Journal Article

Effect of <i>Tetrastichus giffardianus</i> (Hymenoptera: Eulophidae) on Nontarget Flowerhead-Feeding Tephritids (Diptera: Tephritidae)

Jian J. Duan and Russell H. Messing

in Environmental Entomology

Published on behalf of Entomological Society of America

Volume 27, issue 4, pages 1022-1028
Published in print August 1998 | ISSN: 0046-225X
Published online September 2014 | e-ISSN: 1938-2936 | DOI: http://dx.doi.org/10.1093/ee/27.4.1022
Effect of Tetrastichus giffardianus (Hymenoptera: Eulophidae) on Nontarget Flowerhead-Feeding Tephritids (Diptera: Tephritidae)

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We conducted laboratory tests and field surveys to evaluate the impact of a deliberately introduced fruit fly parasitoid, Tetrastichus giffardianus Silvestri, on 2 nontarget flowerhead-feeding tephritid flies, Trupanea dubautiae (Bryan) and Ensina sonchi (L.). The former is an endemic Hawaiian tephritid, infesting flowerheads of the composite shrub Dubautia raillardioides Hillebrand; the latter is an inadvertently introduced tephritid infesting flowerheads of the weed Sonchus oleraceus L. In the laboratory, gravid T. giffardianus were able to parasitize late instars of both T. dubautiae and E. sonchi when the fly larvae were dissected out of their respective host flowerheads (i.e., natural microhabitats) and presented in petri dishes. The parasitoid offspring developed successfully into adult males and females. However, no T. dubautiae and few (<1.5%) E. sonchi were attacked by T. giffardianus when presented in their respective host flowerheads. Two vagrant exotic parasitoids, Habrocytus elevatus (Walker) and Euderus metallicus (Ashmead), were reared from field-collected D. raillardioides flowerheads infested with T. dubautiae. H. elevatus also was reared from S. oleraceus flowerheads infested with E. sonchi. However, not a single T. giffardianus was recovered in extensive field surveys of both T. dubautiae and E. sonchi on Kauai Island. Thus, although late instars of both T. dubautiae and E. sonchi are suitable for the physiological development of T. giffardianus progeny, the parasitoid is unlikely to affect either species under natural conditions because the host microhabitats are not suitable for gravid parasitoids to find and oviposit in the resident fly larvae.

Keywords: Tephritidae; Tetrastichus giffardianus; biological control; nontarget effects; insect conservation

Journal Article.  0 words. 

Subjects: Entomology

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