The impact of rotational hog grazing on non-targets in apple orchards

Rotationally grazing hogs in tree fruit orchards has been found to provide partial management of plum curculio Conotrachelus nenuphar (Herbst), codling moth Cydia pomonella, and Oriental fruit moth, Grapholita molesta (Busck). These species spend part of their life cycle in the soil and in dropped fruit, both of which are disturbed by hogs. In this study, we investigated whether or not hogs also impact non-targets, including insects, earthworms, and other arthropods. The experiment consisted of three control plots and three grazed plots of 2 acres each that were randomly selected and established in a Michigan apple orchard. In grazed plots, twenty-four Berkshire hogs were rotationally grazed during June and July of 2012 and 2013. Twelve sampling points were established in each plot. At each sampling point, we sampled arthropods using pitfall traps and sticky cards. Earthworms were sampled by hand sorting and applying a hot mustard vermifuge. In 2012, we sampled once before hogs entered plots and once after hogs were grazed. In 2013, we sampled prior to hogs, during hogs, and after hogs. All organisms were taken back to the lab, preserved, quantified, and identified at least to the family level. Hogs did not significantly impact the abundance of any non-target taxa sampled, and thus likely do not reduce ecosystem services provided by those that are beneficial organisms.