Combining larval parasitoids and an entomopathogenic fungus for biological control of Sitophilus granarius (Coleoptera: Curculionidae) in stored grain

The potential of combining different natural enemies for biological control of Sitophilus granarius (L.) in grain was investigated in a laboratory study. We compared the effect of two species of larval parasitoids, Lariophagus distinguendus Förster and Anisoptermalus calandrae (Howard), alone or in combination with a surface treatment of the grain with the entomopathogenic fungus Beauveria bassiana (Bals.) Vuillemin against S. granarius in units containing 9 kg of wheat over a period of 26 weeks. In the untreated units, the pest population increased about 5000 times. The highest level of pest suppression (>99.9%) was obtained in units with L. distinguendus, followed by units with A. calandrae. In units with both parasitoids and the entomopathogen, the pest suppression level was 83–98%. Although the parasitoids were negatively affected by the fungus, they still exerted some degree of control compared to the untreated units.