Native and non-native sources of carbohydrate correlate with abundance of an invasive ant

Lori Lach,Benjamin D Hoffmann,Melinda L Moir

doi:10.3897/neobiota.63.57925

Lori Lach, Benjamin D Hoffmann + Show 1 more

Open Access

https://doi.org/10.3897/neobiota.63.57925

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Journal: NeoBiota	Publication Date: Dec 17, 2020
Citations: 7	License type: CC BY 4.0

Affiliation: James Cook University, University of Western Australia

Abstract

Invasive species threaten many ecological communities and predicting which communities and sites are invasible remains a key goal of invasion ecology. Although invasive ants often reach high abundances in association with plant-based carbohydrate resources, the source and provenance of these resources are rarely investigated. We characterized carbohydrate resources across ten sites with a range of yellow crazy ant abundance in Arnhem Land, Australia and New Caledonia to determine whether yellow crazy ant (Anoplolepis gracilipes) abundance and trophic position correlate with carbohydrate availability, as well as the relative importance of native and non-native sources of carbohydrates to ant diet. In both locations, measures of yellow crazy ant abundance strongly positively correlated with carbohydrate availability, particularly honeydew production, the number of tended hemipterans, and the number of plants with tended hemipterans. In Arnhem Land, 99.6% of honeydew came from native species, whereas in New Caledonia, only 0.2% of honeydew was produced by a native hemipteran. More honeydew was available in Australia due to three common large-bodied species of Auchenorrhyncha honeydew producers (treehoppers and leafhoppers). Yellow crazy ant trophic position declined with increasing yellow crazy ant abundance indicating that in greater densities the ants are obtaining more of their diet from plant-derived resources, including honeydew and extrafloral nectar. The relationships between yellow crazy ant abundance and carbohydrate availability could not be explained by any of the key environmental variables we measured at our study sites. Our results demonstrate that the positive correlation between yellow crazy ant abundance and honeydew production is not contingent upon the provenance of the hemipterans. Native sources of carbohydrate may play an underappreciated role in greatly increasing community invasibility by ants.

Highlights

Many hypotheses to explain invasion success focus primarily on the traits of introduced species while fewer consider the characteristics of the recipient community (Catford et al 2009)
Total yellow crazy ant abundance at the nine cat food and jam lure stations combined for each site ranged from 187–722 in Arnhem Land and 378–758 in New Caledonia (Table 1)
In Arnhem Land 99.6% of honeydew came from native species, whereas in New Caledonia, only 0.2% of honeydew was produced by a native hemipteran (Table 1)

Summary

Introduction

Many hypotheses to explain invasion success focus primarily on the traits of introduced species while fewer consider the characteristics of the recipient community (Catford et al 2009). Introduced species that are able to acquire resources either by outcompeting native species, filling empty niches, or capitalizing on resource pulses are more likely to be invasive (Gonzalez et al 2010; Li and Stevens 2012). Some of these resources are acquired via interactions with resident species. Interactions in which native species provide resources are perhaps less appreciated, but not necessarily less important (Northfield et al 2018)

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