In a Novel Situation, Ants Can Learn to React As Never Before - a Preliminary Study
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Journal of Behavior Original Research Article *Corresponding author Marie-Claire Cammaerts, 27 square du Castel Fleuri, B 1170 Bruxelles, Belgium In a Novel Situation, Ants can Tel: +32-322-673-4969 Email: [email protected] Submitted: 04 May 2017 Learn to React as Never Before Accepted: 19 July 2017 Published: 18 August 2017 - a Preliminary Study Copyright: © 2017 Cammaerts OPEN ACCESS Marie-Claire Cammaerts* University of Brussels, Brussels, Belgium Keywords • Cognition • Memory • Conditioning • Myrmica ruginodis • Food collection Abstract It has been known for a long time that ants can acquire behavioral reactions by conditioning and by imitation. The aim of the present work was to examine if they could, through such learning processes, acquire never previously exhibited behavior or learn to use new methods. Myrmica ruginodis workers were successively confronted with solid sugar and water set apart, a double door shutting their sugar water tube entrance, or a thin cotton barrier plugging their nest entrance. Each time, they could not find an appropriate method to solve the problem. They were then presented with the ‘solution’, i.e., the sugar wetted, the double door slightly opened, and the cotton barrier partly removed. Thereafter, when again confronted with the initial situation, old ants could act appropriately to solve the problem. Ants can thus learn by conditioning and by imitation and can acquire through these processes novel methods or behavioral acts even if they are unable to innovate spontaneously by themselves, to improvise, or to behave correctly in an unknown situation. INTRODUCTION if they could learn behaviors not included in their repertory and never exhibited, such as the use of a novel technique. Ants are among the most evolved eusocial insects in their morphology, physiology, social organization and behavior [1]. Progressive learning of tool use has been discovered in They have a unique resting position of their mouth parts [2] bumblebees. These social insects scarcely can pull a string to get and numerous glands emitting pheromones [3]. Their highly sugar water, but they can learn this behavior over a rather long organized societies have a strong division of labor, age-based time if trained to perform it by operant conditioning in a stepwise polyethism and social regulation [4]. Their largely extended manner. Naïve bumblebees can also acquire this behavior simply behavioral repertory includes nest building, care for brood, by seeing nestmates exhibiting it [13]. Some ants have been sophisticated nest building, and chemical marking of the inside shown to be able to ameliorate a technique. When workers of of the nest, nest entrances, nest surroundings and the foraging Aphaenogaster subterranae and A. senilis are provided with a area [5]. Ants generally use an alarm signal, a trail pheromone, honey solution and different materials allowing collection of this and a recruitment signal [4]. They navigate using memorized cues [5,6 4,5], and they clean they select the best ones [14]. their nests and manage cemeteries [7]. In fact, they perform honey, first, they use all the materials, and then, progressively, numerous]; complexthey efficiently tasks thatrecruit result nestmates from individual [ simple acts In summary, others and our research on ants’ behavior has and remarkable coordination between nestmates. Young ants brought us to the presumption that ants may potentially be able learn these abilities [8], and until they become old, ants can learn to learn new behavioral methods [9,10,12,14,15,16], and we several new elements (cues, trajectories, locations of food sites, intended to perform experiments to examine this presumption, times of available food) essentially through operant conditioning working on a well-studied ant species, Myrmica ruginodis [9]. They can also imitate nestmates [10] and are able to recognize Nylander 1846 [17]. themselves in a mirror [11]. Recently, we approached the extent of their cognitive abilities. Ants can solve several problems (for Three kinds of experiments were attempted, the ants being instance, walking around a barrier, preferentially walking on a each time obliged to perform a task they had never performed smooth substrate, establishing a single way, or pushing a door) before, i.e., to use a novel technique. Each time, if the ants acting each time according to their innate behavioral repertory appeared to be unable to perform the novel task, we tried to [12]. Since ants are able to learn new elements and/or behaviors teach them to perform it, allowing them to go through operant through conditioning and imitation, it is not nonsense to wonder conditioning (i.e., rewarding them) and to imitate (i.e., showing Cite this article: Cammaerts