Petrov I. Z.

English

University of Szeged

SOME REMARKS ON THE FORAGING STRATEGY IN CATAGLYPHIS AENESCENS NYL. СHYMENOPTERA, FORMICIDAE) I. Z. Petrov Petrov, I. Z. (1993): Some remarks on the foraging strategy in Cataglyphis aenescens Nyl. (Hymenoptera, Formicidae). - Tiscia 27, 23-28. Abstract. The frequency of exits and entries, the maximal distance of foraging trips from the nest, as well as the foraging route shape of a marked ant, in the connection with the temperature of sand were observed twice in 1981. The number of exits of the marked ant was similar in both cases (12 and 10 times). The maximal distances were similar in both cases (10 m and 10.6 m). The marked ant spent similar time in the nest between two exits (on the average 20.25 min. and 25.3 min. respectively). There is a difference in the time spent out of the nest (13.94 min. and 21.6 min. respectively). The marked ant shows the site-fidelity, by running in the same direction chosen by the first exit. Key words: ant foraging strategy, diurnal activity, Deliblatska pescara. I. Z. Petrov, Institute of Zoology, Faculty of Biology, University of Belgrade, 16 Studentski trg, 11000 Belgrade, Yugoslavia Introduction This paper continues the series of works on Cataglyphis aenescens Nyl. (formerly called C. cursor Fonsc. or С. c. aenescens Nyl.) (Petrov 1984, 1985, 1986, 1988, 1990; Petrov and Gallé 1986). According to its morphological and ethological characteristics such as: somewhat upward raised gaster, long legs and high running speeds, this species is adapted to arid habitats. Concerning the peculiarities of the habitats which C. aenescens inhabits (semidesert and desert), as well as its importance and role in such habitats, C. aenescens (C. cursor) arose interest of many authors (Cagniant 1973, 1976, 1979, 1980, 1980a, 1984; Dlussky 1962, 1981; Marikovski 1973, 1977; Reznikova 1983; Lenoir 1987; Lenoir et al. 1988; Schmid-Hempel 1987). Since the data on foraging strategy of this species, under poor trophic conditions of semidesert and desert, are scarce (Petrov, 1990), it seemed of interest to continue relevant investigations to illustrate some aspects of the foraging mode of one desert ant species such as C. aenescens. 23 TISCIA 27 Material and methods Investigations on the foraging mode of C. aenescens have been carried out in the locality Cardak (Deliblatska pescara, Serbia), about 70 km northeast of Belgrade, twice in 1981. Both times the investigations of frequency of exits and entries, began with the first exit of the marked ant and lasted 507 minutes each. The ant was marked by using the light colour, in the afternoon of the previous day. The foraging route and the maximal distance from the nest was established by using coloured sticks, which were pined into the sand on each 15-20 cm behind the marked ant, and drawing the routes later. Out of 22 observations of two marked ants from two different nests, it was possible to draw the routes of 13. Result and discussion C. aenescens, like the other Cataglyphis species, is strictly diurnal forager, leaving the nest individually and never undertaking mass foraging. The first observation of July 19, began at 5.30 a.m. and lasted until 2.15 p.m. It can be noticed that the marked ant left the nest 12 times (Tab. 1). The first leaving was at 6.37 a.m., at the temperature of sand of 26 °C, and the last leaving was at 12.31 p.m., when the sand temperature was 57°C. Out of the nest, this ant spent from 2 to 26 minutes. The total out time was 167.3 minutes (13.94 min. on the average) (Tab. 1). This ant spent from 1 to 48 minutes in the nest between two exits, the total nest time was 243 minutes (20.25 min. on the average) (Tab. 1). The maximal distance observed was from 0.1 m to 10 m (the average 3.95 m) (Tab. 1). The marked ant was loaded three