Robert J. Orpet

Pear psylla, Cacopsylla pyricola (Förster), is a key pest of pears in the Pacific Northwest United States. Overwintering adults (winterforms) recolonize orchards in late winter from habitat outside orchards. To reduce winterform colonization and subsequent damage, sprays of the repellent particle film, kaolin clay, are recommended from late dormant through bloom. However, many pear growers struggle to make early sprays due to the danger of driving tractors over hilly terrain with lingering winter moisture. To address this challenge, we tested fall applications of kaolin (Surround WP) for suppression of pear psylla the following spring. Experiments were performed on potted trees and commercial orchard-sized plots, with fall kaolin treatments made at 112 kg/ha (120 g/L). Pear psylla adult and egg densities were measured by visual counts, and kaolin residue stability was assessed by relative whiteness of branches using ImageJ. In the days immediately after kaolin applications (fall and spring), kaolin significantly reduced pear psylla adult numbers and increased branch whiteness. Fall kaolin residues visibly declined over the winter, but branches often remained significantly whiter than checks at spring assessments. Likewise, fall kaolin often resulted in significantly fewer adults and eggs than checks the following spring. This study demonstrates that residues from fall-applied kaolin can remain through the winter and reduce pear psylla colonization the following spring. This tactic will be advantageous in orchards that are difficult to spray in early spring, and as a general addition to the pear integrated pest management toolkit.

A recent outbreak of X-disease, caused by the phytoplasma “Candidatus Phytoplasma pruni,” has severely harmed stone fruit production in the Pacific Northwest region of the United States. X-disease is spread by leafhopper vectors, primarily Colladonus montanus reductus in Washington and Euscelidius variegatus in Oregon. Growers rely on frequent insecticide applications and removal of infected trees, but these management recommendations originate from California when the last outbreak occurred in the 1980s. To update insecticide efficacy information for X-disease vectors, we evaluated 23 commercially available insecticidal products via direct spray, spray residues, systemic uptake by plants, or repellency assays. In direct spray bioassays, insecticides containing pyrethrins, pyrethroids, neonicotinoids, or organophosphates caused 100% mortality of C. m. reductus after 24 h. More selective chemistries including cyantraniliprole, flonicamid, and botanical essences also caused high mortality (>70%) of C. m. reductus (Van Duzee). For residues, neonicotinoids and pyrethroids caused the greatest mortality (≥70%) of C. m. reductus. Systemic uptake of neonicotinoids caused significantly higher mortality (51.4% to 100%) than controls (1.4% to 32.4%) of C. m. reductus. Direct sprays and 5 d residues of neonicotinoids caused high mortality (>70%) of E. variegatus. Cherry leaves treated with either kaolin clay or diatomaceous earth had 80% to 90% fewer C. m. reductus residing on them than the controls. Overall, pyrethroids and neonicotinoids were the most effective, but more selective chemistries and repellent clays showed potential and need to be validated in field conditions. Future work should integrate insecticides, repellents, and cultural tactics with phenology-based treatment timings to improve management sustainability.

The European earwig, Forficula auricularia L. (sensu lato), has a dual role in temperate tree fruit crops—a pest of stone fruit and a predator of key pests in pome fruit. Some growers trap earwigs in crops where they are pests, subsequently releasing them in pome fruit as an augmentative biological control strategy. Effective earwig monitoring and trapping are critical for understanding their biological control potential in orchards. Traps made of rolled, corrugated cardboard have long been used for earwig monitoring; however, no standardized studies have investigated improvements to them. In a series of trials, we explore options to improve traps by testing different trap materials, sizes, positioning on the tree, and time in the field, in addition to the lures and baits. We found that cardboard traps had higher earwig catch than black or translucent plastic traps. There were diminishing returns in earwig capture for increased trap length, plateauing at ~30 cm. Traps placed on the main trunk captured more earwigs than traps on the base or near the end of branches. Lures and baits mostly did not increase trap efficacy, except fish sauce which inconsistently increased earwig captures. The use of plastic bottles to contain the cardboard traps greatly reduced trap catch. Finally, we found evidence that traps left in the field for longer periods of time can increase earwig capture, possibly due to the accumulation of earwig aggregation pheromone. Overall, the standard unbaited corrugated cardboard trap was the most effective and practical earwig monitoring trap.

