Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2009
Publication Date: 5/27/2009
Citation: Hannah, N., Daane, K., Hoelmer, K.A., Pickett, C., Johnson, M. 2009. Non-target host risk assessment of the idiobiont parasitoid Bracon celer (Hymenoptera:Bracondiae) for biological control of olive fly in California.Biocontrol Science and Technology. 19:701-715.
Interpretive Summary: Risk assessment for possible harm to non-target species is an essential step in evaluating candidate agents for biological control. Several candidate species have been under study as possible biological control agents for the olive fruit fly, Bactrocera oleae, which recently became established in California, USA. The non-target risk posed by the African fruit-fly parasitoid, Bracon celer, was studied in the laboratory by examining its behavioral and reproductive response to several non-target fruit fly species that included one native fruit fly and two beneficial flies important for weed biological control. The results of indicates that Bracon celer has a broad physiological host range. Although ecological data suggests that risk to most non-target fruit flies from Bracon celer in California would be low, the potential risk to a beneficial fruit fly should preclude its release unless more extensive information on habitat location behavior becomes available.
Technical Abstract: The non-target risk posed by the African fruit-fly parasitoid, Bracon celer Szépligeti (Hymenoptera: Braconidae), was assessed as part of a classical biological program for the olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae: Dacinae) in California, USA. Behavioral and reproductive responses to non-target tephritid species were conducted with two beneficial (Chaetorellia succinea [Costa] and Parafreutreta regalis Munro) (Tephritidae: Tephritinae) and one native (Rhagoletis fausta [Osten Sacken]) (Tephritidae: Trypetinae) fruit fly species in successive no-choice and choice experiments (with the target species) under close confinement in the laboratory. Non-target host habitats were comprised of a flower head, a stem gall, and a fruit. Bracon celer probed all three non-target plant structures containing tephritid larvae, but significantly less than in olives infested with B. oleae. Results may have been influenced by prior parasitoid experience with the target host. The parasitoid was unable to penetrate yellow starthistle flower heads. Offspring were produced from P. regalis in stem galls. Comparisons of host survival in negative controls and groups of B. oleae and R. fausta exposed to B. celer indicate that, under confinement, the wasp killed more hosts than it parasitized. Reproduction on P. regalis indicates that B. celer has a broad physiological host range. Although limited access to non-target hosts due to temporal and physical factors indicates low risk to most non-target tephritids by B. celer in California, the potential risk to the beneficial P. regalis should preclude its release unless further information on habitat location behavior becomes available.