Dynamic multimodal interactions in navigating wood ants: What do path details tell us about cue integration?

Abstract

Ants are expert navigators using multiple cues from multiple sensory modalities to navigate successfully. Here, we present the results of systematic studies of multimodal cue use in navigating wood ants, Formica rufa. Ants learnt to navigate to a feeder that was defined by an olfactory cue, visual cue and airflow presented together. When ants learnt to find a feeder that was placed in the centre of the visual cue, well-trained ants were not anymore able to accurately approach the feeder when either the olfactory or visual cue were removed in tests. This confirms that some form of cue binding has taken place. However, in a visually simpler task with the feeder located at the edge of the visual cue, ants still approached the feeder accurately when individual cue components were removed. Hence, cue binding is flexible and depends on the navigational context. In general, cues act additively in determining the ants’ paths accuracy, i.e. the use of multiple cues increased navigation performance. Moreover, across different training conditions, we saw different motor patterns in response to different sensory cues. For instance, ants had more sinuous paths with more turns when they followed an odour plume but did not have any visual cues. Having visual information with the odour enhanced performance and therefore positively impacted on plume following. Interestingly, paths characteristics of ants from the two multimodal groups with a different visual task were different, suggesting that the observed flexibility in cue binding may be a result of the ants’ movement characteristics.Summary statementWe investigated the impact of multimodal information on navigating ants. Ants showed flexible response to multimodal information depending on the sensori-motor contingencies of the navigation task.

Innate visual attraction in wood ants is a hardwired behavior seen across different motivational and ecological contexts

“…Many insects show intrinsic visuomotor response, i.e., they show fixed motor behaviors in response to specific visual input. Wood ant foragers show an innate attraction to large and conspicuous objects (Buehlmann et al, 2020a; Buehlmann et al, 2020c; Graham et al, 2003; Voss, 1967), whereas foragers from other ant species with different foraging ecologies show innate attractions different to wood ants (e.g. (Collett, 2010; Heusser and Wehner, 2002)).…”

“…Conspicuous objects initiate innate behavior in many insects, including ants (fruit flies: (Gotz, 1987; Strauss and Pichler, 1998; Wehner, 1972), locusts: (Wallace, 1962), ladybirds: (Collett, 1988), mantids: (Poteser and Kral, 1995), leaf hoppers: (Brackenbury, 1996), ants: (Buehlmann et al, 2020a; Buehlmann et al, 2020c; Collett, 2010; Graham et al, 2003; Heusser and Wehner, 2002; Voss, 1967)), with many of these innate behaviors being ecologically tuned (e.g. prey detection, predator avoidance or landing site detection).…”

“…Similarly, innate visual responses of different ant species are tailored to the ants’ habitat. Whereas wood ant foragers are attracted to large conspicuous objects (Buehlmann et al, 2020a; Buehlmann et al, 2020c; Graham et al, 2003; Voss, 1967), desert ants avoid them (Collett, 2010; Heusser and Wehner, 2002). Wood ants ( Formica rufa ) inhabit cluttered woodland habitat where they predominantly feed on honeydew from aphids on trees (Domisch et al, 2016).…”

Impact of central complex lesions on visual orientation in ants: Turning behaviour, but not the overall movement direction, is disrupted

“…part of their navigational repertoire (Voss 1967;Graham et al 2003;Buehlmann et al 2020a;Buehlmann et al 2020c;Buehlmann & Graham 2021). This innate behaviour can form the basis for learnt foraging routes (Graham et al 2003).…”