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1. Dynamic models of optimal foraging predict that an animal's decision to accept or reject a patch depends not only on the environment and patch quality, but also on its internal state. Previous experiments have shown that the two-spot ladybird beetle,Adalia bipunctata(L.), is reluctant to lay eggs in a patch of prey contaminated by the oviposition-deterring pheromone produced by conspecific larvae.2. An experiment was conducted to test whether the internal state of anA. bipunctatafemale affects its oviposition response to oviposition-deterring pheromone. Firstly, the oviposition response to oviposition-deterring pheromone of young and old females was compared. Secondly, the oviposition response to oviposition-deterring pheromone of females previously exposed continuously to oviposition-deterring pheromone was compared with that of females of the same age but with no previous experience of oviposition-deterring pheromone.3. Old females and females with previous experience of oviposition-deterring pheromone were less reluctant to lay eggs in the presence of oviposition-deterring pheromone than young and naive females. These results are consistent with the predictions of optimal foraging theory. [ABSTRACT FROM AUTHOR]

1. The literature on ladybirds indicates that males are consistently smaller than females but take the same length of time to complete their development. Rearing Adalia bipunctata at 20 and 25 °C confirmed that protandry cannot account for sexual size dimorphism in this species, nor can a difference in egg size. 2. Female larvae consumed more food and had a higher relative growth rate in the fourth instar than did male larvae. 3. When food is limited, small males appear to be more successful at mating than are large males. 4. To account for these results, it is hypothesised that the gonads of male larvae compete more strongly with the soma for resources and that this reduces the growth potential of the soma of male larvae relative to that of female larvae. The greater mating success of small males when food is limited supports the eat or mate hypothesis, which predicts that when food is limited small males will spend less time feeding and more time mating than will large males. [ABSTRACT FROM AUTHOR]