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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.

Parasitoids display remarkable inter- and intraspecific variation in their reproductive and associated traits. Adaptive explanations have been proposed for many of the between-trait relationships. We present an overview of the current knowledge of parasitoid reproductive biology, focusing on egg production strategies in females, by placing parasitoid reproduction within physiological and ecological contexts. Thus, we relate parasitoid reproduction both to inter- and intraspecific patterns of nutrient allocation, utilization, and acquisition, and to key aspects of host ecology, specifically abundance and dispersion pattern. We review the evidence that resource trade-offs underlie several key intertrait correlations and that reproductive and feeding strategies are closely integrated at both the physiological and the behavioral levels. The idea that parasitoids can be divided into capital-breeders or income-breeders is no longer tenable; such terminology is best restricted to the females' utilization of particular nutrients.

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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.