Roger Cammaerts

Chemical and ethological studies of the trail pheromone of the ant Manica rubida (Hymenoptera: Formicidae)

ABSTRACT. The poison gland of Manica rubida contains nanogram quantities of four alkylpyrazines, methylpyrazine, 2,5‐dimethylpyrazine, trimethylpyrazine and 3‐ethyl‐2,5‐dimethylpyrazine, of which only the last induces pronounced trail‐following behaviour. Myrmica rubra and M. rubida workers follow each others trails equally well when allowance is made for the much greater size of M. rubida workers. The cross activity in trail‐following between M. rubida, M. rubra and Tetramorium caespitum is understandable in terms of the amounts and proportions of the different pyrazines present in their glands and their responses to the synthetic substances and appropriate mixtures of them.

Foraging Area Marking in Two Related Tetramorium Ant Species (Hymenoptera: Formicidae)

The related ants Tetramorium caespitum and T. impurum mark their foraging area in a species-specific, home range and short-lasting manner. Indeed, ants reaching a new area have a slow linear speed which increases during the marking. Conspecific ants are arrested and attracted by marked areas, while heterospecific ants are reluctant to visit them. However, when the latter do visit marked areas, they move more quickly and less sinuously than conspecific ants and do not stay on the areas. The marking is performed in about 3 min by T. caespitum and in 3 to 6 min by T. impurum. If not reinforced, the marking vanishes in the same time intervals. Neither poison gland nor last sternite extracts reproduce the activity of naturally marked areas, whereas a Dufour gland extract does exactly that. Foraging ants touch the ground with the tip of their gaster. Consequently, we can postulate that the workers mark their foraging area with the contents of this gland, which is associated with the sting apparatus, and that they deposit with the extremity of the gaster. Alien conspecific ants are seldom aggressive to one another, even on marked areas. When encountering each other on unmarked areas, heterospecific ants present some aggressive reactions. On marked areas, their aggressiveness is enhanced and intruder ants are restless, while resident ones walk freely. On ground marked by T. impurum, ants of this species are more aggressive than antagonistic T. caespitum workers. The marking of foraging areas thus induces defense against heterospecifics but not against conspecific ants.

Changes in Paramecium caudatum (protozoa) near a switched-on GSM telephone.

The protozoan Paramecium caudatum was examined under normal conditions versus aside a switched-on GSM telephone (900 MHz; 2 Watts). Exposed individuals moved more slowly and more sinuously than usual. Their physiology was affected: they became broader, their cytopharynx appeared broader, their pulse vesicles had difficult in expelling their content outside the cell, their cilia less efficiently moved, and trichocysts became more visible. All these effects might result from some bad functioning or damage of the cellular membrane. The first target of communication electromagnetic waves might thus be the cellular membrane.

Thin‐layer chromatographic isolation of the trall pheromone of the ant Pheidole pallidula

Abstract. Although the presence of small amounts of 3‐ethyl‐2,5‐dimethylpyrazine (EDMP) has been reported in the poison gland of the Pheidole pallidula minor workers, this substance is not the true trail pheromone of this ant. This pyrazine acts as an attractant and a locostimulant. Appropriate solvent extractions and thin‐layer chromatography of poison glands, together with trail bioassays, have shown that another substance acts as the trail pheromone. Furthermore, there seems to be an auxiliary pheromone, acting as a synergist; this might be EDMP.

A 0.123% Stevia/Aspartame 91/9 Aqueous Solution Balances the Effects of the Two Substances, and may thus be a Safer and Tastier Sweetener to be Used

Sweeteners are presently largely consumed all over the world, essentially aspartame (North America, Europe) and stevia (South America, Asia). Aspartame has a pleasant taste but present some adverse effects; stevia has very few adverse effects but has not the sweetest taste. Using ants as biological models, we here examined if a 0.123% solution of stevia/aspartame 91/9 might have both a pleasant taste and nearly no adverse effects. We found that it did not change the ants’ food consumption while aspartame increased it and stevia slightly decreased it. It did not affect their locomotion, precision of reaction and response to pheromones as aspartame did. It did not increase their audacity as aspartame largely and stevia somewhat did. It did not affect the ants’ brood caring behavior and cognition as aspartame did, and it did not impact the conditioning ability and memory as aspartame drastically and stevia slightly did. Confronted to sugar water and a stevia/aspartame 91/9 solution, the ants equally drunk the two solutions, while having the choice between aspartame and sugar, they soon nearly exclusively chose the sugar, and while in presence of stevia and sugar, the ants progressively chose the sugar. Very probably aspartame enhanced the taste of stevia, and as the latter contains a true glycoside, a stevia/aspartame 91/9 solution did not affect the ants’ physiology and ethology as pure aspartame did. In front of sugar and a stevia/aspartame ca 96/4 solution, the ants chose the sugar. Thus, a 0.123% solution in which 9% aspartame (and no less) is mixed to 91% stevia (and no more) appears to constitute a safe and tasty sweetener which could be used instead of solutions containing only aspartame or stevia.

Can Ants Apply What They Acquired Through Operant Conditioning

Can an act learned through conditioning be adequately presented in a subsequent different situation under which it may be useful to the individuals? We approached this question, working on ants, and staying at a level basic compared to the largely developed Applied Behavior Analysis (ABA) discipline. We simply conditioned the ants of both colonies A and B to a green hollow cube (= the conditioned stimulus CS1) associated with sugar water (= the unconditioned stimulus US1), and to basilica (= the conditioned stimulus CS2) associated with meat (= the unconditioned stimulus US2). We then deprived colony A of sugar water and colony B of meat. Thereafter, when confronted to the two conditioned stimuli at the same time, the ants of colony A chose CS 1 (previously associated with sugar water), and the ants of colony B chose the CS 2 (previously associated with meat). The ants chose thus the CS corresponding to the US of which they were deprived. They applied thus a behavior learned through conditioning in a subsequent situation under which this behavior may be useful. During our test experiment, the ants strongly responded to the adequate CS due to their high motivation resulting from starvation. Conditioning techniques might also be usefully used during humans’ treatment under the ABA discipline. Increasing the patients’ motivation during some conditioning performed for caring them may enhance the impact of that conditioning on the treatment efficiency.

Spatial expectation of food location in an ant on basis of previous food locations (Hymenoptera, Formicidae)

We examined if workers of the ant species Myrmica ruginodis would be able to localize a food source on the basis of its previous locations. To this end we progressively relocated food to predefined positions, both linearly, i.e., farther or nearer the nest entrance, and circularly, i.e., to the left or to the right of the nest entrance. After removal of food from one site and prior to the subsequent relocalization of the food to the next site, we counted the number of ants present at the different possible food locations. We found that the ants initially came to the site from where the food had just been removed, but following two or three relocations of food, they foraged around the following, expected food location in statistically significant numbers. The workers thus appeared to be able to spatially anticipate where food would be on the basis of its previous localizations. Such ability—hitherto unreported in ants—requires a knowledge of the environment around the nest, a long-term visual memory, memorization of the location of some food locations, knowledge of the pattern of food supply, some degree of providence, presentation of some anticipative behavior, and estimation of their orientation of movement and distances walked. These seven capabilities have been separately observed in previous studies on Myrmica species. Here, we report that the ant M. ruginodis also has the ability to learn a relation between previous food sites and a next one.