Parasitoid fauna of Queensland fruit fly, Bactrocera tryoni Froggatt (Diptera: Tephritidae) in inland New South Wales, Australia and their potential for use in augmentative biological control

Abstract

Augmentative releases of parasitic wasps may improve management of the Queensland fruit fly, Bactrocera tryoni Froggatt, in inland New South Wales (NSW). A survey was conducted from October 2008 to April 2009 to detect the presence of parasitoids of fruit fly. Fruit fly-infested fruits were collected in Wagga Wagga, Cootamundra, Ganmain, Gundagai, Lockhart and Lake Cargelligo on the south-west slopes and plains of NSW and Albury-Wodonga on the NSW-Victorian border. Two species of opiine parasitoids were detected: Diachasmimorpha kraussii (Fullaway) and D. tryoni (Cameron); both species from fruits that also yielded B. tryoni and island fruit fly, Dirioxa pornia (Walker). Nine per cent of fruit samples yielded parasitoids. There were statistically significant differences between fruit type, fruit species, sampling events and towns. Fruit fly parasitoids were most commonly detected in fig (27.2% of samples), followed by stone fruit (11.5%), pome fruit (6.1%), loquat (4.3%) and citrus (2.1%). Parasitoid incidence varied throughout the fruit fly season, peaking in February–March 2009 (17.4%). Of the towns surveyed, Cootamundra had the highest incidence of parasitoids (28.8%), followed by Wagga Wagga (9.5%), Gundagai (10.2%) and Lockhart (1.2%), with no parasitoids detected in Albury-Wodonga, Ganmain or Lake Cargelligo. Diachasmimorpha tryoni was detected in all surveys except January–February 2009, during a heatwave. Diachasmimorpha tryoni was most prevalent in November–December 2008 (5.2%). Diachasmimorpha kraussii was most prevalent in February–March 2009 (14.5%), but was not detected in October 2008 or April 2009. Diachasmimorpha tryoni was detected in Wagga Wagga (6.1%) and Cootamundra (1.9%), with D. kraussii detected in Wagga Wagga (9.5%), Cootamundra (26.9%), Gundagai (10.2%) and Lockhart (1.2%). The presence of these parasitoid species in the region suggests they may be suitable for augmentative release in the control of B. tryoni in inland NSW.