Superparasitism is a widespread phenomenon. Having accepted superparasitism, mated female parasitoids must decide on the sex of each egg they subsequently lay into the same host. Theory predicts that this decision is either based on host quality, when more male eggs are laid in hosts that are already parasitized because they are perceived to be of poorer quality; or more eggs are laid of the sex that is most likely to be a strong larval competitor, i.e. generally females.

Anastatus disparis is a facultative endoparasitic egg parasitoid. We used ‘artificial’ hosts to explore outcomes of decision making by A. disparis during superparasitism under a manipulated absence of larval competition. When only one egg was laid it was always female. As the number of eggs laid increased, so more of them were male. This supports the theory that oviposition decisions are based on host quality; more male eggs were laid in hosts that were already parasitized and thus of poorer quality.

In a second experiment, eggs were exposed to parasitoids for different periods of time. Half the eggs were dissected to determine the number of parasitoid eggs that had been laid. The remaining eggs were incubated and the number and sex of offspring that ultimately emerged, following larval competition, were recorded. Under superparasitism conditions fierce larval competition ensued; only one offspring survived and they were predominantly female.

In conclusion, oviposition decisions by female A. disparis accepting self-superparasitism were made based on host quality.

超寄生是一种普遍现象。交配的雌性寄生虫接受了超寄生虫后，必须决定其随后产入同一宿主的每个卵的性别。理论预测这种决定要么基于寄主质量，要么是因为被认为质量较差而已经被寄生的寄主中产下了更多的雄卵。一个或多个卵产下最有可能成为幼虫强有力竞争者的性别，即通常为雌性。

Anastatus disparis是兼性的内寄生卵类寄生虫。我们使用“人工”宿主探索了在无寄生幼虫竞争的情况下，超寄生虫期间A. disparis做出的决策结果。当只产一个卵时，它总是雌性。随着产卵数量的增加，更多的是雄性。这支持了产卵决策基于宿主质量的理论。在已经被寄生的宿主中产下了更多的雄性卵，因此质量较差。

在第二个实验中，将卵暴露在不同时间的寄生虫中。解剖一半卵，以确定已经产下的寄生虫卵的数量。孵化剩余的卵，并记录幼虫竞争后最终出现的后代的数量和性别。在超寄生性条件下，随之而来的是激烈的幼虫竞争。只有一个后代幸存下来，而且他们主要是雌性。

总之，雌性A.disparis接受自我超寄生的产卵决定是基于宿主的质量。