Predatory habits of dipteran larvae inhabiting Nepenthes pitchers

The food habits of some dipteran immatures inhabiting the fluid in Nepenthes pitchers were observed in Indonesia and Singapore. Predation by Aedes (Alanstonea) treubi (Culicidae), Nepenthosyrphus (Syrphidae), Nepenthomycia and Wilhelmina (Calliphoridae) and Pierretia (Sarcophagidae) is confirmed for the first time. The predatory behaviour of Lestodiplosis (Cecidomyiidae), Xenoplatyura (Mycetophilildae), Nepenthosyrphus, Pierretia and Phaonia (Muscidae) is described. Prey selection experiments carried out reveal that Tripteroides tenax (Culicidae) and Dasyhelea (Ceratopogonidae) are most susceptible to attack by Toxorhynchites (Culicidae), Nepenthosyrphus and Nepenthomyia, whereas Tripteroides nepenthis is most resistant, with Culex and Uranotaenia mosquitoes of intermediate susceptibility. Corethrella calathicola (Chaoboridae) attacks Dasyhelea, Tr. tenax and if prey is unavailable, also becomes cannibalistic. Predation is very severe in at least some Nepenthes pitchers, suggesting the importance of adaptive prey character traits for escape from predation in this habitat.