Mechanisms of female mate choice in the black-horned tree cricket, Oecanthus nigricornis (Orthoptera: Gryllidae: Oecanthinae)

Sexual selection theory predicts that females will frequently choose mates and this may occur at any point prior to the release of offspring. Although females generally have a number of potential mechanisms for choosing mates, the vast majority of research on female choice has focused on choice expressed prior to copulation. Moreover, whereas females should be expected to weigh the value of both material and genetic benefits when choosing mates, previous studies have generally concentrated on either one or the other.;I studied multiple mechanisms and criteria of female mate choice in the black-horned tree cricket, Oecanthus nigricornis (Orthoptera: Gryllidae), a species in which females locate males by their calling song, and males feed mates with a secretion produced from a gland on the metanotum. In Chapter 1 I describe the mating behavior of O. nigricornis and test whether females accept or reject copulations on the basis of male phenotype and courtship behavior. I show that females mate with larger males and males that court most intensely. However, this large-male advantage occurs when males court females in the presence of rivals and appears to be the outcome of aggressive male-male competition and not active female preference of one male over another.;In Chapter 2 I show that song is a reliable indicator of male size and age and females choose songs indicative of larger males. I then present females with songs under different situations to study whether female mate choice requires a direct comparison of male calls.;In Chapter 3 I outline theory on postcopulatory mate choice and present a study of this "cryptic" choice in the black-horned tree cricket. My results show that females may manipulate spermatophores and vary their oviposition rates in ways that favor both larger males and males that provide longer periods of courtship feeding.;Finally, in Chapter 4 I examine remating by female tree crickets, as both a potential mechanism of mate choice and as a way of acquiring additional resources from males. I show that females remate quickly and indiscriminately when food is scarce but take on second mates more slowly and more discriminately when food is abundant.