A. Lenoir, L. Querard, N. Pondicq, and F. Berton.
Reproduction and dispersal in the ant Cataglyphis cursor (Hymenoptera: Formicidae).
Psyche 95:21-44, 1988.

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REPRODUCTION AND DISPERSAL IN THE ANT
CA TA GLYPHIS CURSOR (HYMENOPTERA, FORMICIDAE) BY A. LENOIR~, L. QUERARD~, N. PONDICQ~ AND F. BERTON* Cataglyphis cursor (Fonscolombe 1846) is a Mediterranean formicine species, living in dry and arid habitats which have sparce vegetation (Cagniant 1976a). It is also found in areas covered with relatively abundant vegetation, for example in Provence near Apt in abandonned lavender fields (Lenoir et al. in prep.) or in meadows of the Catalan coast near Barcelona (Retana, in prep.). Societies are considered to be monogynous and monodomous (Cagniant 1976b, Retana 1986). Elsewhere Cagniant (1973) and Suzzoni and Cag- niant (1975) observed, in the laboratory, that orphan workers of this species are able to reproduce by thelytokous parthenogenesis, which enables the colony to gain a recently inseminated queen. As neither queenless colonies, nor isolated females, have ever been observed in the field, we wished to investigate modes of colony foundation in this species.
All observations were made during July and August from 1983 to 1986 in 3 sites in France: near Apt (Vaucluse-500 m high), near Le Muy (Var-150,200 m), and on the edge of the Etang de Leucate (St-Hippolyte, Pyr-Orientales, sea level). In some of the sites the entrances of the nests were flagged with a numbered label. When necessary workers and sexuals were captured. They were marked with a dot of paint "ch-amique a froid" and released 5 or 10 minutes later. This technique was tested in the laboratory, where marked ants immediately reentered their nest without hostility from their nestmates. Marked individuals did not have a higher mortality rate ILaboratoire d'Ethologie et Sociobiologie, UA CNRS 667 Universitk Paris Nord, av. J. B. Clement, F-93430 VILLETANEUSE, FRANCE. ZLaboratoire d'Ethologie et Psychophysiologie, Facult6 des Sciences, Parc de Grandmont, F-37200 TOURS, FRANCE.
Manuscript received by the editor December IS, 1987. Pnche 95:214 (1988). hup //psyche rinclub orgt95t95-02l.htinl



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(at least over a few weeks). All observations were carried out during the day from 8 to 16 h (Solar Time), which covered all the period of activity of these strictly diurnal ants (Lenoir et al., in prep.). 1. Number of queens per colony
Excavation of a nest is easy because of its predictable structure. Under the superficial chambers is a vertical well, which covers chambers where a great number of workers are packed with brood and the queen (Cagniant 1976b). Sometimes the well begins after a more or less inclined tunnel. In each case the queen was found (except when digging was impossible-for example when the nest was under a large stone). The queen was located at various depths, generally 40 to 80 cm deep in April. She moves up in May when the soil is moist, she goes deeper during drier periods. The exact posi- tion depends on the nature of the substrate (Cagniant 1976a). In sand, for example on the edge of the Etang de Leucate, nests are above the water level, which is at 60 cm. In limestone they are deeper. More than 150 nests were dug up; each contained only one queen. During a short period following swarming, however, colonies may contain several inseminated females and are temporarily polygynous (see below). In May 1986 one colony was found at St-Hippolyte (Pyr-Or.) with 3 queens. This colony was reared in the laboratory, and we observed the rejection of supernumerary queens on the 5th of July. The two rejected queens were dissected and it appeared that they were not inseminated, so they cannot be consid- ered as true queens.
2. Colony size
Fig. 1 represents the number of workers in late April/beginning of May before the first brood appearance. It is known that no brood is present during wintering (Cagniant 1976b, Retana 1986). Estima- tion of colony size is relatively easy. The nest can be excavated during the resting hours when all the ants are in the nest. With the help of a battery-operated vacuum equipment all the workers and brood can be systematically removed and counted. The mean number of workers is 675.5 (SD 440, n = 24, range 34-1590). Cagniant (1976b) found the mean number to be 600 (range 5-1300) and Retana (1986) states that worker number varies from 150 to 1500. C. bicolor colonies have, on average, 2600



