Life History Variation in Planthoppers

Abstract

Life history theory seeks to explain variation in reproductive traits such as fecundity, age to first reproduction, and egg size as well as traits which synchronize reproduction with favorable resources in space (migration) and time (diapause and voltinism) (Stearns 1976, 1977, 1980; Denno and Dingle 1981). Individuals are bound by natural selection to maximize the number of progeny they leave in subsequent generations (Stearns 1976). However, the combinations of characteristics (life history strategies) that result in maximum offspring survival are tremendously diverse among the insects and for planthoppers as well (Denno and Dingle 1981; Denno et al. 1991). For example, in planthoppers, Toya propinqua deposits many (lifetime fecundity > 1000) small eggs (0.66 mm in length) (Raatikainen and Vasarainen 1990), whereas Perk insiella saccharicida deposits fewer (300), but larger (1.2 mm) eggs (Williams 1957; Fennah 1969). The particular combination of traits that evolves will depend not only on selection but also on the phenotypic trade-offs and costs between traits, the genetic variance and covariance among traits, and phylogenetic constraints (Denno and Dingle 1981; Denno and Roderick 1990).