Comparative evaluation of two olive fruit fly parasitoids under varying abiotic conditions

Abstract

Psyttalia lounsburyi (Silvestri) and P. humilis (Silvestri) (Hymenoptera: Braconidae) were evaluated in California for their potential to control the invasive olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae). Psyttalia lounsburyi is a specialist on B. oleae while P. humilis also attacks other tephritid species. Field cage trials, conducted from 2006 to 2009, were used to compare P. lounsburyi and two populations of P. humilis (Kenya and Namibia) in California's interior valley and coastal regions. Both parasitoid species reproduced on B. oleae in all trials. Under similar abiotic conditions, offspring production per female was higher in P. humilis than in P. lounsburyi, suggesting that host specificity by P. lounsburyi does not confer a higher efficiency on B. oleae in cultivated olives. Two abiotic factors were shown to impact parasitoid efficiency. First, adult parasitoid survival was poor during periods of high summer temperatures, common to the olive production areas in California's interior valleys. Second, parasitism levels were lower on B. oleae larvae feeding in larger Ascolano cv. fruit than in smaller Manzanillo cv. fruit. Results are discussed relative to biological control of B. oleae in commercial olives and the usefulness of natural enemies specialized to attack fruit flies in wild olives compared with the larger cultivated olive fruit.

Evaluation ofDiachasmimorpha longicaudata(Hymenoptera: Braconidae) as a mortality factor ofCeratitis capitata(Diptera: Tephritidae) infestingCitrusspecies under laboratory and field-cage conditions

“…For instance, the parasitoid females we tested were able to reach C. capitata larvae located up to 8.5 mm below the C. sinensis fruit surface (Laura Bezdjian, personal observation). It is recognised that the length of a parasitoid's ovipositor may restrict its effectiveness in locating and parasitizing larvae feeding deep inside the fruit (Leyva et al 1991;Lopez et al 1999;Sivinski et al 2001;Wang et al 2009a, Wang, Johnson, Yokoyama, Pickett, andDaane 2011).…”

Courtship and mating behaviour in the fruit fly parasitoid Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae): the role of wing fanning

“…It was first found in Tunisia on olive fruit fly (Marchal 1910), and subsequently has been used in several Mediterranean areas for the biological control of this pest (Tzanakakis 2006; Daane and Johnson 2010). Recently, P. concolor has been released in Californian olive-groves as part of classical biological programmes to control olive fruit fly Wang et al 2010). Studies of the mating behaviour in related species of Braconidae have added to our understanding of courtship displays, and the temporal patterning of behaviour and communication with chemical and physical signals (Rungrojwanich and Walter 2000;Danci et al 2010;Joyce et al 2010).…”

Impact of mass-rearing on the host seeking behaviour and parasitism by the fruit fly parasitoid Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae)

“…This parasitoid has been used in Italy and other Mediterranean areas for the biological control of B. oleae by inundative and propagative releases (for a synthesis see Tzanakakis 2006; Daane and Johnson 2010). It has recently been released in Californian olive-groves as a part of classical biological control programmes (Yokoyama et al 2008;Wang et al 2009;Daane and Johnson 2010;Wang et al 2010).…”