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Lenoir, Querard, Pondicq, & Berton- Cataglyphis 23
Fig. 1.
Frequency of number of workers per colony, including data from Cagniant 1980 (34 workers), and from Cagniant 1983 (1 106 workers) N: Number of
colonies NW: Number of Workers.
workers; C. albicans has 700 (Schmid-Hempel 1987). Figure 1 shows that small colonies are not frequent. Isolated females were not found at any time of the year. Cagniant (1980) found only one small colony with 34 workers, but never isolated queens. In ant species which form new colonies with a solitary female (haplometro- sis) it is common to find an isolated queen, or a queen surrounded by a few workers (Wilson 1971). This fact suggests that haplometro- sis is unusual or absent in C. cursor.
3. Behavior of sexuals and mating
The mating period occurs from mid-June until the end of July, depending on the year and the climate. In the Pyrknkes-Orientales flight season is finished at the end of June; in the Luberon (Vau- cluse) at 500 m it ends one month later. These data are in agreement with the observations of Bernard (1968) and Cagniant (1976b). In Barcelona sexuals appear at the end of May and leave the nest in June (Retana 1986). The exit of sexuals occurs between 9 h and 14 h



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24 Psyche [vo~. 95
(ST), which are the warmest hours of the day. Frequently males and females from one nest do not come out simultaneously (also in C. sabulosa (Shalmon 198 1) and C. bicolor (Schmid-Hempel 1987)). Behavior of males before mating
Fonscolombe (1846) observed males running around nest entran- ces. Such behavior can be observed frequently in early summer in the Mediterranean region. When they reach the exit of the nest, the males stop for a few seconds and then fly off. Males are apparently able to fly distances greater than several tens of meters, but we were unable to estimate their exact range. Apparently they do not often come back to their native nest; males captured and marked at the exit of one nest were never seen returning same place (n = 16). When a male arrives within 10-15 cm from a nest entrance, he may stay there motionless for several minutes; he may be attacked by workers. When marked males are recaptured later, recapture occurs near the nest entrance where they were originally captured (12% were seen again; n = 25).
This observation contradicts the suggestions of Cagniant (1976b), who supposed that mating occurs between the members of the same colony. Apparently this must be exceptional: outbreeding appears to be the rule. In the laboratory we did not observe spontaneous matings between siblings whereas it is easy to produce matings by introducing alien males (observed previously by Cagniant, pers. comm.).
Behavior of females before mating
Alate females often come timidly to the exit of the nest before they finally leave. When alate females prepare to leave the nest, workers and males frequently dance around the entrance. Workers are very aggressive towards males and may kill them: this could indicate that they are from a different colony. Females walk around the nest, within a radius of 1 m. Apparently they cannot fly. Are the wings too short, as supposed by Cagniant (1976b)? Wings seem to be normal but it must be measured in comparison with other spe- cies. Santschi (1929) observed one apterous species: C. theryi. If males are present, mating occurs immediately. If several males are present around a female, some slight aggressive behaviour may be noticed between the males. In the absence of males, females climb onto a stone or a twig for a few minutes and then descend. They then begin a "sexual calling" behavior, with the gaster bent under



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19881 Lenoir, Querard, Pondicq, & Berton-Cataglyphis 25 the thorax several times during 2 or 3 min. If no male arrives, they reenter their nest, but frequently males do appear and mate. This female-climbing behavior may be interpreted in two ways. First, a sexual attractant pheromone might be emitted as suggested by the position of the abdomen. Sexual pheromones are known in some ant species (see Discussion). The fact that females do not fly renders use of sexual pheromones an advantage for this species. A second explanation is that the female is more easily seen by the males. It is known that Cataglyphis ants have a well developed visual system and workers orientate by vision during their foraging trips (Wehner et al. 1983). Males may also use vision to locate females. Acoustic communication by wing vibration is improbable because it cannot be used for distanct communication, and has not yet been observed in the sexual behavior of ants.
Mating
In C. cursor mating occurs on the ground (Cagniant 1976b) near the females nest during the hottest hours of the day (9 to 14 h). It lasts from some seconds to one minute. Two positions are possible: the male behind and above the female facing in the same direction, or the male facing in the opposite direction touching the female only by the extremity of the gaster. One male can copulate successively with several females after no more than a one minute intermission. Females may mate successively with one male or with different males. On various occasions in which males and females were present, mating did not occur for unknown reasons. Male behavior after mating
Following copulation, males stay around the nest. During the night they crawl under stones or on twigs, with their heads directed toward the soil. They die rapidly: life span is probably not longer than 2 or 3 days. They are aggressed by C. cursor workers, or killed by predators, essentially spiders. Bernard noted the existence of nocturnal aggregation of C. cursor males (in Grassk 1942). Female behavior after mating
After mating, newly inseminated alate females reenter the nest but sometimes run frenetically around the nest for several minutes. They are helped to reenter the nest by workers. Perhaps the females have difficulty in orienting themselves because it is their first foray into the open. When inseminated, females stay in the nest. These females will soon lose their wings in the nest. During the following days



