Summary 1.Ecologists concerned with life-history strategies of parasitoid wasps have recently focused on interspecific variation in the fraction of the maximum potential lifetime egg complement that is mature when the female emerges into the environment. Species that have all of this complement mature upon emergence are termed 'pro-ovigenic', while those that do not are termed 'synovigenic'. We document and quantify the diversity of egg maturation patterns among 638 species of parasitoid wasps from 28 families. 2. We test a series of hypotheses concerning variation in 'ovigeny' and likely life-history correlates by devising a quantitative index -the proportion of the maximum potential lifetime complement that is mature upon female emergence. 3. Synovigeny, which we define as emerging with at least some immature eggs, was found to be by far the predominant egg maturation pattern (98·12% of species). Even allowing for some taxonomic bias in our sample of species, pro-ovigeny is rare among parasitoid wasps. 4. There is strong evidence for a predicted continuum in ovigeny index among parasitoid wasps, from pro-ovigenic (ovigeny index = 1) to extremely synovigenic species (ovigeny index = 0). 5. As predicted, synovigenic species are longer-lived than pro-ovigenic ones, and ovigeny index and life span are negatively correlated across parasitoid taxa, suggesting a life span cost of concentrating reproductive effort early in adult life. 6. There is equivocal evidence that host feeding (i.e. consumption of host haemolymph and /or tissues by adult wasps) is confined to synovigenic parasitoid wasps. It is also not certain from our analyses whether host feeding is associated with a relatively low ovigeny index. 7. As predicted, egg resorption capability is concentrated among producers of yolkrich eggs. Also, the hypothesis that it is associated with a tendency towards a low ovigeny index is supported. Parasitoid species that produce yolk-rich eggs also exhibit a lower ovigeny index than species that produce yolk-deficient eggs. 8. Ovigeny index appears to be linked to parasitoid development mode (koinobiosisidiobiosis). 9. We conclude that 'ovigeny' is a concept applicable to insects generally.

Life-history theory proposes that costs must be associated with reproduction. Many direct costs are incurred during breeding. There is also evidence for indirect costs, incurred after breeding, which decrease survival and future reproductive success. One possible indirect cost identi¢ed in birds is that breeding activity in some way compromises plumage quality in the subsequent moult. Here we propose a mechanism by which this could occur. Breeding activity delays the start of moult. Birds that start to moult later also moult more rapidlyöan e¡ect of decreasing daylength. Could this result in poorer quality plumage? We kept two groups of male European starlings, Sturnus vulgaris, one on constant long days and the other on decreasing daylengths from the start of moult. Decreasing daylengths reduced the duration of moult from 103 § 4 days to 73 § 3 days (p 5 0.0001). Newly grown primary feathers of birds that moulted fast were slightly shorter, weighed less (p 5 0.05) and were more asymmetrical. They had a thinner rachis (p 5 0.005), were less hard (p 5 0.01) and less rigid (p 5 0.05). They were also less resistant to wear so that di¡erences in mass and asymmetry increased with time. There was no di¡erence in Young's modulus. Poorer quality plumage will lead to decreased survival due to decreased £ight performance and increased thermoregulatory costs. Thus, reproduction incurs costs through a mechanism that operates after the end of breeding.

Abstract.  1. Insects vary considerably between and within orders, and even within the same genus, in the degree to which the female's lifetime potential egg complement is mature when she emerges as an adult.2. The ‘ovigeny index’ (OI) – the number of eggs females have ready to lay divided by the lifetime potential fecundity – quantifies variation in the degree of early life concentration of egg production, and also variation in initial reproductive effort.3. Here, an integrated set of hypotheses is presented, based on a conceptual model of resource allocation and acquisition, concerning trade‐offs at the interspecific level between initial investment in egg production (as measured by OI) and other life‐history traits in holometabolous insects.4. The evidence supporting each of these hypotheses is reviewed, and particular attention is paid to the Lepidoptera, as relevant life‐history data are rapidly accumulating for this ecologically and economically important group.5. There is evidence at the interspecific level supporting: (i) a link between OI and a trade‐off between soma and non‐soma in Trichoptera and Hymenoptera (the proportionate allocation to soma decreases with increasing OI); (ii) a negative correlation between OI and dependency on external nutrient inputs (via adult feeding) in Hymenoptera and in Lepidoptera; (iii) a negative correlation between OI and the degree of polyandry (and nuptial gift, i.e. spermatophore, use) in Lepidoptera; (iv) negative correlations between OI and resource re‐allocation capabilities (egg and thoracic musculature resorption) in Hymenoptera and in Lepidoptera; (v) a negative correlation between lifespan and OI in Trichoptera, Hymenoptera, and Lepidoptera, indicating a cost of reproduction; (vi) a link between winglessness and an OI of one in Lepidoptera; (vii) a negative correlation between OI and the degree of female mobility in winged Lepidoptera; and (viii) a negative correlation between OI and larval diet breadth (as mediated by oviposition strategy) in Lepidoptera.

Summary1. The ovigeny index, previously identified as both a significant fitness variable in parasitoid wasps and an important factor in parasitoid-host population dynamics, is the proportion of the maximum potential lifetime complement of eggs that is mature when the female emerges into the environment following pupal development. We tested the hypothesis that ovigeny index varies with female body size in parasitoid wasps. Body size measurements were obtained for 40 species in 13 families, representing a broad taxonomic and morphological diversity of parasitoid wasps. There was an almost 18-fold difference in size between the smallest and the largest species. 2. Ovigeny index is shown to be negatively correlated with body size across speciessmaller wasps have a higher proportion of eggs mature at emergence than do larger wasps -a result supporting the hypothesis. This relationship has previously been observed within species. 3. The previously reported cross-species negative correlation between life-span and ovigeny index is robust, as it still holds when variation in body size is controlled for. 4. We discuss the likely selective factors in the evolution of a link between ovigeny index and body size across species.

Jervis , M. A. and Ferns, P. N. 2005. The timing of egg maturation in insects: ovigeny index and initial egg load as measures of fitness and of resource allocation. Á/ Oikos 107: 449 Á/460.Both the ovigeny index (OI) Á/ defined as the proportion of the potential lifetime complement of eggs that is mature upon female emergence, and egg load Á/ defined as the number of mature eggs carried by a female at a given moment in her lifetime, have been identified as significant fitness variables in insects. In discussions of egg maturation strategies initial egg load (IEL) and OI are often considered together, and they have been assumed to be strongly correlated. The purpose of this review is: (i) to summarise what is known about variation in OI and IEL both in relation to one another and in relation to other fitness variables (notably life-span and body size), (ii) to assess the merits of OI and IEL as measures of resource allocation to reproduction, and (iii) to contrast knowledge of the mechanisms underlying cross-species variation in these two variables with what is known concerning the mechanisms underlying intraspecific variation. Our review concentrates upon parasitoid wasps because most information on OI and IEL has been obtained for these animals, but most of the issues we address are pertinent to other insects, at least holometabolous ones. We conclude that, despite certain limitations, OI is, for insect evolutionary ecology, more useful than IEL for two reasons: (i) OI is a true measure of the degree to which lifetime egg production is concentrated into the early phase of adult life, (ii) the observed intraspecific and interspecific declines in OI with increasing body size are consistent with theoretical predictions concerning body size-related changes in reproductive effort (when the proportional change in the allocation to reproduction is considered), whereas the intraspecific alteration in IEL is not (iii) OI is a measure of the relative extent of resource allocation between the juvenile and the adult stages of the female. Lastly, we discuss the possible application of OI to insect population dynamics and management.