Food deprivation increases reproductive effort in a parasitoid wasp

Abstract

Life history theory predicts that animals should increase their current reproductive effort as the probability of survival to the next reproductive opportunity decreases. We studied the effects of food depletion on life history and oviposition behavior in the egg parasitoid Paratelenomus saccharalis (Hymenoptera: Platygastridae) to determine if the parasitoid alters its reproductive strategy based on life expectancy. We first examined survivorship and reproductive effort of females provided only with water (i.e. starved) and females fed honey. Fed females lived up to 40 days, whereas starved females lived only up to 4 days. Fed females produced more offspring during life and had a higher net reproductive rate, i.e. R0, compared to starved females. Starved females did produce more offspring on the first day of emergence, however, and the intrinsic rate of natural increase, i.e. rm, did not differ between honey-fed and starved females. We further observed oviposition behavior in response to food availability during 24 h on the first day of emergence to determine the mechanism by which starved females increased reproductive output. Results showed that starved females oviposited more frequently than honey-fed females, and that the time required for a single oviposition was shorter for starved females. These results revealed that starved females had higher oviposition rates on the first day of emergence, leading to the similar rm of starved and fed females. This indicates that P. saccharalis altered their oviposition behavior to maximize their fitness under food-depleted conditions.