The shape of the trade-off function between egg production and life span in the parasitoid Asobara tabida

Despite a large number of studies on the cost of reproduction, the shape of the trade-off between reproduction and survival is still unresolved. In this paper, two prominent alternatives with respect to this problem are compared in the parasitoid Asobara tabida (Nees): a linear relationship between egg production and physiological life span, and a linear relationship between egg production and intrinsic mortality rate. This is the first study that directly assesses the shape of the trade-off function between reproduction and survival in an insect parasitoid. We manipulated egg production to be low, medium or high and measured the associated life span under laboratory conditions. The results showed a decrease in mean life span with increasing egg production. The data differed significantly from a trade-off function between egg production and mortality rate, while a linear trade-off function between egg production and physiological life span produced an accurate description of the data

The shape of the trade-off function between egg production and life span in the parasitoid Asobara tabida

Despite a large number of studies on the cost of reproduction, the shape of the trade-off between reproduction and survival is still unresolved. In this paper, two prominent alternatives with respect to this problem are compared in the parasitoid Asobara tabida (Nees): a linear relationship between egg production and physiological life span, and a linear relationship between egg production and intrinsic mortality rate. This is the first study that directly assesses the shape of the trade-off function between reproduction and survival in an insect parasitoid. We manipulated egg production to be low, medium or high and measured the associated life span under laboratory conditions. The results showed a decrease in mean life span with increasing egg production. The data differed significantly from a trade-off function between egg production and mortality rate, while a linear trade-off function between egg production and physiological life span produced an accurate description of the data

A field study of size-fitness relationships in the parasitoid Asobara tabida

1. Many evolutionary models of parasitoid behaviour assume a positive correlation between size and fitness. In this paper we study the size-fitness relationship in the laboratory and in the field using females of the solitary parasitoid Asobara tabida (Hymenoptera: Braconidae). 2. In the laboratory, fecundity, fat reserves and longevity without food were positively correlated with size. 3. Release-recapture experiments in the field showed that dispersal diminishes fat reserves. Dispersal ability is size-dependent: larger females, with larger fat reserves, disperse over larger distances than smaller females. 4. The form of the relationship between size and fitness in the field was estimated in two ways: one based on a comparison of the size distribution of released and recaptured females; the other based on the egg load and fat reserves of wild-caught females. Both showed an accelerating increase of fitness with size. 5. The majority of females appeared to be time-limited. Therefore, the increase in fitness with size is predominantly due to a larger dispersal ability and not to a higher egg load

Environmental Spill-Overs Into General Community Law

This Article will illustrate that indeed, European environmental law is not just another sectoral policy area of the European Union (“EU”). Over the years it has proven to have a major impact on various general doctrines of European law. In that sense, European environmental law had (and still has) an important spill-over impact upon general European Community (“EC”) law. It is the modest ambit of this Article to illustrate some of the environmental spill-overs into general European law, specifically examining the role of the European Court of Justice (“ECJ”) and its case law