Small body size in an insect shifts development, prior to adult eclosion, towards early reproduction.

Life-history theory has suggested that individual body size can strongly affect the allocation of resources to reproduction and away from other traits such as survival. In many insects, adults eclose with a proportion of their potential lifetime egg production that is already mature (the ovigeny index). We establish for the solitary parasitoid wasp Aphaereta genevensis that the ovigeny index decreases with adult body size, despite both initial egg load and potential lifetime fecundity increasing with body size.

Competitive interactions between parasitoid larvae and the evolution of gregarious development.

We report experiments using two closely related species of alysiine braconids directed at understanding how gregarious development evolved in one subfamily of parasitoid wasps. Theoretical models predict that once siblicide between parasitoid wasps has evolved, it can only be lost under stringent conditions, making the transition from solitary to gregarious development exiguous. Phylogenetic studies indicate, however, that gregariousness has independently arisen on numerous occasions.

Immobility: the key to family harmony?

The lethal fighting of larvae in many parasitoid species is a striking example of sibling rivalry. Theory has suggested that such fighting, and subsequent solitary development, might be irreversible, but phylogenetic evidence suggests otherwise. New empirical work now shows that the loss of mobility in parasitoid larvae, with the retention of fighting behaviour, is one way to escape the trap of solitary development.

Breeding soundness, libido and performance of beef bulls mated to estrus synchronized females.

Ninety-three beef bulls and 2316 females were used to determine the relationships between breeding assessments of bulls and subsequent mating performance. Each bull was given a breeding soundness examination (BSE) and two 10-min libido/serving capacity (L/SC) tests. Breeding potential of each bull was classified as satisfactory (BSE score = 60 to 100) or questionable (BSE score = 30 to 59); libido was classified as either high (mean score = 9.

Efficiency of single-sire mating programs with beef bulls mated to estrus synchronized females.

Efficiency in reference to pregnancy rates of breeding beef bulls with estrus synchronized cows and heifers was tested. Most bulls (104 of 112) were given a breeding soundness examination and two 10-min libido/serving capacity tests. Females received either Syncro-Mate-B (SMB) or two injections of Prostaglandin F(2)alpha (PGF) to synchronize estrus.