Droning on about lacewings: Can we make releases work in apple orchards?

Best management practices for conducting releases in orchards are lacking. Lacewings are the most common natural enemy to be purchased and released for pest control in organic apples. In 2021-2024, we tested different lacewing species (Chrysoperla rufilabris, Chrysoperla carnea), life stages (eggs versus larvae), and release methods (drone, cards, sprinkle) for control of aphids. We determined that some of the “C. carnea” we purchased were actually C. plorabunda, depending on the source insectary. Recovery of released lacewings and aphid control varied greatly between trial location and year, in addition to treatment. In general, releases of lacewing larvae appear to be the most effective, with C. rufilabris being the least expensive option for growers. Release timing, in relation to both initial aphid populations and temperature, is critical. Getting the timing correct can be particularly challenging for growers as early season releases will often occur during necessary spray timings for either fire blight or bloom thinning; these sprays may be harmful to released lacewings. Molecular gut content analysis with both universal and species specific primers indicated that released lacewings rarely act as intraguild predators in orchards and frequently test positive for target aphid pests.