Effect of seasonal pyric herbivory on muscid fly populations on cattle gazed in the Kansas Flint Hills

Horn flies, Hematobia irritans irritans (L.), are common blood-feeding ectoparasites that impact cattle health and wellbeing. Blood feeding can result in significant blood-loss, pain and irritation, culminating in reduced production outputs. Historically, prescribed burning has been used for weed suppression, improving forage quality and pest arthropod control throughout the Midwest. Prescribed burning is traditionally preformed seasonally in either the spring, summer, or fall. While the season of burning has been shown to effect plant growth, little is known of the impact on pest arthropods like horn flies. This study aimed to determine if horn fly populations are impacted by the season of which the burning is performed. The Kansas State University Beef Stocker Unit is a 1,000 acre facility consisting of 16 pastures with each being assigned to one burn season (spring, summer or fall). Pastures have been burned consistently in their designated season for the past four years and are stocked equally at 246 pound per acre. Starting two weeks after the cattle were released onto pasture, a long-range DSL camera was used to take photographs of different steers in each pasture for 11 weeks. ImageJ software was used to manually count flies on each of the photographs over the study period. Initial results suggest that burn season does impact the number of horn flies with cattle on summer burned pastures having the highest fly burdens. Understanding the impact of burn timing on arthropod pest burdens can be used by producers to make informed decisions on burn treatment options.