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

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.

WITHDRAWN: The Temporal Dynamics of Three Bacterial Endosymbionts, Wolbachia, Arsenophonus, And Rhizobiales, of the Invasive Yellow Crazy Ant (Anoplolepisgracilipes) in Taiwan are associated with Climate Extremes

“…2); thus, the symbiont compositions could serve as an indicator for the nest or re ect possible supercolony relationships, at least at ne geographic scales [36]. To the best of our knowledge, the current study revealed the intra-nest dynamics of the symbionts associated with A. gracilipes colonies for the rst time; such information is key to understanding the effects of these symbionts on possible adaptations and physiological reactions in A. gracilipes [4].…”

“…The sampling times for the Southern Hemisphere all fell within October-November and late spring to early summer; for sampling in the Northern Hemisphere, especially in the current study, the wooden boxes were sampled from June to September, i.e., during the summer period. Sampling in different seasons might therefore have interfered with the pattern of Wolbachia infection in A. gracilipes [4,8]. Furthermore, individual sites had infestations ranging in size from 10 to 50 km 2 , and between 2 and 61 ants from each site were screened by Sebastien et al [3].…”

“…Different sampling approaches re ect different scales of symbiont compositions. Because of the high variability of A. gracilipes abundance, larger-scale sampling could be a useful approach for understanding symbiont compositions across the different areas [1,4].…”

“…It is widely dispersed throughout inland areas and locations near the Paci c and Indian Oceans, and the speed with which it spreads is almost unrivaled [2]. However, the abundance of A. gracilipes varies temporally and spatially, especially in its introduced range, with some populations persisting at relatively low density, some achieving extraordinarily high densities, and some crashing for unknown reasons [3,4].…”

Towards precision ecology: Relationships of multiple sampling methods quantifying abundance for comparisons among studies

“… Standardised highest yellow crazy ant abundance reported within fourteen studies as calculated by the relationships between the three sampling methods of card counts, pitfall trapping and tuna lures using a) summed log(x+1)-transformed sample data, and b) log(x+1)-transformed pooled data. Studies are: 1) [ 30 ]; 2) [ 31 ] New Caledonia site; 3) [ 31 ] Australia site; 4) [ 21 ]; 5) [ 32 ]; 6) this study; 7) [ 33 ]; 8) [ 34 ] 9) [ 17 ]; 10) [ 35 ]; 11) [ 36 ]; 12) [ 37 ]; 13) [ 38 ]; and 14) [ 3 ]. …”