times, or 25% of the total exits (Tab. 1). Although this ant used to find certain particles which it began to carry toward the nest, it did not bring them into the nest twice, but lost them and returned unloaded. The second observation of August 4, was carried out between 5.30 a.m. and 2.15 p.m. The marked ant left the nest 10 times. It left the nest the first time at 6.05 a.m. at the sand temperature of 22.5°C. The last leaving was at 1.15 p.m., when the sand temperature was 62.5°C. This ant spent from 1 minute to 2 hours out of the nest. The total out time was 216 minutes (the average 21.6 min.) (Tab. 2). This ant spent from 1 minute to 2 hours in the nest between two exits (the average 25.3 min.). The maximal distance was from 0.1 m to 10.6 m (the average 3.93 m) (Tab. 2). In this observation, the marked ant returned loaded only once. These observations confirm some statements about the related species C. bicolor F. Namely, Harkness (1977) stated that C. bicolor on its foraging trips spent 17 minutes out of the nest on the average, and 8-24 minutes in the nest. Wehner et al. (1983) stated '.hat "the foraging range of a colony can be approximated by a circular area centered around the nest". Their investigations showed that the radius of a circular area within which the ants spend the most of the time doing foraging trips, was 13 m in Greece and 32 m in Tunisia irrespective whether a food item has been found. Their investigations on C. bicolor showed that the number of foraging trips was 10 runs in Greece and only 4 runs in Tunisia. They explained that with the fact that C. bicolor in Greece started its exits earlier in the morning and finished them later in the evening. No. of exit hours (h) out nest time (min) in nest time (min) max.distance (m) sand temp. (°C) If 12 1 1.20 26 2f 650_709 19 1.80 29 3 715_720 5 6 1.70 31 4 8 0 2 - 8 2 1 19 42 9.00 36 5 909_928 19 48 10.00 45 6f 937_945 8 12 7.80 47 7 10 3 2 -10 4 0 8 47 1.40 50 8 И 2 0 . И 4 0 20 48 2.30 56 9 11 4 8 -11 5 8 10 8 3.20 57 10 1 200_1 203 3 2 0.10 56 11 1 2 28 . , 2 30 2 28 2.20 57 1 2 31. 1 2 57 2 12 26 6.80 57 TOTAL 507 min. 167.3 243 47.50 547 x~ - 13.94 20.25 3.95 45.50 Table 1. Frequency of exits and entries, maximal distances, out nest and in nest time of the marked ant (19.7.1981.): food (f.). 24 TISCIA 27 Table 2. Frequency of exits and entries, maximal distances, out nest and in mest time of the marked ant (04.8.1981.): food (f.). No. of exit hours (h) out nest time (min) in nest time (min) m ax.distance (m) sand temp.(°C) 1 6Ö5-6« 20 6.00 22.5 2 6 3 0 - 8 3 0 120 5 10.00 25 3 8 4 7 - 8 4 8 1 14 1 0.10 46 4 8 4 9 - 8 5 0 1 0.20 46.5 5 g50_928 38 0.30 10.60 47 6 940_941 1 28 0.30 51 7f 9 4 7 . , 0 1 5 28 6 6.50 51 8 „ 0 5 . , , 10 5 50 2.80 59 9 11 1 4-11 1 5 1 14 4.00 60 1 315_1 316 120 10 1 3.00 62.5 TOTAL 507 min. 216 253 43.5 470.5 x~ - 21.6 25.3 3.93 47.5 A small percentage of successful foraging trips in our investigations can be explained with poor trophic conditions in habitats which C. aenescens inhabits (semidesert or desert), although Wehner et al. (1983) stated that in their both investigated sites (Greece and Tunisia) about half of the foragers returned with a solid prey (dead arthropod). These investigations in some way, as well as some others, concerning the activity of workers (Petrov 1988), confirm the statement given by Harkness (1977), Dlussky (1981), Wehner et al. (1983) that at any time in a colony, there are not more than a few hundred foragers, which is the smaller part of the colony. In the first observation, the routes of nine exits was established (Fig. 1). It is obvious that although the routes are winding, and the maximal distance is different, the marked ant always foraged in the same direction. The route shapes by its foraging trips are more or less similar (triangular, elongated, eliptic). The first exit was different from the others. Namely, the ant wandered across the bulwark at first, and then suddenly started to run in one direction in which it ran for the rest of its foraging time. In the second observation four routes were established (Fig. 2). On that occassion, the marked 25 TISCIA 27 ant went through one turf of Festuca vaginata on the way from and to the nest. Generally, the route shapes of this ant were almost identical. On the way out, in front of the F. vaginata turf, the marked ant stoped for a while, or turned around itself before it entered the turf. It is obvious that in both cases, the minimal, the maximal and the mean distance were similar. The ants were always going in the same direction chosen by the first exit. Such a behavior of workers confirms the site-fidelity, present in ant species and mentioned by several authors (Rosengren 1977, 1977A; Harkness 1979; Wehner et al· 1983).Making its foraging trips, C. aenescens is hunting over the desert ground at the hottest time of the day. Like all Cataglyphis species, C. aenescens is a scavanger. Its diet consists mainly of dead arthropods (cheafly insects). Small xerophilic snails of the family Cepaeidae were also found to be items of its dietary resources. Plant material and plant saps account for smaller portion of dietary resources of C. aenescens (Petrov, 1990). These investigations stimulate, of course, the question of navigation in this and other individually searching desert ants. That problem has not been investigated by the author up till now. But, Wehner and Räber (1979) and Wehner (1982) stated that the navigational strategies employed by C. bicolor are 1,4 m 3 , 2 m Fig 26 1. Route shape and the maximal distance of the marked ant: nest (n), food (f), lost food (If). TISCIA 27 10 m Ν \ 04.8.1981. F. vaginata 6,5 F. vaginata f ig . 2. Route shape and the maximal distance of the marked ant. nest (n), food (0-27 TISCIA 27 "dead-reckoning (vector navigation by means of celestial compass) and piloting by landmarks". It means that "they rely nearly exclusively on visual cues including sunlight patterns and landmarks panoramas". Conclusions On the basis of present investigations it may be concluded that Cataglyphis aenescens is diurnal individually foraging desert ant. The number of exits and entries were similar in both cases (12 and 10 times). The maximal distances by foraging trips were similar in both cases (10 m and 10.6 m). The average time spent in the nest between two exits of the marked ant was similar (20.25 min. and 25.3 min.). The average time spent out of the nest was different (13.94 min. and 21.6 min.). С. aenescens shows the site-fidelity by doing its foraging trips. References Cagniant, H. (1973): Apasition d'ouvrères à partir d'aefus pondus par des ouvrères chez la Fourmi Cataglyphis cursor Fonscolombe (Hymenoptera, Formicidae). - CA. Acad. Se. 277, D-2197. Cagniant, H. (1976): Cycle Biologique de la Fourmi Cataglyphis cursor Fonscolombe (Hymenoptera, Formicidae). - Vie Milieu 24, C, 277-281. Cagniant, H. (1979): La partenogenese thelytoque et arrenotoque chez la Fourmi Cataglyphis cursor Fonsc. (Hym., Form.). Cycle biologique en elevage des colonies avec reine et des colonies sans reine. - Insect. Soc. 26, 51-60. Cagniant, H. (1980): La partenogenese thelytoque des ouvrières de la Fourmi Cataglyphis cursor Fonscolombe. - Insect. Soc. 27, 157-174. Cagniant, H. (1980a): Etude des stades larvaires, de la lignee des ouvrières des colonies avec reine et des colonies sans reine chez la fourmi Cataglyphis cursor Fonsc. (H., F.). - Bull. Soc. Hist. nat. ¡16, 192-206. Cagniant, H. (1984): Influence de la reine sur l'apparation des sexues et sur la ponte des ouvrières chez la fourmi Cataglyphis cursor Fonscolombe (Hymenoptera, Formicidae). - Bull. Soc. Hist. nat. 120,99-102. Cagniant, G.M. (1962): Muravi sevemovich sklonov talaskogo Altana. - Tnidi Inst. Zool. 18, 177-188. Cagniant G.M. (1981): Muravi pustinj. - Akad. Nauk USSR, Moskovskoe Obscenstvo Ispitatelie prirodi, Sekcija zoologii, Izdateljstvo "Nauka", Moscow. Harkness, R.D. (1977): Quantitative observations on the foraging of nests of an ant (Cataglyphis bicolor F.) in Greece. - Acta Entomologica Jugoslavica 13, 21-33. Harkness, R.D. (1979): Duration and lenghts of foraging paths of Cataglyphis bicolor (F.) (Hym., Formicidae). Entomologist's Monthly Magazine 115, 1-8. Lenoir, A. (1987): Factors determining polyethism in social insects. Expericntia supplcmcntum, 54 - In: Pasteéis, J.M. and Deneubourg, J-L. (eds.): From individual to colective behavior in social insects. Birkhäuser Verlag, Basel, Boston pp. 219-240. Lenoir, Α., Querard, L., Pondicq, N. and Berton, F. (1988): Reproduction and dispersal in the ant Cataglyphis cursor (Hymenoptera, Formicidae). - Psyche 95, 21 -44. Marikovski, P.I. (1973): O muravjah. - Priroda 8, 82-91. Marikovski, P.I. (1977): Muravi roda Cataglyphis ν zapovednike "Pojucaja gora". - In: Poleznie nasekomie Kazastana. Alma Ata. In-ta zool. AN KazSSR, pp. 47-64. Petrov, I. (1984): Gradja grezna i metode preparovanja gnezda pustinjskog mrava Cataglyphis cursor Fonscolombe 1846 (Formicidae, Hymenoptera). - Arh. biol. nauka 36, 3P-4P, Beograd. Petrov, I: (1985): Idioekoloska studija vrste Cataglyphis cursor Fonscolombe (Hymenoptera, Formicidae) na Deliblatskoj pescati. - Magistarski rad, Prirodno-matematicki fakultét, Beograd, pp. 1-96. Petrov, I.Z. (1986): Distribution of species of the genus Cataglyphis Foerster 1850 (Formicidae, Hymenoptera) in Yugoslavia. - Arh. biol. nauka 38, 11-12. Petrov, I.Z. (1988): Distribution of developmental stages and castes in the nest of the Cataglyphis cursor Fonscolombe (Hymenoptera, Formicidae) in Deliblato Sandy Area (Yugoslavia). - Bull. Mus. Hist. nat. 43/44, 139-149. Petrov, I.Z. (1990): Observations on the feeding strategy in the desert ant Cataglyphis cursor Fonscolombe (Hymenoptera, Formicidae). - Arh. biol. nauka 42, 83-89. Petrov, I.Z. and Gallé, L. (1986): Nest distribution of the ant Cataglyphis cursor aenescens (Nyl.) (Hymenoptera, formicidae) in Deliblato Sandy Area (Yugoslavia). -Ekologija 21,135-148. Reznikova, Z.I. (1983): Mezvidovie otnosenia muravev. - AN USSR, Izdateljstvo "Nauka" Sibirskoe otdelenie, Novosibirsk. Rosengren, R. (1977): Foraging strategy of wood ants (Formica rufa group). I. Age polyethism and topographic traditions. -Acta Zoologica Fennica 149, 1-31. Rosengren, R. (1977a): Foraging strategy of wood ants (Formica rufa group). II. Nocturnal orientation and diel periodicity. -Acta Zoologica Fennica 150, 1-30. Schmid-Hempel, P. (1987): Foraging characteristics of the desert ant Cataglyphis. Experientia supplementum, 54. - In: Pasteeis, J.M. and Deneubourg, J-L. (eds.): From individual to colective behavior in social insects. Birkhäuser Verlag, Basel, Boston, pp. 43-62. Wehner, R. (1982): Himmelsnavigation bei Insekten. Neurophisiologie und Verhalten. - Neujahrsbl. Ges. Zürich 184, 1-132. Wehner, R. and Räber, F. (1979): Visual spatial memory in desert ants, Cataglyphis bicolor (Hymenoptera, Formicidae). -Experientia 35, 1569-1571. Wehner, R., Harkness, R.D. and Schmid-Hempel, P. (1983): Foraging strategies in individually Searching Ants Cataglyphis bicolor (Hymenoptera. Formicidae). - Gustav Fuscher Verlag, Stuttgart, New York, pp. 1-79. 28 TISCIA 

Some remarks on the foraging strategy in Cataglyphis aenescens Nyl. (Hymenoptera, Formicidae)

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Some remarks on the foraging strategy in Cataglyphis aenescens Nyl. (Hymenoptera, Formicidae)

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