Journal of Behavior

Original Research Article *Corresponding author Marie-Claire Cammaerts, 27 square du Castel Fleuri, B 1170 Bruxelles, Belgium In a Novel Situation, 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 • 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 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 , 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, 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’ 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. During other time periods, it was provided 90°,so in 60°, four 30°, steps, and the 10° three with thefirst vertical steps lasting plane of10 the min tube and entrance. the last by natural light through a window and varied from 5 to 120 lux An important detail must be underlined here. The same tubes according to the time of the day. The ambient electromagnetic with the same doors were continuously used but they were set, 2. The members of a colony each time, at slightly different places (more to the left, more to are here named nestmates, as is commonly done for social the right, nearer the nest, or farther from the nest). Doing so, .field had an intensity of 2-3 µW/m any potential pheromonal deposit made near the door could

Experimental apparatus and methods apparatus presentations. After the last step (lasting 30 min), thenot ants’ influence sugar thewater ants’ supply behavior was removed, in the course and to ofexamine subsequent if the Preliminary comments: We set ants from two colonies in ants could effectively learn a hitherto never exhibited behavior, front of three never previously encountered situations. Since it another experiment was conducted the day after. For this next experiment, the double door of each sugar water tube was nearly either when they had not yet seen how to proceed or when shut: each side made an angle of only 2°-5° with the plane of the theywas firsthad observationseen how. We for thus us, wedid could not record not predict any numerical their behavior data tube entrance. The door was to be partly but not fully shut so that (numbers, times, locomotion). We only observed and precisely the ants perceived that sugar water was available behind the door. described the ants’ behavior before and after they saw how to However, the door must be shut enough to be an obstacle for the proceed. The obtained qualitative results will allow researchers ants, i.e., the opening must be too narrow to allow easy passage out of the tube with an enlarged gaster. The last experimental to plan new experiments on the subject by defining appropriate J Behav 2(2): 1011 (2017) 2/8 Cammaerts (2017) Email: [email protected] step lasted 30 minutes, after which the experiment ended and placing them on the area laying in front of these entrances, then the ants were fed as usual, having again free access to their sugar setting cotton barriers (with no opening or a large or a small one: water supply. behavior in the four following situations. First, the nest entrances Six hours later, the ants were still collecting the provided weresee above) fully shutin the with nest thin entrance, cotton andbarriers, finally i.e., observing without anythe ants’path sugar water. Indeed, new callows had emerged in the meantime, through them, and the observation lasted 20 min. Second, the and we know that they imperatively need sugar water for their nest entrances were partly shut with cotton barriers presenting survival [18]. Consequently, the ants could no longer be deprived a large notch at one place along their rim (= the solution); this of their sugar water supply. Therefore, the following experiment experimental step also lasted 20 min. Third, the nest entrances no longer used sugar water as a reward, but the inside of the nest, were again fully shut with the cotton barriers, and the observation to test the ants’ ability to learn to use a novel technique. lasted 20 min. Fourth, the nest entrances were shut with cotton barriers with a very small notch in their rim, and this last step Removing a thin cotton barrier to enter the nest: The nest lasted 10 minutes. Thereafter, the experiment ended; all the entrances were shut with a very thin layer (less than 1 mm) of barriers were removed and the ants again had free access to their pure cotton. This barrier shut the entrance entirely, or presented nest inside. a notch large enough to allow ants to enter their nest, or had a very small notch allowing only one ant at a time to enter its nest RESULTS entrances are shown in Fig. 1C. Each notch was made by slightly Preliminary comments pushingwith difficulty. the cotton The barrierthree kinds from itsof cottonrim towards barrier its set center. in the nest As described in the ‘Materials and Methods’ section, we could The experiment consisted of successively removing (three not set up any variables to adequately assess ant behavior we times, see below) a few ants present at the nest entrances, did not know. The results are only qualitative. The ants’ behavior A considered as the control; the ants’ behavior in the same situation butin the after never having encountered seen how to situations proceed (= for the the “solution”) first time each could time be was the test event.