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apterous females may come out and mate again. They are generally inseminated but dissections have shown that there are exceptions. It is well known in ants that virgin queens lose their wings after some delay if they are not inseminated. During this period we find polyg- ynous nests in the field. Such nests are rare and polygyny lasts only a few days. Supernumerary queens are rejected by workers if bud- ding does not occur rapidly. Ostracized queens leave the nest and die. We dissected 2 of these rejected queens: they were not insemi- nated. Dead queens are also expelled from the nest. Mating in the laboratory
We obtained matings between sexuals of different colonies in the laboratory. The length of mating was variable, from 40 sec. to more than 16 minutes (mean = 333s; n = 9). This may have been related to the low temperature of the laboratory (2Så¡C) These observations are comparable to others in Formica where the mean time is 3.1 min (range 0.5-7.5 min) (Rosengren et al. 1986). The presence of a full spermatheca indicated a successful copulation. In all the observed cases the females reentered their artificial nest. During this period the societies are polygynous with the old queen and newly insemi- nated queens. In the laboratory some colonies kept several queens for a long time (until wintering). Later they again became monogy- nous. The mechanism for the elimination of supernumerary queens is unknown: aggression between queens or aggression of queens by workers? Is the surviving queen the old queen? In our colonies the surviving queen was not the old one (as indicated by individual marking), but additional observations are needed. 4. Foundation of new colonies
Budding was observed twice in the field in 1985, after the period of mating. Workers transported larvae, cocoons and other workers to a new nest. We may suppose that explorers had previously localized unoccupied holes which could be used as a new nest site. Transporting workers made many journeys between the two nests. Moving was directed towards 3 nest sites in the 1st case (Fig. 2) and 4 nest sites in the second case. The mean distance to the new nests was 6.5 m (range 3.2-1 1.3 m).
Traffic lasted for two days. In Fig. 2 shows that nest 2 was aban- doned, and then occupied later by a colony which moved totally from nest 1. Nest 5 was abandoned after 3 weeks and the colony divided in two sister colonies, at least one of which had a new queen.



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19881 Lenoir, Querard, Pondicq, & Berton- Cataglyphis 27 Fig. 2.
Map of a population of C. cursor colonies showing a budding process. Asterisks indicate positions of the nests. A: fission of colony 2 into 3 daughter colonies 3, 4, and 5.
B: second step = nest-moving of colony 1 to the abandoned nest site 2.
In the second observed budding the colony emigratd completely and divided into 4 nests, 2 of which were later abandoned. The two remaining sister nests were dug later, and they comprised 141 and 195 workers each with a new inseminated queen (recognized by a dot of paint). The two colonies were of small size, perhaps because



