Maternal rearing condition and age affect progeny fitness in the parasitoid waspLysiphlebus fabarum

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AbstractMaternal rearing conditions are expected to affect fitness components of progeny so that maternal effects effectively protect offspring from environmental stressors. The objective of this study was to elucidate the interaction between maternal rearing condition, age, and offspring rearing condition in the parasitoid waspLysiphlebus fabarum(Marshall) (Hymenoptera:Braconidae,Aphidiinae). The effects of maternal age, body size, and host instar used for development on fitness components of progeny were evaluated. Host was the black bean aphid,Aphis fabaeScopoli (Hemiptera: Aphididae). Results indicated that small and young mothers (developing in first‐instar hosts) produced progeny with a longer developmental time compared to large and old mothers (developing in second‐instar hosts). Progeny that hatched from larger eggs also had a larger body size. There were, however, no significant differences in the size of progeny that developed in different host instars. Progeny that hatched from large eggs had a higher initial egg load, and progeny produced by younger mothers had larger eggs. These differences were significant only when progeny developed in the first host instar, whereas in the second and fourth instar no differences were observed. Our findings indicate that progeny with larger size at the egg stage had superior fitness. Age‐specific maternal effects were not as strong as the effect of the mother's body size. Although the interaction between host instar of progeny development and maternal rearing condition was not statistically significant, developing in suboptimal instars led to trade‐offs between fitness components in progeny. The ecological significance of these findings is discussed.