Learning to mix solid sugar and pure water

By themselves, the ants could not solve the problem (a,d). After having seen how to proceed (b,e), they took some water then sugar, or some sugar then water, and (Fig. 2Aa), the ants could not mix solid sugar and pure water. They transported sugared water to the nest(c,f). See Fig. 2A. movedIn presence nervously of around the experimental the solid sugar, apparatus came onto for theit, but first did time not B bring some of it to the nest. They also came onto the pure water and drank some of it during a very short time. However, they did not return to the nest or returned to it without depositing a trail. After that, as soon as we showed the ‘solution’ to the ants (a piece of solid sugar wet with water), the ants came to drink the sugared water (Fig. 2Ab). They returned to the nest and gave the Experimental apparatus build for learning ants to pull on at least one side of a collected sugar water to nestmates. The ‘solution’ was removed double door which shut the entrance of the tube containing the sugar water supply.

afterThereafter, fifteen minutes. when the ants were in presence of solid sugar and pure water separately set at 1 cm distance from one another, they The apparatus was presented with the door shut (the ants could not open the door), came near these compounds, moved frenetically around them, then opened and progressively shut again. The ants entered the tube, and when the often stopped, and moved their antennae, and this lasted 40 min for colony A and 20 min for colony B. Then, a few ants suddenly opening C was very narrow, they pushed on a side of the door. See fig. 2B. (this was obvious) either drank some water then ran onto the sugar, stayed there one or two minutes obviously wetting the sugar and taking some of the wet sugar, or came onto the sugar for a few minutes then ran onto the water and stayed there one or two minutes, clearly sugaring the water then drinking some of this sugared water. In each of these two cases, the ants, the Confronted to a cotton barrier shutting their nest enterance, the ant could not enter gaster of which was somewhat enlarged, walked towards the the nest. After having experienced a large opening in the barrier, when confronted to a very small opening, the ants moved through this narrow path and pushed on the nest, touching the ground with the tip of their gaster, depositing cotton for enlarging the opening. See Fig 2C.

Figure 1. Experimental designs and steps of the protocols used to examine whether sequence of behavior is shown in Fig. 2Ac, d, e. Other ants came ants could learn a novel technique. (A) mixing solid sugar and water; (B) opening a theonto species’ the provided trail pheromone, food and andbehaved finally similarly. entered theirThe nest.ants thusThis double door; (C) removing a cotton barrier. learned a never exhibited behavior, presenting it after a latency