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28 Psyche [VOI. 95
the mother colony was located at 0.8 m from a big colony with more than 1000 workers. Traffic between the mother and daughter nests was measured for periods of 5 mn during the maximum activity period of the budding day. 6 to 9 workers were transported during 5 mn, which could indicate a population in daughter nests of at least 250-300 workers. Probably some transported workers returned to their mother nest. Division of labor for moving has not been stud- ied: it is not known if the transporters are specialized ants. After budding the new colonies were not very active. It is not known if the old queen survives. In the 4 cases where it was possible to examine this with marked queens the surviving queen was a newly insemi- nated queen, but we cannot make any decisive conclusion with so few observations.
Colony foundation with isolated queens
A few experiments were conducted with newly inseminated queens either isolated (n = 5) or with 4 or 5 workers (n = 4). Isolated females die in a few weeks and rarely lay eggs (also observed by Cagniant, pers. comm.) Females associated with workers can live for several months, and sometimes longer after wintering. Some larvae were observed but they never developed into callow workers (also Cagniant pers. comm.). These data need to be confirmed with larger samples but it seems that isolated foundation does not exist in C. cursor. If possible, it is surely an accessory mode of reproduction of colonies..
A new argument against isolated foundation can be found in the weight of queens and workers. It is generally considered that species with haplometrotic foundation have larger queens relative to the size of their workers (Wheeler 19 10, Sudd 1967, Wilson 197 1). Most monogynous species have large queens that are highly differentiated from the workers (Baroni Urbani 1968). Table 1 shows that found- resses of Lasius niger are 44 times heavier than their nanitic workers. In Liometopum occidentale and L. apiculatum, two Mexi- can Dolichoderinae species founding in isolation, the proportions are respectively 33 and 45. In contrast, in mature colonies of L. niger the queen/ worker ratio is less than 10: workers of mature colonies are 4 times heavier than nanitic workers of young colonies. In Sole- nopsis invicta the first nanitic workers weigh 0.33 mg, the second generation workers 0.6 mg and the workers of mature colonies 0.5 to 1.92 mg (Porter and Tshinkel 1986). By comparison, in small



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19881 Lend, Querard, Pondicq, & Berton- Cataglyphis 29 colonies of C. cursor the female is only 1.8 to 3 times the weight of workers. We never found colonies with nanitic workers. We weighed the workers in a small colony composed of 3 1 workers: they were on average heavier than the overall mean. Perhaps the largest workers, more resistant, are more likely to survive in small colonies issued from budding. This needs to be confirmed with additional small colonies.
The situation is not so simple as in Iridomyrmex humilis, a spe- cies forming a unique giant polydomous nest in the south of France, where young societies do not exist. The ratio Q/ W is 8.28 (Passera and Keller, in prep.). We conclude that a ratio of 30-40 is proof of an independent foundation but a ratio of 7-10 is inconclusive. 5. Intermst Relations
We observed workers leaving a nest and then entering into a neighboring nest. The workers of these nests were marked with one color for each nest, so that traffic at the entrance could be measured. The data presented here were collected on the plateau of Claparkde near Apt (Vaucluse) during July 1983 between 2 nests one meter apart (nest 1 and nest 0). Direct journeys between the two nests were recorded. In most of the passages the workers were not loaded, although they sometimes transported cocoons, a worker or prey. The transporting workers of colony 1 reinforce their society as their traffic is important in direction of colony 0 (Table 2). The data in Table 2 are indicative because only 50% of the observed ants were marked. This means that the real flux of exchanges was probably double. Table 2 shows that colony 1 is more active at the entrance of colony 0. The activity also varies greatly according to days.
These two colonies were excavated at the end of August: in colony 1 we found 750 workers and 1500 in colony 0. In this case it seems that traffic is inversely proportional with the size of the colony. From the 1st to the 5th of August a second set of observa- tions permitted us to quantify the proportion of ants of one nest found at the entrance of another nest. Each alien ant observed at one entrance was marked with a second spot of paint indicating the number of this entrance. In this experimental design each worker is counted only once. 2 new nests appeared during this period: nest 10 at 40 crn from nest 0 and nest 11 at 1.6 m from nest 1.



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Table 1:
Fresh weight (mg) of queens and workers in some ant species. Mean (mini-maxi) k SD, n = number of measures, nanitic workers are weight by 10. 'after Boomsma and Isaaks 1985; 2after Cagniant 1980; 3after Cagniant 1983; dafter Passera and Keller in prep. (comm. pers.).
Lasius Cataglyphis
Liometopum Iridomyrmex
niger cursor
L. occidentale L. apiculatum humilis
YOUNG COLONY
queen
workers
27.4 Alate queens
39.7k0.57 54.3
(25.3-32) 22.0k0.53
(33.6-40.7) n= 1
n=4 n = 412
n= 16
MATURE COLONY
queen
workers




