Putting more eggs in the best basket : clutch size regulation in the comma butterfly

• 1. Many studies have identified different factors influencing clutchsize regulation, primarily within various groups of insects. One prediction is that ovipositing females should increase clutch size with host quality. However, in many studies it is not clear whether ovipositing females are responding to host quality or quantity. 2. Females of the polyphagous comma butterfly, allowed to oviposit on two hosts differing greatly in quality: the preferred host, stinging nettle (Polygonia c-album (L.), wereUrtica dioica L.), and the low-ranked host, birch (Betula pubescens  Ehrh). Ovipositing females were observed visually and clutch sizes were recorded. The experiment was repeated in three different years; in total, 938 observations of oviposition events were made. 3. In all three years, females ovipositing on (median 1.6–1.85) compared with females ovipositing on 1.0–1.3) three years were pooled. 4. Thus, on better hosts. It is suggested that the proximate mechanism is likely to be a response to the same stimuli used for female ranking of host plants in the preference hierarchy. U. dioica laid larger clutchesB. pubescens (median. The difference was significant in two out of three years and when allP. c-album females exhibit clutch-size regulation, with larger clutches

Nyckelord

Batches

host quality

life history

performance

preference

reproductive

zoologi

Zoology

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