Climate Extremes, Vegetation Change, and Decoupling of Interactive Fire-Grazing Processes Exacerbate Fly Parasitism of Cattle.
We assessed local horn fly (Haematobia irritans L.) and face fly (Musca autumnalis De Geer) communities on cattle in 2012 and 2013 relative to vegetation and climate data to understand how parasitism of cattle is influenced by change in climate and vegetation structure. We compared heterogeneity management using spatially and temporally discrete fires (i.e., patch-burning one-third of a pasture annually) to homogeneity management (i.e., burning entire pasture in 2012 then no burning in 2013), with cattle grazing all years in both treatments. Predicted emergence of horn flies and face flies was 24 and 34 d earlier in 2012 associated with earlier spring warming, a significant deviation from the five-year mean. Intraannual horn fly dynamics were explained by concurrent high ambient air temperature the day of observations, but face flies were explained by low ambient air temperatures and dry conditions 3 wk before observations. Importance values of information for the theoretic models including fire treatments ranged from 0.89 to 1, indicating that both horn flies and face flies are sensitive to habitat alterations and fire-driven animal movements. Ordination indicates herds on unburned pastures were dissimilar to herds on pastures burned with patchy fires or pastures burned completely and species-specific fly responses to different vegetation structure metrics. For example, horn flies were correlated with vegetation visual obstruction, and face flies were correlated with woody plant cover. Vegetation structure may be as important as climate in driving the dynamics of fly parasites of cattle.
Department of Ecosystem Science and Management, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071 (jscasta@uwyo.edu).
John D
JD
Scasta
Department of Entomology and Plant Pathology, Oklahoma State University, 102 Agricultural Hall, Stillwater, OK 74078 (justin.talley@okstate.edu).
Justin L
JL
Talley
Department of Natural Resource Ecology and Management, Oklahoma State University, 102 Agricultural Hall, Stillwater, OK 74078 (david.engle@okstate.edu).
David M
DM
Engle
Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 251 Bessey Hall, Ames, IA 50010 (debinski@iastate.edu).
Diane M
DM
Debinski
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000469:parasitology; D057231:Climate Change; D017753:Ecosystem; D005260:Female; D005390:Fires; D007484:Iowa / Q000453:epidemiology; D009117:Muscidae / Q000502:physiology*; D012621:Seasons; D014887:Weather
community and ecosystem ecology; ecosystem; ectoparasite; habitat management; range entomology