J Behav 2(2): 1011 (2017) 3/8 Cammaerts (2017) Email: [email protected] period of approximately 40 min + 20 min / 2 = 30 min. Could they the ants often slightly pushed on the door from the inside of the ameliorate their response and acquire the ‘new’ behavior more entrance, what enlarged a little the opening of the door. The ants’ rapidly in the course of a second, similar experiment? natural behavior is thus not to pull on something but preferably to push it, except when they can easily grip it. With an angle of Eighteen hours after the removal of the provided food, in a 10° between each side of the double door and the plane of the fourth step, solid sugar and pure water were again presented nest entrance (Fig. 2Bf), the ants’ behavior (described below) to the ants for 6 hours. Once more, the ants could not collect any food (wet sugar or sugared water) but moved frenetically presented only by very few old ants. The experimental apparatus all around the two provided elements. We again gave them the wasresembled kept in the place previous for 30 min.one butSome took ants a camelonger in time front and of it,was moved first ‘solution’ (i.e., a piece of solid sugar with pure water on it) for there for a time, and then suddenly, after approximately 2 min, went between the two sides of the door and pushed one side of took sugar water and went back to their nest. Thereafter, we the door from the inside. They could thus go on and enter the againfifteen presented minutes. toThe the ants ants soon solid came sugar onto and waterthis consumable at 2 cm distance food, tube, move to the sugar water supply, and take some sugar water. While going out of the tube, they often again pushed on the door from the sugar to the water and all around these two elements for in order to make their displacement easier. After one or two approximatelyfrom one another. 15 Themin antsin colony were firstA and perturbed, 5 min in andcolony they B. moved Then, ants behaved in such a way, the other ants moving in the vicinity suddenly (this was again obvious), as previously, a few ants came behaved similarly, and the collection of sugar water could occur either onto the sugar for a time then onto the water, or onto the nearly as usual. Since the delay in correctly reacting decreased (2 water then onto the sugar for a time, and each time, their gaster min vs having enlarged, they then went back to the nest depositing a process of learning to open the door. trail. The ants thus found the ‘solution’ in a shorter time than 25 min; χ² = 0.014, df = 1, P = 0.90), the ants were in the The following day, knowing now that ants preferentially push difference between the duration of the two latency periods (30 on something instead of pulling it, we presented the experimental during the first assay (mean 15 min + 5 min / 2 = 10 min). The apparatus with the two sides of the door making a very small angle with repeated experiences, the ants would acquire the behavior (less than 10°) with the plane of the entrance, which was thus not ofmin collecting vs 10 min) the was two significant compounds (χ² one = 4.32, after df the = 1, other P < 0.05). (a hitherto Thus, entirely shut. It was a surprise to see a few ants coming in front never exhibited behavior), obtaining a consumable food, i.e., a of the door, moving there for a short time, and then suddenly, in food they can bring back to their nestmates. approximately 1 min, inserting their head and forelegs through the opening, pushing towards the outside on one side of the door, Pulling on a double door to reach the sugar water supply and entering the tube. The delay in reaction was still shorter (1 min vs The six steps of the experiment are shown in Fig. 2Ba- admit that a few ants were really in the process of learning how f. In front of a closed entrance, the ants came in front of it and to manage 5 min; a double χ² = 0.38, door df very = 1, slightly 0.50 < Popened < 0.70). to Weenter could their not sugar but walked nervously in front of it, on it, and above it. They probably water feeder. recognized their usual feeder tube and tried to enter it. However, they never pulled on any side of the door (Fig. 2Ba). In contrast, Removing a thin cotton barrier to provide a way to the nest they had a tendency to push the door, which could not open it. Progressively, the ants stopped trying to reach the sugar water In front of their nest entrance entirely shut with a thin layer supply, and after 30 min, very few were still in the vicinity of the of cotton, the ants were very perturbed and moved erratically in experimental apparatus. At that time, we presented to the ants the front of the barrier, on it and above it (Fig. 2Ca). They gripped the apparatus with the door largely opened (= the solution, Fig. 2Bb). cotton, obviously tried to remove it, and being unable to do so The ants came to the now accessible feeder and unexpectedly became more and more nervous over time. After some time, the moved around it for approximately 12 min, on the door, behind ants located inside the nest also became perturbed, which may it, above it, and in front of it. They even stopped at the entrance, have been due to the ants located outside emitting pheromones between the two parts of the door. This may be due to visual and and trying to remove the cotton barrier. olfactory changes in the usual sugar water supply tube. Finally, they entered the tube, again stopped there, looked all around, moved After 20 min, we gave the ‘solution’ to the ants: we partly slowly, and ultimately collected some sugar water. The door was opened the cotton barrier, pushing on it with forceps from its then progressively shut (see the experimental methods). The ants rim towards its center. The ants rapidly discovered the free came to drink the sugar water without any problem when the two path towards their nest and moved, a little cautiously, inside of sides of the door made an angle of 90° (Fig. 2Bc) or 60° (Fig. 2Bd) the nest (Fig. 2Cb became nearly as usual. this angle equaled 60°: they moved all around the door, above it, ). The ants’ traffic through the nest entrance with the tube entrance. They presented some difficulties when Twenty minutes later, when several ants were again removed at an angle of 30°, the ants’ behavior was very interesting (Fig. from their nest and the nest entrance was completely shut by 2Beand ).finally, They movedafter 5 amin, few entered minutes the in fronttube. ofWith the thedoor, door sometimes opened a cotton barrier, the ants were again perturbed, though less slowly entered the tube and drank some sugar water. Either after the barrier; they very often cleaned their antennae, which is havingpresented entered tremors, the tube moved or after their having antennae drunk rapidly, some sugar and finally,water, athan displacement during the behavior, first experiment. moved onto They the again barrier, tried gripped to remove the

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A

a b

c d e B

a b c

d e f C

a b c

Figure 2. Some views of the experiments. (A) mixing solid sugar and water. (a) the two elements presented separately, not collected by ants; (b) sugar wet with water; ants collected the forming sugar water; (c,d,e) after this experience, ants collected the two elements successively and brought sugar water to the nest, their gaster having enlarged. (B) opening a double door: (a) the ants could not open the door, (b,c,d) they easily went through a partly opened door; (e,f) they then could go through a slightly opened door C) removing a cotton barrier plugging the nest entrance; (a) ants could not remove such a barrier, (b) they used a provided free path through the barrier, (c) they could then enlarge a very narrow path for entering their nest. with difficulty and enlarge the opening by pushing on a side of the door. (

J Behav 2(2): 1011 (2017) 5/8 Cammaerts (2017) Email: [email protected] cotton and pulled it or pushed on it but were again unable to may occur in the course of their life.

