Impact of Alternating Manure Removal Schedules on Pest Flies (Diptera: Muscidae) and Associated Predators (Coleoptera: Histeridae, Staphylinidae; Acarina: Macrochelidae) in Caged-Layer Poultry Manure in Southern California

Abstract

Pest fly larvae and adults (Musca, Fannia spp.) and key predator arthropods (Macrocheles mites, Carcinops adults and Histeridae larvae, Staphylinidae larvae) were monitored for 2 yr on 3 southern California caged-layer poultry facilities. In each manure cleanout cycle, all manure rows were removed initially in normal removal houses (Normal), while half of the manure was left undisturbed in alternate removal houses (Alternate). After 1 mo the remaining rows of manure were removed in the Alternate houses. In each cycle the manure fauna was sampled before removal, 1 wk after initial removal, 4 wk after initial removal (before secondary removal in Alternate houses), and 8 wk after initial removal (4 wk after secondary removal in Alternate houses). Cleanout caused significant decreases in key predator taxa 1 wk afterward and increased numbers of pest flies for 1-2 mo. Cleanout between March and May usually resulted in a resurgence of Fannia spp., whereas late summer cleanouts could cause M. domestica problems. Presence of undisturbed manure within the Alternate houses did not result in increased numbers of predaceous Coleoptera in nearby disturbed manure relative to Normal houses. Numbers of Macrocheles in disturbed manure after cleanout were higher when undisturbed manure was immediately adjacent. Pest flies following a cleanout were not reduced in Alternate houses relative to Normal houses. In these open-sided poultry houses, which leave a dry base manure pad at cleanout, any slight advantage of fly control afforded by alternate manure removal probably is overshadowed by the increased time and effort involved.