Myrmica rubra

The function of alkaloids in 30 species of ladybirds has been discussed. The presence of alkaloids is shown to be related to the existence of aposematic colour and not to their carnivorous or phytophagous nature. Alkaloids constitute an effective defence against predators, e.g. ants, Myrmica rubra, and quails, Coturnix coturnix. 

Myrmica rubra show that salicylaldehyde is a more potent deterrent that salicin (63) or its aglycone saligenin (83), The eggs of some of the beetles that feed on members of the Salicaceae contain salicin. Salicylaldehyde is detected in neonate larvae, suggesting that salicin is quickly converted to the aldehyde (Pasteels et al., 1986 Rowell-Rahier and Pasteels, 1986). This shift to members of the willow family appears to have occurred at least three times independently. The species that shifted are able to exploit a food source, yet are well protected. The larvae are provided with an additional method of defense the adults are able to sequester sufficient salicin in the eggs to make them potentially lethal to ants and to provide protection for the neonate larvae (Pasteels et al., 1986, 1988, 1989 Rowell-Rahier and Pasteels, 1986). 

Age effects may influence an individual s reaction to a chemical stimulus. Thus, in Myrmica rubra ants (see Section 11.5.3) callow individuals respond only to Dufour s gland secretions whereas older ants are attracted by both mandibular and Dufours gland pheromone (Cammaerts, 1974). Additionally, sensory adaptation or habituation can influence response level to a stimulus (Waage, 1979 Weseloh, 1980). 

Cammaerts, M. C. (1974) Production and perception of attractive pheromones by differently aged workers of Myrmica rubra (Hymenoptera Formicidae). Insectes Soc., 21, 235-48. 

Cammaerts, M. C., Inwood, M. R., Morgan, E. D., Parry, K. and Tyler, R. C. (1978) Comparative study of the pheromones emitted by workers of the ants Myrmica rubra and Myrmica scabrinodis. J. Insect Physiol., 24, 207-14. 

Fig. 15.9 Aggressive recruitment in Myrmica rubra, A worker (the black ant) runs around an intruder Lasius flavus, the white ant), depositing the Dufour s gland secretion, then stings, and returns towards the nest laying a poison gland trail. In the nest area she alerts nearby workers (shaded), and returns to the intruder, depositing streaks of attractive Dufour s gland material on top of the poison gland trail (after Cammaerts-Tricot, 1974b).

Cammaerts-Tricot, M.-C. (1974b) Piste et pheromone attractive chez la fourmi Myrmica rubra. J. comp. Physiol, y 88, 373-82. 

Plate 18 A worker of the garden ant Myrmica rubra following an artificial trail of synthetic 3-ethyl-2,5-dimethylpyrazine on paper. Note the position of the antennae. The sting lance is protruded, probably re-enforcing the trail with more pheromone. The paper is ruled in 0.1 inch (2.54 mm) squares (Photo Terry Bolam)... 

---