D3160: Potato leafhopper resistant alfalfa plots have fewer natural enemies than non-resistant alfalfa

A common set of cultivars resistant to the potato leafhopper (PLH) employ glandular trichomes and stems and petioles. Though this resistant alfalfa suffers less from PLH, it may experience greater injury from other pests like aphids and alfalfa weevil. This suggests that the resistant cultivar may affect non-target species. Biological control agents, like parasitoid wasps and coccinellids, may be less abundant in resistant alfalfa, allowing pest populations to rise to economic levels. We aim to compare natural enemy numbers and species diversity across near isolines of resistant and non-resistant alfalfa. Here, we planted eight 50x50 foot plots of Pioneer 55V50 (susceptible) and 55H96 (resistant) in 2022 at Central Maryland Research and Education Center, Clarksville, MD. Each plot is sampled between April and August with sticky traps, sweep samples, and D-vac. In addition, stem samples are measured and weighed to assess the growth and health of the alfalfa. Finally, the alfalfa is sampled at harvest for yield. Results from 2022 show a slight dip in overall natural enemy abundance in resistant alfalfa plots. Heteroptera and Hymenoptera seemed to be the most affected. Data from 2023 are still being collected. This study will shed light on how host plant resistance and biological control agents interact with each other.