Social factors affecting queen fecundity in the ant Myrmica rubra

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Abstract
At the end of winter, normal populations of the polygyne ant Myrmica rubra L. consist of queens, workers and larvae; the latter are dormant and all in the third stadium. During experimental culture in artificial nests in the laboratory, the starting number of all three of these categories was varied and in some, food supply was restricted too. In a population of workers and larvae, queens do not interfere with each other sufficiently to reduce their fecundity; they avoid congestion by dispersing under the canopy of workers. Queens suffer if food is withheld; they probably feed themselves and are thus largely independent of the number of workers. Even in favourable conditions with full food, the distribution of egg‐batch sizes is not normal but follows a hollow curve that is well described by the negative binomial series. A poor food supply accentuates the hollow shape by increasing the number of non‐laying queens and reducing the number that are able to lay large batches. Larvae also suppress fecundity but only if they have sufficient food to grow actively; as their number increases, egg production by queens decreases exponentially.