Development of teratocytes associated with Microctonus aethiopoides Loan (Hymenoptera : Braconidae) in natural and novel host species

A laboratory study investigated development of teratocytes derived from the parasitoid Microctonus aethiopoides Loan in the natural host, Sitona disco ideus Gyllenhal, and in three novel hosts. the introduced weed biological c ontrol agent Rhinocyllus conicus (Froehlich), and two New Zealand native sp ecies Nicaeana cervina Broun and Irenimus stolidus Broun. Weevils were expo sed to parasitoids and then examined 6, 10 and 15 days post-parasitism for parasitoid stage and size, and teratocyte number and size. In all hosts. te ratocyte numbers decreased and size increased as parasitoid development pro gressed, although 6 days after parasitism, fewer, larger teratocytes were f ound in I. stolidus than S. discoideus or N. cervina. In weevils containing second-third instar parasitoid larvae, the most permissive hosts, S. disco ideus and N. cervina contained more teratocytes than the least permissive h osts I. stolidus and R. conicus. Host gender influenced some aspects of par asitoid and teratocyte development. Total teratocyte volume was greater in female than male S. discoideus at all sampling times, and at 10 days post-p arasitism in N. cervina. A possible relationship between host suitability a nd teratocyte development is discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.