MC (2017) In a Novel Situation, Ants can Learn to React as Never Before - a Preliminary Study. J Behav 2(2): 1011 Cammaerts (2017) Email: [email protected] them the ‘solution’). We did not know what the ants’ reaction variables for assessing, at least partly, the ants’ behavior. could be, and therefore, we could not set up variables assessing such unknown reactions. We focused on precise description of Learning to mix solid sugar and pure water: The material the ants’ behavior, and informed of what may occur, we plan to consisted of glass cover slips (2 cm x 2 cm), solid sugar (pearl record data in the course of future works on the subject. sugar), and tap water. The experiment occurred in six steps after the ants had been deprived of their usual sugar supply for MATERIALS AND METHODS 12 hours. This is schematized in Fig. 1A water and solid sugar were separately presented to the ants on Collection and maintenance of ants cover slips set at 6 cm from one another (. Fig.In the 1Aa first). Twenty-four step, pure hours later, in a second step, a piece of solid sugar covered with a The experiments used two colonies of M. ruginodis collected in droplet of pure water was presented, as a ‘solution’, on a cover slip the Aise Valley (Ardenne, Belgium) at the beginning of June 2016. between the two elements previously deposited and still in place The experiments were conducted in winter 2017. The colonies (Fig. 1Ab). Three hours later, all these elements were removed, contained approximately 500 workers, 1 - 2 queens and brood. and the ants received two pieces of solid sugar on a cover slip and a droplet of water on another cover slip (Fig. 1Ac). This third step lasted 45 min, and six hours later, all the elements were removed. antsThey from were the maintained water. New in the nest laboratory tubes were in artificialprovided nests as necessary made of The following day (i.e., 18 hours later), in a fourth step, pieces so2 - 3that glass each tubes colony half-filled relocated with atwater, its convenience. a cotton plug separatingThe inhabited the of solid sugar and pure water were again presented separately nest tubes never dried or moistened. The nest tubes of each colony on two different cover slips, for 6 hours (Fig. 1Ad). After that, were deposited in a tray (34 cm x 23 cm x 4 cm), the internal sides of which were slightly covered with talc to prevent the ants from to the ants for 15 min: they received solid sugar wet with water escaping. The youngest ants stayed inside the nest, the middle- onin aa fifth cover step, glass ‘the set solution’ between of the the two problem cover was glasses again deposited presented 6 aged workers moved inside the nest as well as in the trays, and hours earlier (Fig. 1Ae). Fifteen minutes later, all the deposited the oldest ants essentially foraged outside. The trays served as elements were removed, and in a sixth step, the ants separately foraging areas; foods as well as experimental apparatus were received two pieces of solid sugar and some pure water on two delivered in them. For each colony, approximately 25 ants walked distinct cover glasses 1 cm distant from one another (Fig. 1Af). in the trays and could interact with the apparatus. An aqueous The experiment ended 35 minutes later. solution of sugar (30%) was provided ad libitum in a small glass tube (diameter: 1.5 cm, length: 7 cm) plugged with cotton, and Pulling on a double door to reach the sugar water pieces of Tenebrio molitor larvae (Linnaeus, 1758) were provided supply: The experimental material, the construction of as meat three times a week on a glass slide. The ants were not the experimental apparatus, and the successive steps of the starved when experimented on. However, one day prior to the experiment are shown in Fig. 1B. The tube containing the ants’ two experiments using the sugar water supply, the ants were sugar water supply was shut with a double door made of white deprived of that food but not of meat. During the experimental paper (80 gm-2) and tied to the tube using Scotch tape®. The period, the queens’ egg laying and the larva development were hinge of each side of the door was handled many times so that both weak. At the end of this period, emergences occurred. The the door could be opened very easily. Such shut tubes were workers essentially collected sugar water, and this was the ideal presented to the ants for 30 min. Then, the double doors were situation for setting experimental apparatus in front of the sugar widely opened, the tubes being still in place (= the solution). After water supply and the nest entrances. The laboratory temperature 15 min, we progressively shut the double door of each tube, doing was maintained at 18°C - 22°C with relative humidity near 80%. The lighting had an intensity of 330 lux while caring for the ants 30 min. Each side of each double door made successive angles of and testing them.