Habitat management to enhance biological control in cultivated crops is increasingly used for pest control in annual and perennial systems. Approaches include windbreaks or hedgerows to build natural enemy populations around crop edges, insectary seed mixes as cover crops, and management of ground cover (via mowing, strip mowing, or selective herbicide use) to support natural enemies. These strategies aim to provide predators and parasites with alternative habitats and food sources, hoping they will move into the crop to curb pest damage. Alternative food sources may include flowering plants and non-crop host arthropods, although ensuring they do not attract pests can be challenging.

The interaction between ground cover and pear trees in low-pesticide and organic orchards is not well understood, particularly regarding ground cover as a source of natural enemies. The study aims to determine whether mowing frequency affects natural enemy densities in ground cover and pear trees in mating disruption and organic orchards.

Project Objectives:

1. Assess the effects of mowing frequency on the density and diversity of pest and beneficial arthropods on the orchard floor, in the ground cover, and on the pear tree

2. Estimate the impact of beneficials on pear pests across mowing regimes (i.e., parasitism and predation rates).

Reduced mowing frequency resulted in significant increases in natural enemy densities in the ground cover, likely due to greater availability of pollen, nectar, and small prey like aphids. Key taxa with increased densities included lacewing larvae, spiders, damselbugs, parasitoids, ladybug beetles, syrphid flies, and minute pirate bugs. Ground-dwelling predators, such as ground beetles and harvestmen, were less affected by mowing frequency, showing slight reductions in less frequently mowed plots. In pear trees, counts of spiders and parasitoids were higher in less frequently mowed areas, while spider mite densities were greater in less frequently mowed plots. Lygus spp. and stinkbugs associated with ground cover increased as mowing frequency decreased, but neither pest was present in damaging numbers on pear tree samples. Density differences among blocks within orchards were substantial, overshadowing smaller differences caused by mowing treatments. Factors such as tree age and block location significantly influenced predator densities.

Although mowing frequency notably affected natural enemy densities, its impact on orchard pests remains unclear. Parasitism rates of pear psylla nymphs showed no effects of mowing treatment, possibly due to consistently low rates (<10%). Monitoring predation rates of codling moth larvae indicated no effects of mowing frequency, though strips were monitored for only 48 hours, limiting results. A positive correlation between larval disappearance rates and earwig densities suggests earwigs may prey on codling moth larvae. The impact portion of the study will be repeated next year at the same sites with improved methodologies and larger sample sizes.