Auchenorrhyncha (Hemiptera) includes several families of sap-feeding insects that tend to feed on a wide-range of host plants. Some species within Auchenorrhyncha are major agricultural pests that transmit plant pathogens or cause direct feeding damage. Nearly all pest Auchenorrhyncha are highly polyphagous, have mobile nymphs, and colonize crops from noncrop habitats. We examined whether methods for gut content analysis developed for more specialized Hemiptera identify dietary history of polyphagous Auchenorrhyncha. We used high-throughput sequencing of the plant genes trnF and ITS to examine the dietary history of Circulifer tenellus (Baker) (Cicadellidae), Colladonus geminatus (Van Duzee) (Cicadellidae), Colladonus montanus reductus (Van Duzee) (Cicadellidae), and Lycorma delicatula (White) (Fulgoridae). C. tenellus is a vector of the vegetable pathogens Candidatus Phytoplasma trifolii and beat curly top virus. Both Colladonus species are vectors of Ca. Phytoplasma pruni, the pathogen associated with X-disease of stone fruits. Lycorma delicatula is an invasive pest of grape and ornamentals in the eastern United States. Results showed spring hosts for C. tenellus included Brassicaceae, especially Sisymbrium sp. (tumble mustard), and spring hosts for both Colladonus species included Taraxacum sp. (dandelion). Gut content analysis also detected a decrease in host-breadth by L. delicatula from early to late instars. Results demonstrate that directed sequencing of plant DNA identified the dietary history of leafhopper and planthopper pests. Expanded use of gut content analysis will help identify the noncrop sources of phytoplasma-infected C. tenellus and Colladonus, and to examine seasonal changes in host shifts by L. delicatula.

Management of direct apple pests, such as codling moth, continues to be problematic despite the widespread implementation of behavioral and chemical controls. Apple growers have increased their use of netting to protect fruit from environmental injury, with some structures enclosing the entire orchard. These enclosures represent a new pest management tactic through physical exclusion. We conducted a two-year trial to examine the effects of full exclusion netting on pests and natural enemies of apples. Insect densities and damage in trees under fully enclosed (net) cages were compared with conventionally (insecticide only) treated and untreated plots. Caged plots had 18.1- and 11.4-fold less codling moth damage than the check, and 4.9- and 4.2-fold less damage than the insecticide-only plots in 2016 and 2017, respectively. However, densities of woolly apple aphid and its parasitoid Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) were significantly greater in the caged plots. Densities of earwigs, a typically flightless generalist predator, were not different among treatments, while adults of more mobile flying generalist predators, lacewings and syrphids, were significantly lower in cages compared with uncaged plots. These results demonstrate that although biological control may be partially disrupted, net enclosures have significant potential as a holistic apple management technique.

1. Apple growers have pursued the use of exclusion netting to reduce pesticide inputs and maintain control of codling moth.2. It is uncertain if these nets provide a physical or behavioural behaviour, and if they prevent codling moth establishment.3. To address this, we conducted field trials testing the ability of commercial netting to exclude codling moth using small (3 trees) and large (48 trees) cages. Experiments were conducted to evaluate both the permeability by releasing marked sterile moths either inside or outside the small cages, and the establishment of wild codling moth in the large cages.4. Results from the small cage study showed that netting reduced codling moth movement out of the netted plots, but virtually prevented codling moth dispersal into the plots. Codling moth capture inside the large cage plots was significantly less than in uncaged plots, but no differences were found in codling moth damage at harvest. 5. These results indicate that the netting is physically permeable to codling moth adults; however, it acts as a behavioural barrier to moth immigration. These outcomes agree with existing literature that net enclosures can provide a noninsecticidal tool to improve codling moth management, although it may not be a stand-alone technique.