Are behavioural changes in parasitised aphids a protection against hyperparasitism

Parasitised aphids often leave the aphid colony before mummification. It has been suggested that this behaviour is an example of host manipulation by the primary aphidiid parasitoid to reduce the risk of hyperparasitism after mummy formation. Mummification site and hyperparasitism risk are surveyed in 16 species of aphid. Mummification away from the colony was not associated with reduced hyperparasitism. In ant-attended species, and in species with well developed parasitoid defence behaviour (such as kicking), mummies formed within the colony tended to suffer less hyperparasitism. In laboratory experiments, two hymenopteran ectohyperparasitoids, Dendrocerus carpenteri (Curtis) (Megaspilidae) and Asaphes vulgaris (Walker) (Pteromalidae), were more successful attacking parasitised aphids [Uroleucon jaceae (L.) (Aphididae)] when the mummies were outside the colony, not surrounded by living aphids.