Parasitoids and hyperparasites of citrus aphids in northern east of Tunisia (Cap Bon)

Abstract: A field survey of parasitoids of citrus aphids was undertaken in the Cap Bon region (northern east of Tunisia) during the years 2010 and 2011. Four citrus orchards (2 organic farming orchards, 2 conventional farming orchards) were sampled every 15 days during the two years. Aphid mummies were collected from young shoots. Citrus were attacked by five species of aphids, Aphis gossypii (Glover) Aphis spireacola (Pagenstecher), Toxoptera aurantii (Boyer), Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas). Five species of primary parasitoids were collected, Lysiphlebus testaceipes (Cresson), Lysiphlebus fabarum (Marshall), Binodoxys angelicae (Haliday), Aphidius matricariae (Haliday) and Aphidius colemani (Viereck). Six species of hyperparasites were also identified, Pachyneuron aphidis (Bouché), Pachyneuron muscarum (L.), Asaphes vulgaris (Walker), Asaphes suspensus (Nees), Phaenoglyphis villosa (Hartig) and Alloxysta victrix (Westwood). All the hyperparasites were identified to species for the first time in Tunisia. Lysiphlebus testaceipes was, by far, the dominant species of primary parasitoids in term of frequency in all the studied sites, while Pachyneuron aphidis was the dominant species of hyperparasite. The survey of parasitism rate in the first organic farming (site A) shows that it reached 14 and 17% in 2010 and 2011 in the period of May-June. The diversity Shannon index (H’) in the different study sites ranged from 1.5 to 1.88 depending on the locality.