Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2007
Publication Date: 2/1/2008
Citation: Sing, S.E., Arbogast, R.T. 2008. Optimal Xylocoris flavipes (Reuter) (Hemiptera:Anthocoridae) density and time of introduction for suppression of bruchid progeny in stored legumes. Environmental Entomology. 37(1):131-142. Interpretive Summary: The need to reduce the risk posed by chemical pesticides to human health and the environment, and at the same time to protect food commodities from damage and contamination by insect pests, has prompted a substantial research effort to develop insect control strategies that reduce or eliminate the need for chemical application. Biological control using other insects that feed upon pest species (natural enemies) is one such control strategy that has received much attention and has shown considerable promise. Scientists at Montana State University, in cooperation with ARS scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida, have found that the warehouse pirate bug, a natural enemy that preys upon a wide range of stored food pests, offers an especially promising means of controlling a variety of bean weevils. These weevils, which infest dry beans during storage, cause serious economic loss by consuming and contaminating the beans. The research showed that the degree of weevil control depends upon the number of warehouse pirate bugs used, but that relatively low levels of introduction are needed. The research also showed that the predators should be introduced as soon as possible after the beans are placed in storage. The information provided by this study will be used by scientists to develop biological, chemical-free methods that can be used by farmers and warehouse operators for reducing losses caused by these weevils.
Technical Abstract: The influence of both predator density and elapsed time between initial infestation and introduction of predators were determined for suppression of bruchids infesting stored grain legumes by Xylocoris flavipes (Reuter)(Hemiptera: Anthocoridae). Suppression of Acanthoscelides obtectus approached eradication with all predator treatments. For all other bruchid species evaluated (Callosobruchus analis, C. chinensis, C. maculatus and Zabrotes subfasciatus), the most effective predator density and addition time (5 predator pairs at 0 h) resulted in an approximate 50% reduction of emerging F1 bruchids compared to progeny produced in untreated arenas. The predator addition time of 0hr, when predators were added to experimental arenas simultaneously with the pest species, was determined to be the universally most efficacious treatment time. Predator density above 1 pair but lower than 5 pairs was less influential overall when X. flavipes was added 24 or 120 h after initial bruchid infestation; however, maximum suppression was achieved at approximately 2 predator pairs and not significantly improved upon with increased predator density. Our results indicate that the most effective biological control of pest bruchids would occur when X. flavipes is added as soon as possible after legumes are stored.