The role of Brachyufens osborni (Hymenoptera: Trichogrammatidae) in the classical biological control program against Diaprepes abbreviatus (Coleoptera: Curculionidae) in Florida

Brachyufens osborni is an indigenous egg parasitoid of weevil species laying concealed eggs in Florida. Diaprepes abbreviatus, an exotic weevil pest of different crops in the southern USA, has been reported as a host for B. osborni. In this study we investigated the interaction between B. osborni and D. abbreviatus as well as other hosts including Pachnaeus litus and Artipus floridanus. The thermal requirements of B. osborni and the interaction between this species and three other weevil parasitoids introduced in a classical biological control program against D. abbreviatus (Aprostocetus vaquitarum, Haeckeliania sperata and Quadrastichus haitiensis) were also examined in laboratory studies. Although B. osborni attacked eggs of all weevil species tested, it could not complete development on D. abbreviatus. The three exotic parasitoids did successfully develop on both P. litus and D. abbreviatus eggs, though our results showed that P. litus should not be considered as an alternative host for the introduced parasitoids during winter in central Florida. Because B. osborni cannot complete development on D. abbreviatus, it has never been recovered from field collected hosts, and its effect on D. abbreviatus in the field remains ignored. This study demonstrates that although B. osborni could not successfully develop in D. abbreviatus, it can inflict important mortality to it and suggests that B. osborni could impact the establishment of introduced D. abbreviatus egg parasitoids. [copyright] 2010 Elsevier Inc. All rights reserved.