Virginie Durier

Social Integration of Robots into Groups of Cockroaches to Control Self-Organized Choices

Collective behavior based on self-organization has been shown in group-living animals from insects to vertebrates. These findings have stimulated engineers to investigate approaches for the coordination of autonomous multirobot systems based on self-organization. In this experimental study, we show collective decision-making by mixed groups of cockroaches and socially integrated autonomous robots, leading to shared shelter selection. Individuals, natural or artificial, are perceived as equivalent, and the collective decision emerges from nonlinear feedbacks based on local interactions. Even when in the minority, robots can modulate the collective decision-making process and produce a global pattern not observed in their absence. These results demonstrate the possibility of using intelligent autonomous devices to study and control self-organized behavioral patterns in group-living animals.

Path integration in cockroach larvae, Blattella germanica (L.) (insect: Dictyoptera): Direction and distance estimation

The question of how an insect finds its way between foraging areas and its shelter has been investigated in cockroaches,Blattella germanica. Our aim was to demonstrate that they integrate the characteristics of their outward trip to estimate direction and distance, which enable them to return to their shelter, relying on path integration mechanisms using kinesthetic cues. The return path pattern was characterized by a nearly linear oriented-to-the-goal trajectory, an arrest, and a systematic search at a much slower speed. The arrest position indicated that the insect’s home vector was back to zero and that it was the estimated shelter position. If the shelter failed to be at the arrest position, cockroaches started a nonrandom systematic search directed mainly around the arrest. They looped back and forth around the arrest position and increased the size of their loops with time. The pattern of this search seems to be an ubiquitous trait in insects.

Learning and foraging efficiency in German cockroaches, Blattella germanica (L.) (Insecta: Dictyoptera)

Abstract We analysed, under laboratory test conditions, how German cockroach larvae oriented their outgoing foraging trip from their shelter. Our results stressed the importance of external factors, like availability and spatial distribution of food sources, in the choice of a foraging strategy within their home range. When food sources were randomly distributed, larvae adopted a random food search strategy. When food distribution was spatially predictable and reliable, cockroaches were able to relate the presence of food with a landmark during a 3-day training period and to develop an oriented search strategy. Cockroaches were able to associate learned spatial information about their home range to the presence of food resources and then to improve their foraging efficiency. However, conflict experiments revealed that detection of food odour overrode learned landmark cues.

Effects of spatial knowledge and feeding experience on foraging choices in German cockroaches

We investigated the importance of spatial knowledge of food positions and of feeding experience on foraging choices in German cockroaches, Blattella germanica (L.). We trained cockroaches in an arena to feed on a particular food close to a landmark. To test whether the landmark helped guide cockroaches to the site, we removed the food and put the landmark in a different position. Cockroaches then went to the site indicated by the landmark. Given a choice between novel food in a new site and the known food in the known site, cockroaches preferred the novel food. But when the novel food was placed in the known site and the known food elsewhere, cockroaches were attracted to the latter. Thus, they differentiated novel food placed in a site that was previously occupied by the known food from novel food in a novel site. It seems that cockroaches learn the locations of specific resources in their home range and associate particular locations with particular resources.

Comparisons of toxic baits for controlling the cockroach, Blattella germanica: attractiveness and feeding stimulation

Female German cockroaches, Blattella germanica (L.) (Dictyoptera: Blattellidae) and nymphs (stages 1, 3 and 6) were used to test the attractiveness and the feeding stimulation of several commercial gel formulations of insecticide food baits in laboratory binary choice tests. The four toxic gel baits tested were: ‘Avert’ (0.05% abamectin = avermectin B1), ‘Drax’ (33.3% boric acid), ‘Goliath’ (0.05% fipronil) and ‘Maxforce’ (2.15% hydramethylnon). The attractiveness of a bait was estimated by the number of cockroaches that chose it first, and by their tendency to change to it secondarily. Feeding stimulation was estimated by the mean duration of feeding bouts and total duration of food intake. Variability of these factors was assessed in relation to age of cockroaches and to age of baits. With a few exceptions, cockroach age did not affect performance in any of these tests. Attractiveness to B. germanica ranked ‘Goliath’ gel higher than ‘Avert’, ‘Drax’ and ‘Maxforce’ gels, whether or not the active ingredient fipronil was present in ‘Goliath’ gel. Feeding stimulation ranked ‘Avert’ and ‘Maxforce’ gels higher than ‘Goliath’ gel, and ‘Drax’ gel was inferior. With ageing up to 3 months, the feeding stimulation power of ‘Goliath’ and ‘Maxforce’ gels increased, whereas that of ‘Avert’ fluctuated. Assuming that all types of bait effectively kill cockroaches once ingested, these results illustrate the importance of behavioural observations on bait efficiency and show that ranking of these different food baits varies in relation to the parameter analysed.

