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Unformatted text preview: ORIGINAL PAPER Consumption of introduced prey by native predators: Argentine ants and pit-building ant lions Stephanie Glenn David Holway Received: 17 May 2006 / Accepted: 1 June 2007 / Published online: 20 June 2007 Springer Science+Business Media B.V. 2007 Abstract When populations of native predators are subsidized by numerically dominant introduced spe- cies, the structure of food webs can be greatly altered. Surprisingly little is known, however, about the general factors that influence whether or not native predators consume introduced species. To learn more about this issue, we examined how native pit-building ant lions ( Myrmeleon ) are affected by Argentine ant ( Linepithema humile ) invasions in coastal southern California. Compared to areas without L. humile , invaded areas contained few native ant species and were deficient in medium-sized and large bodied native ants. Based on these differences, we predicted that Argentine ants would negatively affect ant lion larvae. Contrary to this expectation, observational surveys and laboratory growth rate experiments revealed that Myrmeleon were heavier, had longer mandibles, and grew more quickly when their main ant prey were Argentine ants rather than native ants. Moreover, a field transplant experiment indicated that growth rates and pupal weights were not statistically different for larval ant lions reared in invaded areas compared to those reared in uninvaded areas. Argen- tine ants were also highly susceptible to capture by larval Myrmeleon . The species-level traits that pre- sumably make Argentine ant workers susceptible to capture by larval ant lionssmall size and high activity levelsappear to be the same characteristics that make them unsuitable prey for vertebrate preda- tors, such as horned lizards. These results underscore the difficulties in predicting whether or not numer- ically dominant introduced species serve as prey for native predators. Keywords California Linepithema humile Invasion Myrmeleon Predation Introduction Studies on biological invasions commonly address non-native species that either compete with native taxa or consume them. By comparison, much less is known about the importance of introduced species as prey for native consumers. When non-native species become common, however, they can serve as key sources of food (Maerz et al. 2005 ; King et al. 2006 ). Numerical responses of native consumers to subsidies of non-native prey can intensify levels of predation on native prey (Noonburg and Byers 2005 ) and even increase the prevalence of disease (Pearson and S. Glenn D. Holway ( & ) Section of Ecology, Behavior, and Evolution, Division of Biological Sciences, MC 0116, University of California at San Diego, La Jolla, CA 92093-0116, USA e-mail: firstname.lastname@example.org Present Address: S. Glenn Cabrillo National Monument, 1800 Cabrillo Memorial Dr., San Diego, CA 92106, USA e-mail: Stephanie_Glenn@nps.gov 123 Biol Invasions (2008) 10:273280 DOI 10.1007/s10530-007-9128-7 Callaway...
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This note was uploaded on 01/06/2010 for the course EVE 101 taught by Professor Strong,d during the Spring '08 term at UC Davis.
- Spring '08