Regulation of the production of female sexual morphs in the ant Myrmica rubra Linnaeus

Evesham, Elizabeth Jane Margaret (1982) Regulation of the production of female sexual morphs in the ant Myrmica rubra Linnaeus. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

It has been assumed that queens of the polygyne ant Myrmica rubra L. cluster, and yet contact is needed for them to exercise control over the society. To explore this apparently contradictory situation, experiments and observations were made using laboratory plastic rests and soil slices, held in place by glass, in which workers excavated their own chamber system. Four principal lines of approach were adopted: 1. Queen distribution and interaction with workers. 2. Attractiveness of queens to workers. 3. The distribution of food between colony members. 4. The sensitization of young workers to queens. Queens were not fully dispersed but tended to show a slight aggregation and this was shown, by observation, to be due to mutual avoidance and aggression. A dominance hierarchy was established such that the top queens were sedentary while others more mobile. The latter appeared unsettled, moving quickly throughout the nest and frequently fighting with other queens. The less active queens attracted workers which fed and groomed her and assisted with egg-laying. These workers carried brood and eggs into the sedentary queen zones. Queens varied in their ability to attract workers, which remained faithful to a particular queen, often the first one with which they were presented at the start of an experiment. Workers undoubtedly manipulated queens, trying to keep them in small groups and breaking-up larger associations by active bombardment. An optimum composition (queens/workers/larvae) was shown which maximised food distribution. When given an adequate worker number, larvae were approached with difficulty when supernumerary queens physically blocked worker access. Worker brood-rearing depended an their past experience of queens as well as whether queens were present or absent in a culture. Workers were sensitized to queen presence between the third and fourth week after emergence. Therefore, queens and workers were discovered to interact in a number of interesting ways, revealing patterns in colony behaviour never disclosed in this species or any ant before. All of which in fact aid, either directly or indirectly, in the control of colony growth and reproduction. The organisation of the society proved to oe much more complex than had previously been imagined.

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