European earwig, Forficula auricularia L. sensu lato (Dermaptera: Forficulidae), is a univoltine, resident, omnivorous species and a beneficial predator in pome fruit orchards. Here, three methods were used to investigate pear (Pyrus communis L., Rosaceae) orchard inoculation with European earwig for biocontrol of pear psylla, Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae), in Washington State, USA. The first method was earwig inoculation experiments. In a first experiment (2019–2020), each of three orchards had one inoculation and one control plot. In a second experiment (2020–2021), there were four inoculation and four control plots in each of the same three orchards. In both experiments, earwigs persisted during the year of inoculation, but earwigs were nearly absent the following season at two orchards that used conventional broad‐spectrum pesticides. At the third orchard, which excluded broad‐spectrum pesticides under an integrated pest management (IPM) program, earwigs became abundant in year two of the second experiment. The second method was case studies. In the first of two case studies, during 2016, 2017, 2022, and 2023, in half of the integrated orchard from above, conventional broad‐spectrum sprays were used. Earwig populations became low in the conventional half. In the second case study, earwigs became abundant after inoculation of an integrated orchard by the grower. Earwigs spread to the edge of the orchard in year two and spilled into a neighboring orchard in years three and four. The third method was an observational study of 36 pear orchards over 5 years. Earwigs were rarely found in conventionally sprayed orchards, and earwigs increased each additional year integrated management was used. The findings suggest conventional pear spray programs in Washington nearly eradicate earwigs, but populations can recover under integrated management with natural dispersal from refuges or with inoculative releases.

The objective of this slide-dip bioassay was to compare effects of TetraCURB MAX, AlliCURB MAX, Bexar, and 440 Superior Oil on pear psylla (PP) adults. Experimental units were glass microscope slides with 10 PP adults per slide affixed with double-sided tape (Scotch Brand, product # 6137H-2PC-MP). The PP adults were collected on 20 Jun 2024, by aspirator from beat trays in an untreated pear orchard at Washington State University Tree Fruit Research and Extension Center. The PP were anesthetized with CO₂ in the laboratory for handling, and then 5 random males and 5 females were affixed to each slide. There were 5 replications for all treatment groups. Treatments included a high and low label rate of both TetraCURB MAX and AlliCURB MAX, a high label rate of Bexar, a 50 × rate of Bexar for a positive check, and distilled water for a negative check. Slides were dipped into each treatment solution, gently swirled for 5 s, and dried on racks at 72 °F and 24% relative humidity for 30 min or until dry. Slides were then placed in lidded plastic containers on top of a moist paper towel to prevent desiccation. At 24 and 48 h after treatment, each PP was touched with a paintbrush and classified as dead if there was no movement or were incapable of sustained movement. Within each day of assessment, the number of PP affected was analyzed by ANOVA using the “aov” function in R followed by a Tukey test using the “TukeyHSD” function. In the water treatment, one replication was excluded from analysis due to a damaged PP individual.

The objective of this study was to assess the effects of insecticides, Cinnerate, Ultor, and Bexar, on pear psylla (PP) treated at egg and nymph life stages. In spring 2019, pear seedlings (“Bartlett,” 11.5 cm caliper and 30–40 cm in height) were potted in 9 cm width × 10 cm height pots. On 16 Aug, PP adults were collected from an untreated pear orchard at Washington State University Tree Fruit Research and Extension Center using beat trays and aspirators. Collected PP adults were then anesthetized with CO₂ in the laboratory and sets of 4 female and 2 male PP were enclosed in fine black mesh drawstring bags, which were then secured over each seedling. Seedlings with PP were placed into a greenhouse to oviposit. On 27 Aug, the total PP eggs on each seedling were counted using a handheld magnifying lens. Nymphs and adults were removed, and bags were replaced over seedlings. The seedlings were then separated into 2 groups, one for treating eggs and the other for nymphs.

