Category Archives: Uncategorized

A Year in an Ant’s life

There is a new article by Stephane Caut and colleagues from Spain on the funnel ant, Aphaenogaster senilis. They studied resource use by these ants over an entire year and attempt to attribute the variation to colony life cycle and resource availability.

Ref: Caut S, Barroso A, Cerdá X, Amor F & Boulay RR. 2013. A Year in an Ant’s life: Opportunism and Seasonal Variation in the Foraging Ecology of Aphaenogaster senilis. Ecoscience 20: 19-27.

Abstract: Ants are important consumers in most terrestrial ecosystems. They show a great diversity of diets and foraging strategies. Here, we analyzed how circannual variation in resource use by the Mediterranean species Aphaenogaster senilis is related to colony life cycle and resource availability. In southwestern Spain, this species is active almost year-round, but foraging intensity decreases 10-fold between March and November, following larval production. In the summer, ants refrain from foraging at midday to avoid high temperatures. We hypothesized that diet and foraging plasticity could also explain the ecological success of this species. There are several techniques for assessing the diet of ants. Combining isotope analyses with conventional methods can provide better taxonomic resolution of resource utilization. Using a combination of classic and isotopic analyses, we found that 1) the proportion of plant and animal-derived items collected by foragers did not vary significantly from March to November, and 2) isotope analyses indicated a decrease in the trophic level of A. senilis between June and September, suggesting a difference between collected material and items assimilated. Interestingly, most animal prey were collected by individual ants, and many were retrieved alive. Therefore, A. senilis is not only a scavenger, but also a non-negligible predator, particularly of aphids. The abundance of the most common animal-derived items in the diet was proportional to their abundance in the study area. We conclude that A. senilis is an opportunistic species that is able to feed on a variety of resources, which may be key to its ecological success.

Backtracking behaviour in lost ants

Wystrachetal_2013A new article by Antoine Wystrach and his colleagues from Macquarie University have a publication on the charming Australian desert ant Melophorus bagoti. It is a nice story about lost ants exhibiting a strategy called ‘backtracking’. And it is always nice to see a ant navigation story featured on the cover.

Reference: Wystrach A, Schwarz S, Baniel A, Cheng K. 2013. Backtracking behaviour in lost ants: an additional strategy in their navigational toolkit. Proc R Soc B 280: 20131677

Abstract: Ants use multiple sources of information to navigate, but do not integrate all this information into a unified representation of the world. Rather, the available information appears to serve three distinct main navigational systems: path integration, systematic search and the use of learnt information—mainly via vision. Here, we report on an additional behaviour that suggests a supplemental system in the ant’s navigational toolkit: ‘backtracking’. Homing ants, having almost reached their nest but, suddenly displaced to unfamiliar areas, did not show the characteristic undirected headings of systematic searches. Instead, these ants backtracked in the compass direction opposite to the path that they had just travelled. The ecological function of this behaviour is clear as we show it increases the chances of returning to familiar terrain. Importantly, the mechanistic implications of this behaviour stress an extra level of cognitive complexity in ant navigation. Our results imply: (i) the presence of a type of ‘memory of the current trip’ allowing lost ants to take into account the familiar view recently experienced, and (ii) direct sharing of information across different navigational systems. We propose a revised architecture of the ant’s navigational toolkit illustrating how the different systems may interact to produce adaptive behaviours.