The morphology and biology of the entomophilic Thripinema fuscum (Tylenchida: Allantonematidae), and the histopathological effects of parasitism on the host Frankliniella fusca (Thysanoptera: Thripidae)

We used light and electron microscopy to detail the in vivo life cycle of the nematode Thripinema fuscum and to determine the effects of parasitism on tissues of the thrips host Frankliniella fusca. The parasitic T. fuscum female produced eggs within 4–5 days after ingress and the host haemocoele became packed with eggs and developing juvenile nematodes. Mature juveniles migrated to the hindgut and fully developed juveniles first emerged from the posterior end of the male or female F. fusca 9 days after parasitization. Parasitization induced a displacement of the host alimentary tract, an atrophy of the ovaries and fat body, and an alteration of energy and waste reserves in host tissues. Our observations reveal a specialized relationship showing that this parasite is well adapted to exploit the host digestive, reproductive and excretory systems.