Fourth, the ants could learn to use a new technique and efficientlyAfter that,create we a freeagain path gave through ‘the it.solution’ to the ants, but perform a task they had never done but only according to their incompletely: we pushed the cotton a little at one place, from its own anatomy, morphology and physiology. They did not transport rim towards its center, providing a very narrow free path through solid sugar onto the pure water to mix the two elements; they it towards the inside of the nest. The ants inspected the given path; mixed them in their mouth, removing one compound, walking up then, in a very short time, one of them slowly used it, enlarged to the second one and removing both. They did not pull a side of it, and succeeded in entering the nest (Fig. 2Cc a double door; they went slightly beyond the door and pushed doing so took some time, approximately 12 min, to accomplish on one side towards the outside to enlarge the entrance. They the task. Thereafter, they did so more rapidly, in approximately). The first ants 1 did not pull the cotton barrier to provide a free way through it but pushed on it to enlarge a narrow free way. Let us remark that dogs also push on doors to open them when they know that min, which was a significantly shorter time period (χ² = 4.26, df these doors can be opened. To come back to ants, of course, they nearly= 1, 0.02 as < rapid P < 0.05). as usual. The freeAll the path ants having removed been fromenlarged the nestby more had applied the novel method not only according to their morphology and more ants pushing on the cotton, the ants’ traffic became and physiology but also according to their limited cognitive abilities. In other words, even if they are apparently able to learn reenteredDuring it eachin five of minutes. the three above-related experiments, we novel behaviors, they are very probably unable to learn very observed that as soon as the ants discovered the ‘way to do’, they sophisticated ones requiring large memory. They may also be hesitated for a very short time, and after that, they suddenly used unable to improvise or to innovate and must learn something new thanks to conditioning and/or imitation. and again normally active. a kind of new technique efficiently, being no longer perturbed Concerning the cognition underlying the presently DISCUSSION approached subject, there exist three levels: 1) being able to learn a cue, a site, a time, etc.; 2) being able to learn new methods or the Three different experiments enabled us to show that ants are use of tools; and 3) being able to improvise a new technique or to able to learn to use a new ‘way to do’ never encountered before, use tools de novo to act as they never did before, progressively through operant many invertebrates and vertebrates; the second level is scarcely conditioning (being rewarded when correctly using the new attained by invertebrates by oneself. but Briefly, often thepresented first level by is vertebrates; attained by techniques) and by imitation (being in presence of the new ‘way and the last step appears not to be sensu stricto presented by to do’ at an appropriate moment). All occurred in the same way invertebrates and attained only by a few vertebrates. In detail, as in any conditioning or learning process: a latency period, then many examples can be found in [23]. 1) Learning by invertebrates 24] and by vertebrates such as and (rats, dogs, monkeys) some learning that increased over time, and a final ‘score’, which [such25] is as currently cockroaches, universally crickets, admitted flies, bees,[23 and and references ants [ therein]. neverFirst, equaled on 100%.the basis This findingof the requires ants’ somemovements, remarks. erratic 2) Learning to use tools by vertebrates is also an accepted concept, according to the performance of trained dogs, elephants, dolphins, horses, and monkeys among others as well as to some entrancedisplacement, is a more assays perturbing for finding event the than solution being deprived and rapidness of sugar in 25 for instance]. Learning to use tools by waterfinding (in the the solution, presence it appeared of meat food).that being This deprivedshows that of antsthe nest are invertebrates has only been recently examined [13,14,26]. 3) As true eusocial insects. forfield spontaneous observations use [ of sensu stricto tools, it is the prerogative of highly evolved vertebrates such as monkeys [27,28]. What is considered ‘using tools’ by insects is not strictly such a behavior, researchers on social Hymenoptera, such as Alem et al [13] and the kind of tool they use being not a sensu stricto tool, but a kind of KarathSecond, [14] (see our the finding introduction is in agreement section). It with is also those in agreement of other ‘proto tool’ [Cammaerts, in preparation]. Tool use requires a high with ants’ adaptation to changes in their environment, with the level of cognition, and it is presented suddenly, spontaneously, by fact that ants can enlarge their behavioral repertory [19,20]. one individual, without any imitation or previous rewarding in This also leads to the same deduction as the recent discovery of a ‘eureka moment’. On the basis of the current knowledge of the bumblebees’ ability to perform, progressively, more and more subject, ants do not strictly use tools, but at least some species complex tasks [21] as well as to push a ball into a hole to obtain seem to be able to learn to apply a novel technique, exhibiting a sugar food [https://www.theguardian.com › Science › new behavior and ameliorating a previous method or behavior. behavior or www.popsci.com/brainy-bumblebees-can-push- balls-into-goal; 22]. CONCLUSION

