|Daane, Kent - University Of California|
|Wang, Xin-geng - University Of California|
|Nieto, Diego - University Of California|
|Pickett, Charles - California Department Of Food And Agriculture|
|Blanchet, Arnaud - University Of California|
|Johnson, Marshall - University Of California|
Submitted to: Biocontrol
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2015
Publication Date: 1/21/2015
Citation: Daane, K.M., Wang, X., Nieto, D.J., Pickett, C.H., Hoelmer, K.A., Blanchet, A., Johnson, M.W. 2015. Classic biological control of olive fruit fly in California, USA: release and recovery of introduced parasitoids. Biocontrol. 60:317-330.
Interpretive Summary: The olive fruit fly invaded California in 1998 and has since spread to all commercial olive growing regions. Management strategies rely on frequent sprays of insecticidal baits, leading to the development of resistance. To develop sustainable management practices for this pest, a classical biological program was initiated that involved the importation and release of two parasitic wasps which are important natural enemies of the olive fly in its native range in Africa. The wasps were initially released in two coastal California locations. One of the wasps, Psyttalia lounsburyi, is now established at these sites and further efforts are underway to assist its dispersal throughout olive production areas. Successful establishment will help to reduce grower costs of managing the olive fly and increase the quality of olive harvests.
Technical Abstract: The establishment of olive fruit fly Bactrocera oleae (Rossi) in California led to a classical biological program. This study reports the release and recovery of two solitary larval endoparasitoids, Psyttalia humilis Silvestri and Psyttalia lounsburyi (Silvestri) from sub-Saharan Africa, in two coastal California locations (San Luis Obispo County and San Mateo County). Both parasitoid species were recovered post-release within the same fruit season and dispersed up to 10,000 m from a release location. Psyttalia lounsburyi was recovered up to 945 days since the last release at one site and is now established in California. Investigation of interspecific competition among the imported species showed that P. humilis performed better under laboratory conditions, and the indigenous generalist ectoparasitoid Pteromalus kapaunae Heydon indiscriminately attacked hosts previously parasitized by P. humilis. The latter could negatively affect introduced endoparasitoids. We discuss major ecological factors that could impede the permanent establishment of olive fruit fly parasitoids in California.