Secondary transmission of toxic baits in German cockroach (Dictyoptera: Blattellidae)

Abstract The death rates of three toxic gel baits (fipronil bait, 0.05%; hydramethylnon, bait 2.15%; and abamectin B1 bait, 0.05%) were estimated in Blattella germanica (L.). After ingestion, all three baits killed similar proportions of cockroaches, but they died more rapidly after ingestion of fipronil bait than after ingestion of abamectin B1 bait or of hydramethylnon bait. Laboratory experiments evaluated the impact of secondary transmission of fipronil bait and hydramethylnon bait. Mortality rates caused by secondary transmission were higher for fipronil bait than for hydramethylnon bait. Under controlled laboratory conditions, secondary transmission occurred mainly through direct contact with, or ingestion of, traces of baits dispersed in the environment by contaminated cockroaches. These traces were either deposited by “trampling” in the environment or on dead contaminated cockroaches. Social interactions and cannibalism played a minor role in secondary transmission of these two baits.

Influence of a novel object in the home range of the cockroach, Blattella germanica.

Abstract We investigated whether exploratory behaviour of the cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae), was modified by the introduction of a novel object, such as a bait station, into their familiar home range. In particular, we measured the attractiveness of boxes, as novel objects, in relation to their complexity and to their contents. The presence of a novel object induced an increase of exploratory behaviour on and inside the object and its environs. Time spent around the object depended on the complexity of the object (closed box or with holes). The more complex the object, the longer cockroaches spent exploring it. When the object contained food, its attractiveness was greatly increased and it affected cockroaches from further away.

Locomotor Inhibition in Adult Horses Faced to Stressors: A Single Postpartum Experience May be Enough!

Despite the number of postpartum handling that a newborn experiences, few studies focus on their long-term consequences. In rats, regular long separations from the mother, during the early life, led to modifications of the locomotor activity when the animal is confronted to a stressor. In horses, one component of the behavioral response to stressful situation is active locomotion. We wondered if the routine postpartum handling undergone by foals, would affect their level of reactivity or the way they express their stress, when older. One single prolonged bout of handling just after birth clearly affected later adult expression of stress reactivity. In social separation associated with novelty, handled, and unhandled horses produced an equal amount of whinnies, showing a similar vocal response to stress. However, both groups differed in their locomotor response to the situations. Early handled foals expressed less of the active forms of locomotion than the control group. Our findings highlight the need of further reflections on long-term effects of routine handlings procedures close to birth.

Orientation of littoral amphipods in two sandy beaches of Brittany (France) with wide tidal excursions

Sandhoppers orient towards the shoreline using a sun compass when they are subject to dry conditions. In this study we analysed the orientation of populations from two sandy beaches with wide tidal excursions (Brittany, France): at Damgan (sea to the South) and at Le Verger (sea to the North). At Le Verger beach Talitrus saltator was found together with Deshayesorchestia deshayesii (former Talorchestia deshayesii). The results of the experiments on sun and landscape orientation showed that the Damgan T. saltator oriented better with ebbing tides than with rising tides, while the Le Verger T. saltator showed the opposite trend as a response to tides. This is probably related to the differing risk of being swept away by tides at the two localities. D. deshayesii was found to be more scattered in orientation than T. saltator, probably because it is a recent colonizer of that beach.

Differential outcomes of unilateral interferences at birth

Behavioural modifications, including modifications of emotional reactivity, can occur following early experience such as handling (manual rubbing). Here, we investigated the effects of unilateral tactile stimulation at an early stage on emotional reactions later on. We handled newborn foals intensively on one side of their body. This early unilateral tactile experience had medium-term effects: the reactions of foals to a human approach, when they were 10 days old, differed according to the side stimulated at birth. Fewer right-handled foals accepted contact with humans, they delayed first contact longer and they evaded approaching humans sooner than did non-handled and left-handled foals. These results raise questions concerning the organization of neonatal care in animals and humans.