Third, all the ants observed using a new method, a new ‘way to Confronted with separated solid sugar and pure water, do’, were rather old. It is not impossible that this ability (learning the ants could not bring sugar water to the nest. After having a new method) could be attained only after the ants had learned tasted solid sugar wet with water, then confronted again with all their social behavioral repertory and the social tasks they are pure sugar and water, they successively collected each of these expected to do and had already experienced several events that two elements and brought sugar water to the nest. In front of a

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double door shutting the entrance of their sugar water supply, 10. Cammaerts MC. Sensu stricto individual conditioning, and imitation, the ants could not access their sugar food. After having seen such in the ant Myrmica sabuleti (Hymenoptera, Formicidae). Ann. Soc. En- a door open and then progressively shut, when again in front of tomol. France. 2013; 49: 402-412. a double door nearly shut, they partly went through the opening, 11. Cammaerts MC, Cammaerts R. Are ants (Hymenoptera, Formicidae) pushed on a side towards the outside, and entered the tube capable of self recognition? Journal of Sciences. 2015; 5: 521-532. containing their sugar water supply. Confronted with a cotton barrier shutting their nest entrance, the ants could not enter 12. Cammaerts MC. Ants’ ability in solving simple problems. Int. J Biology. their nest. After having seen a large opening then a very narrow 2017; 9 (3): 26-37. opening in the barrier, the ants could enlarge the small opening 13. Alem S, Perry CJ, Zhu X, Loukola OJ, ingraham T, Sovik E, Chittka L. by pushing on the cotton and enter the nest. Ants can thus Associative mechanisms allow for social learning and cultural trans- learn never previously presented behaviors and learn to apply mission of sting pulling in an . PLoS Biology. 2016; 14(10): e new techniques or methods through operant conditioning and 1002564. imitation, although spontaneously they cannot improvise a novel 14. Karath K. Ants craft tiny sponges to dip into honey and carry it at technique. Such learning may be attained only by old workers, home. Animal Behaviour. 2016.

morphology, physiology and cognitive abilities. 15. Cammaerts MC, Rachidi Z, Beke S, Essaadi Y. Use of olfactory and vi- which then present a novel behavior according to their specific sual cues for traveling by the ant Myrmica ruginodis (Hymenoptera, ACKNOWLEDGEMENT Formicidae). Myrmecol News. 2012; 16: 45-55. 16. Cammaerts MC, Nemeghaire S. Why do workers of Myrmica ruginodis We sincerely thank three anonymous referees whose (Hymenoptera, Formicidae) navigate by relying mainly on their vi- comments allowed us improving our paper. sion? Bull Soc. R. Ent. Belg. 2012; 148: 42-52.

DISCLOSURE 17. Cammaerts MC. The visual perception of the ant Myrmica ruginodis (Hymenoptera – Formicidae). Biologia. 2012; 67: 1165-1174.

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J Behav 2(2): 1011 (2017) 7/8 Cammaerts (2017) Email: [email protected]

About the Corresponding Author

Dr. Marie-Claire Cammaerts

Summary of background: Current research focus:

I work on ants since 1969, studying essentially their ethology and their • We have studied the effects of statins and of a natural product physiology. I have examined their communication, recruitment strategies, used for caring of persons suffering from hypercholesterolemia. The areas marking, navigation systems, visual perception, conditioning latter is better for the health. We have also studied the effects of the abilities, among others. I have also studied the ontogenesis of some of largely used analgesic paracetamol, and are presently examining their cognitive capabilities. More recently, I used ants as biological those of a natural analgesic (an extract of curcuma). models for examining the effects of substances (drugs, food additives …) • We have just finished to examine the potential use of tools by ants consumed by humans. Until now, I could reveal the adverse effects of 24 and their ability in learning to do so. We concluded that they cannot such substances. Even if making pharmaceutical works, I go on studying do so. the ants at an ethological and a physiological point of view. • The ants' potential instinctive perception of what is good or harmful to their health. Permanent e-mail address: [email protected] • The impact on aquatic invertebrates of hormones nowadays present in natural water (using chironomes as models).

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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

J Behav 2(2): 1011 (2017) 8/8