Trichogramma parasitoids alter the metabolic physiology of Manduca eggs

Egg parasitoids face unique developmental constraints. First, they have exceptionally limited resources to support themselves and their siblings through three life stages. Second, they develop within the physiological system of another species, which they modify to their own ends. We examined how these constraints affect the metabolic physiology of egg parasitism, and whether parasitoids retool their host eggshell to account for their different metabolic demands. Higher-conductance eggshells allow more oxygen to reach the developing parasitoids, but also allow more water to leave the egg. We used Manduca sexta (Lepidoptera: Sphingidae) eggs and Trichogramma (Hymenoptera: Trichogrammatidae) parasitoids from southeastern AZ, USA. Compared with unparasitized Manduca eggs, eggs parasitized by Trichogramma had lower peak metabolic rates and approximately 50 per cent lower metabolic efficiency. However, developing Trichogramma were far more efficient than typical transfer efficiencies between tropic levels (approx. 10%). Even within a few hours of parasitization, eggs containing more Trichogramma had lower per-parasitoid metabolic rates, suggesting that parasitoid larvae have mechanisms for rapidly adjusting their metabolic rates based on number of siblings. Parasitoids also appear to control the conductance of their host eggshell: their different metabolic demands were mirrored by shifts in rates of water loss.     

Respiration calorimeter for avian eggs

When studying the energetic metabolism during avian embryogenesis, it is necessary to determine simultaneously the intensity of respiration and the level of heat production. A device designed for measuring these parameters in the same object is here described.     

Regulating the market for human eggs

This essay provides a rationale for a regulated market for human oocytes. Although the commodification of human oocytes raises important moral concerns, these concerns do not justify laws banning commerce in human eggs. Given the burgeoning ART industry and the growing oocyte market, the most prudent course of action is to develop regulations for the human oocyte market that are designed to protect and promote important social values, such as health, safety, liberty, and respect for human life. Other responses, such as banning the sale of eggs altogether or allowing donors to be compensated only for their services, would either create a black market or would lead to corruption and abuse. Society still needs to debate specific rules and policies that should govern the human egg market, but further discussion of that important task is best left to legislative bodies and other commentators.     

What hospitals should do to prepare for an influenza pandemic

This article offers recommendations on what hospitals should do to prepare for an influenza pandemic and proposes specific actions and priorities for the purpose of making the discussion of hospital pandemic preparedness issues more operationally useful.