Distribution of the introduced Argentine ant (Iridomyrmex humilis) in natural habitats of the lower Sacramento Valley and its effects on the indigenous ant fauna
AuthorPhilip S. Ward
Author AffiliationsPhilip S. Ward was Associate Professor, Department of Entomology, University of California, Davis, California 95616.
Hilgardia 55(2):1-16. DOI:10.3733/hilg.v55n02p016. April 1987.
This study was designed to determine the extent to which the introduced Argentine ant (Iridomyrmex humilis), a pest in urban and agricultural environments, has invaded natural habitats in the lower Sacramento Valley, and its effects on the native ant fauna. Of four natural habitats surveyed (valley riparian woodland, foothill riparian woodland, blue oak-digger pine woodland, and chaparral), at 46 sites in Yolo and Solano counties, only valley riparian woodland was found to have been colonized by I. humilis. Riparian woodland sites occupied by I. humilis have permanent sources of water and tend to be environmentally degraded. Populations of I. humilis are common but patchily distributed along four principal riparian systems in Yolo and Solano counties (Ulatis Creek, Putah Creek, Cache Creek, and the Sacramento River). Observations indicate that patches of semidisturbed riparian woodland provide refuges from which populations of I. humilis may invade adjacent agricultural land, and vice versa. The species richness of native ants is markedly reduced at riparian woodland sites occupied by I. humilis. Among the common native ants, epigaeic (aboveground foraging) species are more susceptible to displacement by I. humilis than are hypogaeic species. The three most adversely affected species (Liometopum occidentale, Tapinoma sessile, and Formica occidua [ = moki]), which are absent from sites colonized by I. humilis, are dominant epigaeic ants; two of the three least displaced species (Stenamma diecki and S. californicum) are timid, cryptobiotic ants that forage in soil and leaf litter.
Anonymous. Two California beetles listed as threatened. Endangered Species Tech. Bull. 1980. 5:6-7.
Barber E. R. The Argentine ant: distribution and control in the United States. U.S. Dept. Agr., Bull. 1916. 377:1-23. DOI: 10.5962/bhl.title.64570 [CrossRef]
Bond W., Slingsby P. Collapse of an ant-plant mutualism: the Argentine ant (Iridomyrmex humilis) and myrmecochorous Proteaceae. Ecology. 1984. 65:1031-37.
Crowell K. L. Rates of competitive exclusion by the Argentine ant in Bermuda. Ecology. 1968. 49:551-55. DOI: 10.2307/1934122 [CrossRef]
DeBach P. The necessity of an ecological approach to pest control on citrus in California. J. Econ. Entomol. 1951. 44:443-47.
Eckert J. E., Mallis A. Ants and their control in California. Univ. Calif. Agric. Exp. Station Circ. 1937. 342:1-37. DOI: 10.5962/bhl.title.59682 [CrossRef]
Erickson J. M. The displacement of native ant species by the introduced Argentine ant Iridomyrmex humilis Mayr. Psyche. 1972. 78:257-66.
Flanders S. E. Coincident infestations of Aomidiella citrina and Coccus hesperidium, a result of ant activity. J. Econ. Entomol. 1945. 38:711-12.
Flanders S. E. The role of the ant in the biological control of scale insects in California. Proc. 10th Int. Congr. Entomol. 1958. 4:579-82.
Fluker S. S., Beardsley J. W. Sympatric associations of three ants: Iridomyrmex humilis, Pheidole megacephala and Anoplolepis longipes in Hawaii. Ann. Entomol. Soc. Amer. 1970. 63:1290-96.
Haskins C. P., Haskins E. F. Pheidole megacephala and Iridomyrmex humilis in Bermuda—equilibrium or slow replacement?. Ecology. 1965. 46:736-40. DOI: 10.1111/j.1365-2699.2011.02490.x [CrossRef]
Küchler A. W., Barbour M. G., Major J. Appendix: the map of the natural vegetation of California. The terrestrial vegetation of California. 1977. New York: Wiley and Sons. p. 909-38. and accompanying map
Lieberburg I., Kranz P. M., Seip A. Bermudian ants revisited: the status and interaction of Pheidole megacephala and Iridomyrmex humilis. Ecology. 1975. 56:473-78.
Mallis A. Army ants in California. Sci. Monthly. 1938. 47:220-26.
Markin G. P. The seasonal life cycle of the Argentine ant, Iridomyrmex humilis (Hymenoptera, Formicidae) in southern California. Ann. Ent. Soc. Amer. 1970. 63:1238-42.
Michener C. D. The history and behavior of a colony of harvester ants. Sci. Monthly. 1942. 55:248-58.
Newell W., Barber T. C. The Argentine ant. U.S. Dept. Agr. Bull. 1913. 122:1-98. DOI: 10.5962/bhl.title.36907 [CrossRef]
Pasfield G. Argentine ants. Aust. Nat. History. 1968. 16:12-15.
Roberts W. G., Howe J. G., Major J., Sands A. A survey of riparian forest flora and fauna in California. Riparian forests in California, their ecology and conservation. A symposium sponsored by the Institute of Ecology and the Davis Audubon Society. 1980. Univ. Calif. Berkeley. p. 3-19. Div. Agric. Sci. Publ. 4101
Shapley H. Notes on Pterergates in the California harvester ant. Psyche. 1920. 27:72-74. DOI: 10.1155/1920/73165 [CrossRef]
Skaife S. H. The study of ants. 1961. London: Longmans Green and Co.
Smith M. R. House-infesting ants of the eastern United States, their recognition, biology, and economic importance. U.S. Dept. Agr., Tech. Bull. 1965. 1326:1-105.
Tremper B. D. Distribution of the Argentine ant, Iridomyrmex humilis Mayr, in relation to certain native ants of California: ecological, physiological, and behavioral aspects 1976. Ph.D. Thesis, Univ. Calif., Berkeley
Wheeler W. M. On certain tropical ants introduced into the United States. Entomol. News. 1906. 17:23-26.
Woodworth C. W. The Argentine ant in California. Univ. Calif. Agric. Exp. Sta. Circ. 1908. 38:1-11.
Woodworth C. W. The control of the Argentine ant. Univ. Calif. Agric. Exp. Sta. Bull. 1910. 207:53-82.
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