Competitive Superiority of Early Acting Species: A Case Study of Opiine Fruit Fly Parasitoids

Abstract

Koinobiont parasitoids that attack an early host stage may have an advantage in suppressing competing parasitoids that attack later stages of the same host. We examined the competitive interaction between the two most important parasitoids of tephritid fruit flies in Hawaii, Fopius arisanus (Sonan), and Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae). The former species attacks host eggs while the latter attacks host larvae, and both species emerge as adults from the host puparia. F. arisanus physiologically suppressed egg development of D. longicaudata. Over 90% of D. longicaudata eggs died in the presence of F. arisanus larvae within host larvae of either the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) or the oriental fruit fly, Bactrocera dorsalis (Hendel). D. longicaudata appeared not to discriminate against hosts previously parasitized by F. arisanus. The mechanism that F. arisanus uses to eliminate D. longicaudata is similar to that which it employs to eliminate five other larval fruit fly parasitoids so far reported in Hawaii. This suggests that there is a broad competitive superiority of the early acting species in fruit fly parasitoids. We discuss the implication of this in relation to future biological control introductions against tephritid fruit flies.

Keywords:

• biological control
• competitive superiority
• Diachasmimorpha longicaudata
• Fopius arisanus
• interspecific competition
• koinobiont parasitoids
• tephritid fruit flies

Acknowledgments

We thank Terri Moats, Kauai Agricultural Research Center, University of Hawaii, for her assistance in this study, and the USDA-ARS Pacific Basin Agricultural Research Center, Honolulu, Hawaii, for kindly providing parasitoids and tephritid eggs. We also thank John Sivinski, Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, Gainesville, Florida; Mohsen M. Ramadan, State of Hawaii Department of Agriculture; and Aimé H. Bokonon-Ganta and Ekhlass Jarjees, University of Hawaii, for their valuable comments on an early draft of this paper. This research was supported by USDA-ARS grant No. 5853208147 to R.H.M. This is publication No. 4646 of the University of Hawaii, College of Tropical Agriculture and Human Resources Journal Series.