The European earwig Forficula auricularia (L.) (Dermaptera: Forficulidae) is an omnivorous insect that is considered a minor pest of stone fruit and a key predator of pests in pome fruit orchards. In many pome fruit orchards, earwigs are absent or in low abundance due to broad-spectrum spray programs and the slow recolonization rate of earwigs. Orchards in transition to organic or “selective” conventional programs often struggle to achieve effective levels of biological control, and thus, may benefit from inoculating earwigs to expedite their re-establishment. In a two-year study, we evaluated the potential for mass trapping earwigs from stone fruit using rolled cardboard traps to reduce fruit damage and provide earwigs for augmentation in pome fruit. We also tested whether a single mass release or five releases (on alternating weeks) of the same total number of earwigs in apples and pears reduced pests relative to plots where no releases occurred. Mass trapping did not decrease earwig abundance or substantially reduce fruit damage in stone fruit orchards. However, trapping was an efficient method for providing earwigs for augmentation. Earwig abundances were only increased in orchards where earwigs were previously low or absent; however, multiple orchards with varying prior levels of earwigs exhibited reductions in key pests (woolly apple aphid and pear psylla). For some other pests evaluated, plots with mass releases of earwigs had a slight trend in overall lower pest density when compared with control plots. A strategy for moving earwigs out of stone fruit orchards and into pome fruit orchards could be an effective method for augmenting orchard predator populations.

Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae) is the most expensive and challenging insect pest of commercial pear trees in the Pacific Northwest. Integrated pest management (IPM) programs are working toward relying more heavily on natural enemies to reduce insecticide use. Trechnites insidiosus (Crawford) (Hymenoptera: Encyrtidae) is the main parasitoid of C. pyricola, but little is known about its biology in the region. Developing sampling tools is important for the deployment of IPM programs, including monitoring of natural enemies. In this study, we examined 2 conventional monitoring methods: beat trays and yellow sticky cards, in addition to screened sticky cards and 3D-printed cylinder traps. Additionally, we tested an overwintering trap for the collection of parasitized C. pyricola. The trapping methods were tested in orchards in Oregon and Washington. Unscreened cards caught the most T. insidiosus and C. pyricola, followed by screened cards, cylinder traps, and then beat trays. Beat trays sometimes failed to catch any T. insidiosus, even when it was found in abundance via other methods. Screened cards and cylinder traps reduced bycatch and increased ease of identifying T. insidiosus. Specimens from the cylinder traps were also more suitable for use in molecular analysis. The overwintering traps were effective at capturing parasitized C. pyricola, but were highly variable year to year. The ideal trapping method will vary based on research needs (e.g., DNA preservation, reducing bycatch, catching higher numbers), but both screened sticky cards and cylinder traps were viable methods for monitoring T. insidiosus and its host.

Quantifying gene flow between lineages at different stages of the speciation continuum is central to understanding speciation. Heliconius butterflies have undergone an adaptive radiation in wing color patterns driven partly by natural selection for local mimicry. Color patterns are also known to be used as assortative mating cues. Therefore, wing pattern divergence is considered to play a role in speciation. A corollary is that mimicry between closely related species may be associated with hybridization and interfere with reproductive isolation. Here, we take a multifaceted approach to explore speciation history, species boundaries, and traits involved in species differentiation between the two closely related species, Heliconius hecale and Heliconius ismenius. We focus on geographic regions where the two species mimic each other and contrast this with geographic regions where they do not mimic each other. To examine population history and patterns of gene flow, we tested and compared a four-population model accounting for linked selection. This model suggests that the two species have remained isolated for a large part of their history, yet with a small amount of gene exchange. Accordingly, signatures of genomic introgression were small except at a major wing pattern allele and chemosensing genes and stronger in the mimetic populations compared with nonmimetic populations. Behavioral assays confirm that visual confusion exists but that short-range cues determine strong sexual isolation. Tests for chemical differentiation between species identified major differences in putative pheromones which likely mediate mate choice and the maintenance of species differences.