Clutch size as an optimal foraging problem for insects

Abstract

Many insects oviposit on food patches (e. g., hosts) that represent a finite resource. Competition for food may occur among the developing progeny with the effect of reducing their survivorship, size, and/or some other aspect of fitness. Here a simple, but general, equation is given that captures tures some of the possible relationships between the number of progeny on a host and their fitness. This in turn specifies the clutch size that maximizes the fitness of a female ovipositing on a single host (the “Lack” clutch size). The equation is then used in an optimal foraging type model to specify optimal clutch sizes when a female searches for and oviposits on a series of hosts. The model makes three general predictions: (1) for a constant host size (or value), optimal clutch size varies directly with the inter-host search time, (2) for a constant search time, optimal clutch size varies directly with host value, and, (3) females should never lay more than the Lack clutch size. The model is then extended to include optimal clutch size in superparasitism.