The ectoparasitic pupal parasitoid, Pachycrepoideus vindemmiae (Hymenoptera: Pteromalidae), attacks other primary tephritid fruit Xy parasitoids: host expansion and potential non-target impact

Pachycrepoideus vindemmiae Rondani is an ectoparasitic idiobiont parasitoid attacking puparia of many cyclorrhaphous Diptera. This study investigated its potential impact as a facultative hyperparasitoid of four other primary tephritid fruit Xy parasitoids in Hawaii, Fopius arisanus (Sonan), Diachasmimorpha longicaudata (Ashmead), Diachasmimorpha kraussii Fullaway, and Psyttalia concolor (Szépligeti). F. arisanus attacks host eggs while the latter three species attack host larvae, and they all emerge as adults from host puparia. P. vindemmiae successfully developed from host puparia previously parasitized by all of the other four tephritid parasitoids. There were no signiWcant diVerences in developmental time or body size of P. vindemmiae adults reared from these secondary host species. However, P. vindemmiae reared from the secondary hosts were smaller than those from the tephritid hosts Bactrocera cucurbitae (Coquillett) or Bactrocera latifrons (Hendel); and were larger than those reared from Drosophila melanogaster Meigen. Female P. vindemmiae developed faster on D. melanogaster but slower on Ceratitis capitata (Wiedemann) than on the other hosts. P. vindemmiae did not prefer to attack unparasitized hosts rather than hosts previously parasitized by F. arisanus, and there was no diVerence in oVspring survival and sex ratio between the wasps reared from the primary and secondary host species. Among the three distinctly diVerent size host species, B. latifrons, C. capitata, and D. melanogaster, P. vindemmiae preferred to attack the smallest host (D. melanogaster), but invested more female oVspring on the largest host (B. latifrons). There was no diVerence in oVspring survival between those reared on D. melanogaster and C. capitata, but the adult emergence rate was lower in B. latifrons than in the other two species. The Xexible body growth and less discriminative nature of P. vindemmiae indicate that it has the potential for host range expansion and thus non-target impact to other beneWcial parasitoids of Diptera.  2004 Elsevier Inc. All rights reserved.