Biological control of Ceratitis capitata (Diptera: Tephritidae) in Tunisia: Introduction and potential establishment of Diachasmimorpha longicaudata (Hymenoptera: Braconidae) in Tunisian citrus orchards

Abstract: The Mediterranean fruit fly (Medfly) Ceratitis capitata (Wiedemann) is a key pest of citrus and many other fruits in Tunisia. During many decades, the suppression of C. capitata in Tunisian citrus orchards relied on calendar broad-spectrum applications of synthetic insecticides, mainly carbamates and organophosphates. More recently, the new European legislations regarding the use of insecticides and their tolerated residues in imported commodities, as well as the emergence of resistance and cross resistance to many commonly used insecticides in Mediterranean populations of C. capitata forced stakeholders to review control strategies adopted against this economic pest. As result, alternative control tactics were introduced and promoted in Tunisia including mass trapping and attract-and-kill techniques leading, when properly applied, to a relative decrease in the frequency of insecticides’ applications. Furthermore, a classic biological control program was initiated through the screening for local natural enemies and by the introduction of available efficient exotic parasitoids. In this context, a larval-pupal parasitoid, Diachasmimorpha longicaudata (Hymenoptera: Braconidae) was introduced from Spain to Tunisia on 2013, its rearing was installed in the entomological laboratory of the higher Agriculture Institute Chott-Meriem, study of the longevity during the different season in the Tunisian climatic conditions and immature development were conducted and releases in open field were carried out in Tunisian citrus orchards. As a result, we proved D. longicaudata capacity to disperse and parasitize C. capitata under Tunisian natural conditions, but it was unable to overwinter. The biological control program should be through inoculative releases during each spring to increase the number of successful overwintering specimens and the mass rearing should be intensified to increase the number of released females.