Suppression of Residual Populations of Stored-Product Pests in Empty Corn Bins by Releasing the Predator Xylocoris flavipes (Reuter)

Populations of stored grain pests infesting grain residues in empty corn bins were affected differently by releases of 50 pairs of the predatory warehouse pirate bug, Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae). Large insects, such as late instar pyralid moth larvae and adults, apparently were unaffected by the releases. Also, species such as the Sitophilus weevils and the lesser grain borer that develop in grain kernels were much less affected than small externally feeding insects. However, populations of a wide variety of species of small beetles, including both direct grain feeders (Tribolium castaneum, Oryzaephilus surinamensis, and Cryptolestes spp.) and secondary feeders (Ahasverus advena, Typhaea stericorea, and Carpophilus dimidiatus) were either greatly reduced or eliminated by X. flavipes. Populations of these species had been reduced by 70 to 100% at the termination of the tests. Our results showed that residual populations of several species of small beetles in empty grain bins can be greatly reduced by weekly releases of a small number of X. flavipes. If specific parasitoids for moths and the primary grain pests were also released, the whole pest complex inhabiting empty grain bins might be greatly reduced or eliminated before newly harvested grain is brought to the bins for storage. (C) 1992 Academic Press, Inc.