Between-species differences of behavioural repertoire of castes in the ant genus Pheidole : a methodological artefact?

Abstract

This study highlights the influence of sampling size on the interpretation of between castes division of labour in the dimorphic ant genus Pheidole. We show that data analyses based on rarefaction curves provide better estimates of caste repertoire sizes. Weighted observations of the two worker castes of Pheidole pallidula reveals that the behavioural repertoire of majors is far more extended than expected. Indeed, majors are not restricted to defence, seed milling or food storage but can additionally participate to within nest activities by carrying out 69 % of the minors' behavioural repertoire including brood care. Besides, we show that interspecific variation in the size of majors' behavioural repertoire could simply result from differences in the number of majors observed. Therefore, the ergonomic prediction that the repertoire size of one caste should be correlated to its numerical representation in the colony needs to be re-examined considering between-castes differences in the sampling effort.

Behavior ofPaussus favieri(Coleoptera, Carabidae, Paussini): A Myrmecophilous Beetle Associated withPheidole pallidula(Hymenoptera, Formicidae)

“…The ants lick all exposed parts of the beetle's body that are rich in trichomes (antennae, head, legs, elytra and pygidium) (Figures 2(a), 2(e), and 2(f)). This licking behavior is very similar to the ants' allogrooming behavior ( [31] and references therein). The ants spend most time licking the trichomes on the basal spur and the pockets of the antennae (Figures 2(c) and 2(d)).…”

“…The behaviors performed by P. pallidula during the interactions with the beetles were described following the behavioral repertoire suggested by Hölldobler and Wilson [1], Passera and Aron [30], and Sempo and Detrain [31]. Beetle cleaning and sexual behaviors were described after analyzing the videos in slow motion.…”

“…The ants antennate frenetically and widely open their mandibles, similarly to alarm behaviors performed during dangerous situations [1,31]. This behavior is rarely observed against beetles, but when it is, it is not followed by biting.…”

Starvation drives a threshold triggering communication

“…In ants, honeybees and bumblebees, response thresholds of a given individual are regulated by several internal factors such as genetic predisposition, physiology, physical caste, age or individual experience (e.g. Detrain and Pasteels, 1991;Detrain et al, 1999;Fewell and Page, Jr, 2000;Huang and Otis, 1991;Page et al, 1997;Robinson, 1992;Robinson and Page, 1995;Sempo and Detrain, 2004;Weidenmüller et al, 2002). However, such thresholds can also vary in relation to several external factors such as the ant's demand for food (Suds and Suds, 1985), distance from nest to food patches (Breed et al, 1996), or presence of amino acids in honeydew (Lanza et al, 1992).…”

Spatial organization in a dimorphic ant: caste specificity of clustering patterns and area marking

“…Similarly, the caste specificity in P. pallidula aggregative behavior can be related to differences in the activity rate and mobility level of minors and majors. Indeed, P. pallidula minors, which represent around 90% of the population (Passera 1977), are also the most active workers as well as the most mobile both inside (Sempo and Detrain 2004) and outside the nest (Detrain and Pasteels 1991). Around 60% of minors within the nest are moving or engaged in a task performance (Sempo and Detrain 2004).…”