., and Blum, N. A. (eds.), Sexual and Reproductive Competition in Insects, Academic Press, New York, pp. 259–292.
Palmer, T. J. (1978). A horned beetle which fights. Nature 274: 583–584.
Salmond, K. F. (1956). The insect and mite fauna of a Scottish flour mill. Bull. Entomol. Res. 47: 621–630.
Savvidou, N., and Bell, C. H. (1994). The effect of larval density photoperiod and food change on the development of Gnatocerus Cornutus (F.) (Coleoptera: Tenebrionidae). J. stored Prod. Res. 30: 17–21.
SAS Institute. (1998). StatView 5.0 J. SAS Institute, Cary, NC.
Throne, J. E., and Cline, L. D. (1994). Seasonal flight activity and seasonal abundance of selected stored-product Coleoptera around grain storages in South Carolina. J. Agric. Entomol. 11: 321–338.
Tomkins, J. L. (1999). Environmental and genetic determinants of the male forceps length dimorphism in the European earwig Forficula auricularia. Behav Ecol Sociobiol 47: 1–8.
Tomkins, J. L., and Brown, G. S. (2004). Population density drives the local evolution of a threshold dimorphism. Nature 431: 1099–1103.
Tsuda, Y., and Yoshida, T. (1985). Population biology of the broad-horned flour beetles, Gnathocerus Cornutus (F.) II. Crowding effects of larvae on their survival and development. Res. Popul. Ecol. 27: 77–85.
Verrell, P. A. (1986). Wrestling in the red spotted newt (Notophthalmus viridescens): resource value and contestant asymmetry determine duration and outcome. Anim. Behav. 34: 398–402.
Wells, M. S. (1988). Effects of body size and resource value on fighting behaviour in a jumping spider. Anim. Behav. 36: 321–326.
Wilkinson, G. S. (1993). Artificial sexual selection alters allometry in the stalk-eyed fly Cytodiopsis dalmanni (Diptera: Diopsidae). Genet. Res. 62: 213–222.
Yoshida, T. (1958). A note of four stored product pect species newly established in Japan. Shokubutsu-Boeki 12: 59–63 (in Japanese).
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Okada, K., Miyanoshita, A. & Miyatake, T. Intra-sexual Dimorphism in Male Mandibles and Male Aggressive Behavior in the Broad-Horned Flour Beetle Gnatocerus cornutus (Coleoptera: Tenebrionidae). J Insect Behav 19, 457–467 (2006). https://doi.org/10.1007/s10905-006-9038-z
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DOI: https://doi.org/10.1007/s10905-006-9038-z