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19881 Lxnoir, Querard, Pondicq, & Berton- Cataglyphis 3 1 Table 2.
Number of alien workers leaving or entering nests 0 or 1 (duration of observations 1 h by periods of 5 mn during the day). Ants from nest 1 at Ants from nest 0 at
Date entrance of nest 0 entrance of nest 1 221 71 83 136 36
23 3 3 3
25 17 65
26 34 44
27 5 5 3 8
28 2 1 12
29 84 12
mean 54.3 30
--
nb workers of colony 1: 750
colony 0: 1500
The two new nests were much less active and nest 11 was closed before the end of the five days observation. Nest 10 closed a few days later and was in fact a secondary nest for colony 0 (when we dug we found superficial galleries connecting 0 and 10). Neverthe- less, it was surprising to observe above-ground cocoon transport between the two nests. Nests 10 and 11 were abandoned after their closing. Some exchanges were also observed between more distant nests (4.4 m apart). In another case cocoon transport was observed between two colonies 60 cm apart (each colony had its own queen). Some transport of prey was also observed here, which could be interpreted as intercolonial robbing. This phenomenon seems to be frequent in some ponerine species, e.g. Ectatornrna tuberculaturn (Lachaud pers. comm.).
These observations can be explained by the mode of foundation of new colonies: it is probable that colonies 1 and 0 are sister colo- nies, given that they keep strong links. The workers probably have a similar colony odor and do not attack each other, which may permit robbing of cocoons or prey. It is more difficult to interpret the late budding trials for nests 10 and 11. When workers occupy a new nest for several days, they transport cocoons. If there is no queen availa- ble, they abandon the provisional nest (84 workers were marked at the entrance to nest 11; when it was excavated we found only 4 workers). This reflects a tendency toward budding to form new societies after the mating season. Other budding trials were observed: one with 4 workers and 5 cocoons, another with 30 workers and a few cocoons, another completely abandoned.



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Table 3.
% of workers of one nest observed at the entrance of another nest. Destination nest Number of
0 1 10 11 workers
0 75.4% 10.6% 14% 0% 236
Source 1 5 93.2 1.8 0 163
nest 10 22.6 11.8 65.6 0 93
11 7.1 38.1 3.6 51.2 84
Additional field experiments confirmed the existence of related- ness between interacting societies. In July 1984, 3 colonies were orphaned and all the workers marked with a dot of paint. They were abandoned the next day either at their old nest, or at a distance of two hundred meters. In the former case we observed numerous transports of workers and brood in direction of neighboring nests, whereas in the latter case no transport occurred (Lenoir and Cagniant 1986). Transports are probably possible if the abandoned workers are closely related to the resident ants. When the colonies are near, they are probably related by budding. We tested this hypothesis at St-Hippolyte (Pyr. Or.) during 1986. When a colony is excavated to remove the queen, although workers are not marked, it is easy to observe transports in direction of neighboring colonies. This phenomenon is possible because immature workers found by foragers in the outside arena are retrieved into the nest. (Nowbahari and Lenoir, MS). Bonavita and Clement (1986) observed the same behavior with Camponotus vagus nurses where foragers retrieve all ants (callows, nurses) into the nest which are not normally there. To experiment on the closure of societies, workers were trans- ferred to the entrance of another society. A worker was captured when leaving its nest, marked and placed near the entrance (less than 5 cm) of an alien nest in a small box. When the ant was calm the box was opened and the behavior of the ant noted for 5 min. Five recipient nests were chosen, the intruders coming from various nests more or less distant (max. 50 m). The results are presented in Table 4.
84% of control workers enter their own nest within the 5 min observation, while only 22.5% of displaced workers entered the for- eign nest. It is not known if these ants were adopted or were later rejected. 4 of them were observed during the following days: they



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Table 4.
Transfer experiments, % of workers entering the nest, n = number of ants tested, x2 = 92.868 (P < .001), x2 for experimental group = 6.595 (NS). Nest Number
controls 1 2 3 4 5
% workers
entering 84 7.5 25 27.5 27.5 25
the nest
behaved normally in their new colony where they seemed to be completely adopted. Some nests are very closed: only 7.5% of ants entered nest 1. Control ants, after marking, seemed to recognize