Comparative suitability of Diaprepes abbreviatus and Pachnaeus litus eggs (Coleoptera: Curculionidae) as hosts for Brachyufens osborni (Hymenoptera: Trichogrammatidae): Implications for their biological control

• Brachyufens osborni is a Floridian indigenous Trichogrammatid parasitoid.
• Diaprepes abbreviatus is an exotic pest weevil in Florida.
• B. osborni cannot complete development in D. abbreviatus eggs.
• Eggs of D. abbreviatus display a defensive reaction against B. osborni immature stages.
• The defensive reaction is cellular in nature.

A classical biological control program was initiated in Florida USA in 1997 against Diaprepes abbreviatus (L.) (Coleoptera: Curculionidae), an exotic root weevil. Florida citrus trees are affected by other weevil pests, i.e., Pachnaeus spp., which have their own indigenous parasitoid fauna. One of these parasitoids, Brachyufens osborni (Dozier) (Hymenoptera: Trichogrammatidae), recognized and accepted D. abbreviatus eggs for oviposition. However, it failed to develop in these eggs. The eggs of this weevil display a physiological defensive response against B. osborni immature stages that prevents development beyond the second larval instar. This response though does not occur in the indigenous Pachnaeus litus Germar. The defensive response was likely cellular in nature.

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