Study of the influence of the queen on brood-rearing in ants of the genus Myrmica

Abstract

The queen affects larval growth in Myrmica scabrinodis Nyl. and M. rubra L. in such a way as to cause an earlier start, improved survival, a smaller pupal size, and a diminished production of gynes. The first three effects apply to males as well as females. The magnitude of the size reduction does not regress on larval number if workers are constant but it does rise to a limit if workers are increased and larvae constant. Detailed studies of larval growth and the growth of wing buds in the final instar show that suppression occurs throughout ontogeny and that there are no accelerations of development other than those that normally occur in worker production. This applies to both sexes. Queens vary a good deal in their potency but agree in showing an increase during cultivation. There is no quantitative relation between effect and queen number. Workers taken from an active queen do not carry the effect. The presence of a queen reduces egg size in worker ovaries. No measurable effect is obtained from either winged or wingless gynes, and gynes cannot be used as a substitute for queens in experiments. If dead queens are given to workers at regular intervals an effect can be produced. No satisfactory method has been found of extracting an effective substance but the possibility of such a substance being a volatile product of the mandibular glands cannot be ruled out. Workers cannot distinguish larvae that have been with queens from those that have not. The presence of a queen does not seem to affect larval appetite for food.