Individual Thigmotactic Preference Affects the Fleeing Behavior of the American Cockroach (Blattodea: Blattidae)

Abstract

Positive thigmotactic behavior is associated with the ability to hide from predators and is important to explain aggregation and collective patterns in various animals. For example, this behavior has been observed in woodlice, domiciliary cockroaches, ants, and fish. Lately, research on different species is focused on the importance of animal personality for ecological and evolutionary processes, individual fitness and group cohesion. In fact, it is generally expected to find some degree of interindividual consistent differences for a behavior, unless specific circumstances, like predator attacks, hide the presence of personalities. In this research, we analyzed the individual thigmotactic preference of domiciliary cockroaches (Periplaneta americana (Linnaeus, 1758) (Blattodea: Blattidae)) and how it affected the fleeing behavior of isolated individuals inside a shelter after receiving a light stimulus. We notably highlight how isolated individuals show different consistent preferences regarding their position in the shelter, which is due to the individual thigmotaxis level, before the fleeing behavior. During the fleeing itself, cockroaches nearer to the wall, and therefore with more positive thigmotaxis, showed slower reaction lantencies to the stimulus. We propose that thigmotaxis homogenizes the interindividual differences among individuals and is important to explain the individual and collective fleeing behavior.

The interplay between personalities and social interactions affects the cohesion of the group and the speed of aggregation

“…Interestingly, shy groups were more cohesive when reaching this consensus, with faster aggregation and with a larger population in the selected shelter compared to bold groups ( Fig 3 ). The fitting of Eq 1 shows that these differences are mainly due to differences between joining probabilities, which is also in agreement with previous studies [ 48 , 49 , 54 ]. Even when using two equal options (i.e., identical shelters), differences in cohesion and in the way consensus is reached may have an important impact on individual survival.…”

“…These results support the first hypothesis that differences in mean individual behaviour induce differences at the group level [ 52 ] and agrees with previous studies showing individual personalities in P . americana [ 48 , 49 , 54 ]. The second hypothesis predicts that groups composed by all shy or all bold individuals differ in their cohesion and their network of social interactions, which should in turn affect the individual and group behaviour.…”

“…In this study, we use the American cockroach ( Periplaneta americana ) to investigate how the composition of personalities within a group affects the speed and the cohesion of collective decision making. Domiciliary cockroaches are a model species for the study of the aggregation process and decision making, and, more recently, personality variation [ 45 – 49 ]. Indeed, cockroaches obtain large benefits from this aggregation such as the dilution effect and a ‘many-eyes’ effect to detect predators or dangers, but they also benefit from a decrease in water loss, which is a major risk for this species [ 50 , 51 ].…”

The effect of vertical extent of stimuli on cockroach optomotor response

“…3A) could be explained by negative phototaxis or shelter seeking (Guthrie and Tindall, 1968;Zhukovskaya et al, 2017). Positioning of the cockroaches on the trackball prevents antennal contact to solid surfaces, so the effect of thigmotaxis on response latency can be ruled out (Laurent Salazar et al, 2018). At 5 lx intensity, the latency and its variation were smaller than at 50 and 500 lx (Fig.…”

The role of personality variation, plasticity and social facilitation in cockroach aggregation

“…Experiments were carried out on adult male without external damage (see Laurent Salazar et al, 2018; Planas-Sitjà et al, 2015 for more information). The experimental set-up was a circular arena, covered with a paper layer (120 g/m 2 ), surrounded by a black polyethylene ring (diameter: 100 cm, height: 20 cm) with a light source (four General Electric Energy-saving light bulbs, 23 W, 2700 K) placed above the set-up.…”