RESPIRATION IN DROSOPHILA .3. INFLUENCE OF PREIMAGINAL ENVIRONMENT ON RESPIRATION AND AGEING IN DROSOPHILA MELANOGASTER HYBRIDS

Rate of oxygen consumption, daily, mean and total fecundity, fertility and adult life span of Drosophila melanogaster imagos were measured, at 25°C, from emergence up to death. Reciprocal hybrids, from the cross between two highly inbred lines, Gabarros 4 and Abeele, produced at preimaginal densities of 30 and 240 eggs per standard tube of 5·7 cm2 of surface, were used. The respiration measurements were carried out according to the technique of Gregg and Lints; all the measurements were realized on individual females; age, size and weight were taken into account. Increase of the preimaginal eggs (and larvae) density reduces the size of the emerging adults, prolongs the duration of development and lengthens the adult life span; the total fecundity do not appear to vary considerably; the mean fecundity, however, is much smaller, the egg-laying period is prolonged and the maximal daily egg production is attained later. Between emergence and death the two reciprocal hybrids have almost identical mean respiration rates at both the population (eggs and larvae) densities studied. Respiration rate decreases with age in both hybrids when larval population density is 30 eggs per tube. There is no relation between respiration rate and age for either hybrid at population density of 240 eggs per tube. No relation emerges between rate of oxygen consumption and the other quantitative traits measured when all four genotype-environment combinations are considered together. Specifically the observations do not reveal any correlation between mean rate of oxygen consumption and mean daily egg-production, or between mean rate of oxygen consumption and life span. The results are discussed in relation with different ageing and respiratory control theories. © 1969.