Field performance of the egg parasitoid Trichogramma cacoeciae Marchal (hymenoptera: Trichogrammatidae) following releases against Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae) in two types of oasis in Tunisia

Abstract

This study was carried out in two oases located in the south-west of Tunisia to investigate the efficacy of the oophagous parasitoid Trichogramma cacoeciae against Ectomyelois ceratoniae on date palm trees. The first oasis (Hezoua) is characterized by a cropping system divided into three levels of cultures. In the second oasis (Douz), orchards were based on the monoculture of the Deglet Noor cultivar. Parasitoids were released with three doses 26,000, 36,000 and 46,000 Trichogramma/ha. The impact of Trichogramma releases was evaluated by monitoring the egg parasitism, male catches of E. ceratoniae through pheromone traps, fruit damage during the whole season and fruit infestation at harvest. Trichogramma cacoeciae accomplished higher egg parasitism in Hezoua oasis (19.71 ± 1.02%) as compared to Douz oasis (8.43± 1.03%). Inundative releases of T. cacoeciae in the two oases resulted in varying degrees of pest control and they were not sufficient to limit economic losses.