Polygyny in the Neotropical termite Nasutitermes corniger: life history consequences of queen mutualism

Abstract

ecological aspects of monogyny and polygyny in social insect colonies are important in comparing individual queen reproductive success. Inseminated, fecund, multiple foundresses are common in some groups of ants and eusocial wasps, but true polygyny in termites has not previously been studied. One third of Nasutitermes corniger (Isoptera: Termitidae) colonies sampled in areas of young second growth in Panama contained from 2-33 primary queens (not supplementary or neotenic reproductives). All queens in polygynous associations were fully pigmented, physogastric egg layers within a single royal cell. Multiple kings were found less frequently; true polyandry is apparently restricted to immature polygynous colonies. Data on queen weight and morphological features, and on colony composition, show that queens in polygynous nests are young and that a transition from polygyny to monogyny probably occurs after several years. The escalated growth rate of multiple queen colonies removes them from the vulnerable incipient colony size class more rapidly than colonies initiated by a single foundress, and gives them sufficient neuter support staff (workers and soldiers) to enable earlier production of fertile alates. Using a population model (Leslie matrix) I construct isoclines of equal population growth which show values of early age class probability of survival and reproductive output favoring monogyny or polygyny under individual selection. This model of queen mutualism accounts for the risk of a female in a polygynous group not succeeding as the final surviving queen. Multiple primary queens are considered rare in termites, but a review of the literature demonstrates that they may be more widespread than is currently recognized. Polygyny in termites has received scant attention but is of significance as an example of a further ecological and evolutionary convergence between the phylogenetically independent orders Isoptera and Hymenoptera. © 1984 Springer-Verlag.