Myrmecophilus ant crickets (Orthoptera: Myrmecophilidae) are typical ant guests. In Japan, about 10 species are recognized on the basis of morphological and molecular phylogenetic frameworks. Some of these species have restricted host ranges and behave intimately toward their host ant species (i.e., they are host specialist). We focused on one species, M. tetramorii, which uses the myrmicine ant Tetramorium tsushimae as its main host. All but one M. tetramorii individuals were collected specifically from nests of T. tsushimae in the field. However, behavioral observation showed that all individuals used in the experiment received hostile reactions from the host ants. There were no signs of intimate behaviors such as grooming of hosts or receipt of mouth-to-mouth feeding from hosts, which are seen in some host-specialist Myrmecophilus species among obligate host-ant species. Therefore, it may be that M. tetramorii is the species that is specialized to exploit the host by means other than chemical integration. 1. Introduction Myrmecophilus (Orthoptera: Myrmecophilidae) is the only genus of orthopteran myrmecophilous insect [1]. About 60 species are described, and all of them are myrmecophilous species. These inquiline crickets live in ant nests and exploit food resources in diverse ways (i.e., eating ant eggs, larvae, and nest debris; licking the surfaces of the ants’ bodies; disrupting ant trophallaxis; or feeding via direct mouth-to-mouth transfer) [2–8]. Some Myrmecophilus species mimic the ant colony’s chemicals by acquiring cuticular hydrocarbons from the ants via physical contact to establish a “chemical mimicry” [5–7]. In Japan, at least 10 species of Myrmecophilus are recognized on the basis of differences in the surface structure of the body and are collected from the nests of specific ant species [9]. By using molecular phylogenetic methods, we previously found [10] that Japanese Myrmecophilus crickets can be grouped into at least two types on the basis of their host specificity: one is commensally associated with a few ant species (specialist) and the other with many ant species or genera (generalist). This interesting differentiation of host specificities among congeneric species raises the question of whether behavioral differentiation also occurs. The host ranges of some parasitic organisms are associated with the organisms’ degree of behavioral specialization in relation to exploitation of food resources [11–14]. We observed the parasitic behaviors of two types of Myrmecophilus species, one of which used only a few ant species, the other,
References
[1]
D. H. Kistner, “The social insects' bestiary,” in In Social Insects, H. R. Hermann, Ed., vol. III, pp. 1–244, Academic Press, New York, NY, USA, 1982.
[2]
E. Wasmann, “Zur Lebensweise der Ameisengrillen (Myrmecophila),” Natur und Offenbarung, vol. 47, pp. 129–152, 1901.
[3]
K. H？lldobler, “Studien uber die Ameisengrille (Myrmecophila acervorum Panzer) im mittleren Maingebiet,” Mitteilungen der Schweizerischen Entomologischen Gesellschaft, vol. 20, no. 7, pp. 607–648, 1947.
[4]
W. M. Wheeler, “The habits of Myrmecophila nebrascensis Bruner,” Psyche, vol. 9(1900), no. 294, pp. 111–115, 1900.
[5]
G. Henderson and R. D. Akre, “Biology of the myrmecophilous cricket, Myrmecophila manni, Orthoptera: Gryllidae,” Journal of the Kansas Entomological Society, vol. 59, no. 3, pp. 454–467, 1986.
[6]
H. Sakai and M. Terayama, “Host records and some ecological information of the ant cricket Myrmecophilus sapporensis Matsumura,” Ari, vol. 19, pp. 2–5, 1995 (Japanese).
[7]
T. Akino, R. Mochizuki, M. Morimoto, and R. Yamaoka, “Chemical camouflage of myrmecophilous cricket Myrmecophilus sp. to be integrated with several ant species,” Japanese Journal of Applied Entomology and Zoology, vol. 40, no. 1, pp. 39–46, 1996.
[8]
T. Komatsu, M. Maruyama, and T. Itino, “Behavioral differences between two ant cricket species in nansei islands: host-specialist versus host-generalist,” Insectes Sociaux, vol. 56, no. 4, pp. 389–396, 2009.
[9]
M. Maruyama, “Four new species of Myrmecophilus (Orthoptera, Myrmecophilidae) from Japan,” Bulletin of the National Science Museum Series A, vol. 30, no. 1, pp. 37–44, 2004.
[10]
T. Komatsu, M. Maruyama, S. Ueda, and T. Itino, “mtDNA phylogeny of japanese ant crickets (Orthoptera: Myrmecophilidae): diversification in host specificity and habitat use,” Sociobiology, vol. 52, no. 3, pp. 553–565, 2008.
[11]
W. Sheehan, “Response by generalist and specialist natural enemies to agroecosystem diversification: a selective review,” Environmental Entomology, vol. 15, no. 3, pp. 456–461, 1986.
[12]
L. E. M. Vet and M. Dicke, “Ecology of infochemical use by natural enemies in a tritrophic context,” Annual Review of Entomology, vol. 37, pp. 141–172, 1992.
[13]
D. E. Dussourd, “Plant exudates trigger leaf-trenching by cabbage loopers, Trichoplusia ni (Noctuidae),” Oecologia, vol. 112, no. 3, pp. 362–369, 1997.
[14]
E. A. Bernays, T. Hartmann, and R. F. Chapman, “Gustatory responsiveness to pyrrolizidine alkaloids in the Senecio specialist, Tyria jacobaeae (Lepidoptera, Arctiidae),” Physiological Entomology, vol. 29, no. 1, pp. 67–72, 2004.
[15]
T. Komatsu, M. Maruyama, and T. Itino, “Differences in host specificity and behavior of two ant cricket species (Orthoptera: Myrmecophilidae) in Honshu, Japan,” Journal of Entomological Science, vol. 45, no. 3, pp. 227–238, 2010.
[16]
M. Maruyama, “Family Myrmecophilidae Saussure,” in Orthoptera of the Japanese Archipelago in Color, Orthopterological Society of Japan, Ed., pp. 490–492, Hokkaido University Press, Sapporo, Japan, 1870.
[17]
R Development Core Team, R: A Language and Environment for Statistical Computing, R Foundation for statistical computing, Vienna, Austria, 2005, http://www.r-project.org/.
[18]
J. Retana and X. Cerdá, “Agonistic relationships among sympatric Mediterranean ant species (Hymenoptera: Formicidae),” Journal of Insect Behavior, vol. 8, no. 3, pp. 365–380, 1995.
[19]
K. Fiedler, “Effects of larval diet on myrmecophilous qualities of Polyommatus icarus caterpillars (Lepidoptera: Lycaenidae),” Oecologia, vol. 83, no. 2, pp. 284–287, 1990.
