Desert Ant Cataglyphis Research Articles

Dufour’s Gland Composition in the Desert Ant Cataglyphis: Species Specificity and Population Differences

Abstract Dufour’s gland secretion of several species of the desert ant Cataglyphis from different geographical localities was analyzed. The secretions constituted mostly of alkanes ranging from undecane to nonadecane. Species specificity is expressed as variations in the major component as well as the relative intensities of the additional constituents. Phylogenetically related species that are allopatric exhibited similar secretory composition whereas their sympatric counterparts had disparate composition, suggesting that character displacement occurred. Analyses of colonies of C. cursor from different localities also showed divergence in their glandular composition.

Polarized skylight orientation in the desert antCataglyphis

The desert antCataglyphis bicolor is able to use the pattern of polarized light in the sky as compass. By confronting the ant to single spots of artificially and naturally polarized light it is shown howCataglyphis uses the polarization pattern. When exposed to a horizontal e-vector,Cataglyphis was always oriented correctly. Orientation errors occurred, however, when other e-vector directions were presented. This indicates that the e-vector positions assumed by the ant do not coincide with the e-vector positions actually realized in the sky. From this it is concluded thatCataglyphis has no detailed knowledge of the actual azimuthal positions of the e-vectors. Instead, it is relying on a simplified celestial map of the polarization patterns in the sky (Fig. 7). Usually, the ant did not confuse celestial spots with identical e-vector directions. Even at sunset when the polarization pattern is completely ambiguous, correct orientation occurred. This suggests that the ant uses additional celestial cues such as the degree of polarization, the color or the intensity to find its way home when the sun is obscured.

Mandibular Gland Secretions as Alarm Pheromones in Two Species of the Desert Ant Cataglyphis

Abstract Mandibular gland secretion of two Cataglyphis species were chemically analyzed by combined gas chromatography mass spectrometry. The exudates produced by C. bombycina consisted of citronellol and geraniol while that of C. nigra contained only geraniol. The reaction of both species to the glandular secretions was alarm and recruitment. While the reaction of C. bombycina was strong, that of C. nigra was relatively mild.

Does interocular transfer occur in visual navigation by ants?

If an animal that learns to respond to a visual stimulus presented to only one eye can continue to respond accurately when the stimulus is presented to the other eye, it is said to exhibit interocular transfer (IOT). IOT has been studied extensively in many groups of vertebrates1–11, but there is only one conclusive report of IOT in an invertebrate (Octopus)12. Here we demonstrate that an insect, the desert ant Cataglyphis, exhibits IOT when it navigates by the pattern of polarized light in the sky, but shows no IOT when it uses landmarks for orientation. This marked difference in behavioural performance may help to elucidate the neural strategies adopted by insects when using celestial (polarization) and terrestrial cues for navigation.

Ocelli: A Celestial Compass in the Desert Ant Cataglyphis

In addition to multifaceted lateral compound eyes, most insects possess three frontal eyes called ocelli. Each ocellus has a single lens, as does the vertebrate eye. The ocelli of some flying insects, locusts and dragonflies, have been shown to function as horizon detectors involved in the visual stabilization of course. In a walking insect, the desert ant Cataglyphis, it is now shown that the ocelli can read compass information from the blue sky. When the ant's compound eyes are occluded and both sun and landmarks are obscured, the ocelli, using the pattern of polarized light in the sky as a compass cue, help in guiding the ant back home.

Golgi-Em-study of first and second order neurons in the visual system ofCataglyphis bicolor Fabricius (Hymenoptera, Formicidae)

1) Comparable to the bee, but in contrast to the majority of ants, the desert antCataglyphis bicolor has been shown to exhibit a highly developed repertoire of visually guided behavioural responses. This paper deals with the anatomy and fine structure of the peripheral visual pathway of this ant. In the first visual neuropile, the lamina, first and second order neurons are classified by applying Golgi methods adapted for electron microscopy. Synaptic connections within the lamina are described and discussed. The results are summarised in developing a three-dimensional model of the ant's lamina (Fig. 17). 2) Eachretinula within the central eye region is composed of four large (nos. 2, 4, 6 and 8) and four small retinular cells (nos. 1, 3, 5 and 7) and a basal ninth cell. Visual cells nos. 2, 3, 4, 6, 7, and 8 form short unbranched axons (Rs), which terminate within the lamina. The visual cells nos. 1 and 5 (Rl), as well as the basal cell no. 9, show arborisations in the lamina, but terminate in the second visual neuropile, the medulla. Within the lamina all nine retinular cell axons, originating from one retinula, form a cartridge within which they interact with the second order neurons, the monopolar cells. Collaterals of second order neurons and side branches of retinular cell axons form local neuronal circuits. 3) Five types ofmonopolar cells have been classified by means of their dendritic fields within the lamina and the medulla (L1a, b, c, L2 and L4). They relay the retinular cells with higher order neurons within the medulla. In the distal layer of the lamina (stratum A) the spreads of the monopolar cells are restricted to a single cartridge, whereas in the proximal stratum C their collateral processes extend laterally through more than one cartridge. The collaterals of the L4-type of monopolar cells are exclusively confined to stratum C. There they are arranged bilaterally along the dorsoventral axis of the eye. Within stratum A, where all neurons are organised in well defined columns (cartridges), the axons of the short visual cells seem to be distributed over any cross section of a cartridge at random. In this layer, tangential fibres are the only candidates for inter-cartridge cross talk. In stratum C, the columnar organisation of the neuropile becomes less obvious because of the wide spread ramifications of the second order neurons. For instance, the collaterals of the L1a-type of monopolar cell extend over up to 18 neighbouring cartridges. 4) Three types ofcentrifugal fibres running from the medulla to the lamina are observed (T-fibres). Some of them form wide field arborisations either in stratum A (type T2) or in stratum C (type T3). In linear scale, their collaterals may extend over more than 40% of the large (dorsoventral) axis of the lamina. 5) Receptor terminals, especially Rs-fibres, are densely packed with elongated synaptic vesicles, whereas in second order neurons round vesicles are arranged around the presynaptic elements. Especially in Rs-fibres analyses of serial sections reveal T-shaped synaptic ribbons, which are the presynaptic sites as regards four postsynaptic elements. In case of rod-like presynaptic elements diadic and triadic arrangements of postsynaptic fibres can also be observed. Four main types of synaptic configurations are discriminated: (1) Receptor terminals synapse on second order neurons. (2) Second order neurons synapse on receptor cell axons as well as on other second order profiles. These synapses are sometimes observed in feedback configurations. (3) Synapses occuring between receptor axon terminals. (4) A small, probably efferent neurosecretory nerve fibre synapses on second order neurons. Neurosecretory fibres of larger diameters (to 1.5 Μm are frequently found in stratum C.