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

Pest fly larvae and adults (Musca, Fannia spp.) and key predator arthr opods (Macrocheles mites, Carcinops adults and Histeridae larvae, Stap hylinidae larvae) were monitored for 2 yr on 3 southern California cag ed-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 (A lternate). After 1 mo the remaining rows of manure were removed in the Alternate houses. In each cycle the manure fauna was sampled before r emoval, 1 wk after initial removal, 4 wk after initial removal (before secondary removal in Alternate houses), and 8 wk after initial remova l (4 wk after secondary removal in Alternate houses). Cleanout caused significant decreases in key predator taxa 1 wk afterward and increase d numbers of pest flies for 1-2 mo. Cleanout between March and May usu ally resulted in a resurgence of Fannia spp., whereas late summer clea nouts could cause M. domestica problems. Presence of undisturbed manur e within the Alternate houses did no result in increased numbers of pr edaceous Coleoptera in nearby disturbed manure relative to Normal hous es. Numbers of Macrocheles in disturbed manure after cleanout were hig her when undisturbed manure was immediately adjacent. Pest flies follo wing a cleanout were not reduced in Alternate houses relative to Norma l houses. In these open-sided poultry houses, which leave a dry base m anure pad at cleanout, any slight advantage of fly control afforded by alternate manure removal probably is overshadowed by the increased ti me and effort involved.