Volume 57: 2025 - Hawaiian Entomological Society

Permanent URI for this collectionhttps://hdl.handle.net/10125/110132

Browse

Recent Submissions

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item type: Item ,
  • Thumbnail Image
    Item type: Item ,
    Irradiation of Melon Fly, Zeugodacus cucurbitae (Diptera: Tephritidae), in Artificially versus Naturally Infested Papayas
    (2025-10-09) Peter A Follett
    Many fruits are naturally rarely infested by their quarantine pests or are poor hosts for larval development and may require manipulation during quarantine treatment development to achieve infestation. This study compared the effects of artificial versus natural infestation on melon fly, Zeugodacus cucurbitae (Cocquillet) (Diptera: Tephritdae), survival in papaya after irradiation. Papayas were infested either by inserting third instar larvae through a bore hole into the center of the papaya (artificial infestation) or by exposing fruit to adult oviposition in small cages and raising larvae to third instar (natural infestation). Infested fruit were then irradiated at 40 Gy and held for adult emergence. Mean adult emergence was higher in artificially (7.6%) than naturally (0.6%) infested papayas after irradiation, but the difference was non-significant. The advantages to artificially infesting fruit during quarantine treatment studies are discussed.
  • Thumbnail Image
    Item type: Item ,
    Evaluating the Persistence of Pyrethrin and Pyrethroid Insecticides in Coconut Palm (Cocos nucifera) Canopies for Coconut Rhinoceros Beetle (Oryctes rhinoceros) Management
    (2025-08-07) Xing Wei; Tomie Vowell; Scott Nikaido; Jordie Ho; Alexandra Kong; Keith Weiser; Daniel Jenkins; Michael Melzer
    Canopy application of contact insecticides is emerging as a short-term tool for protecting against coconut rhinoceros beetles (CRB; Oryctes rhinoceros) in Hawai‘i. Pyrethrin and pyrethroid formulations are primarily labeled for use on ornamental plants, which represent a large portion of Hawaiʻi’s public palms. To provide guidance on the frequency for which insecticides should be applied, we evaluated five products with labeling that allowed applications to coconut palm crowns as ornamentals and/or fruit production in Hawaiʻi. Burlap was soaked in spot-treatment or minimum-volume per area rates according to product labels, with water as the control. After drying, burlap was used immediately in bioassays or affixed to coconut palm canopies at a research station in Mānoa Valley, Oʻahu, exposed to local weather. Sub-samples were collected every four weeks for bioassays, where 4 to 5 g of treated burlap was placed in a perforated 500-mL bottle with four colony-reared adult CRB added (12 total per treatment). After a 24-h exposure, insect health was rated on a 5-point scale (1 = dead, 5 = healthy) via double-blind evaluation. CRB ratings were analyzed using KruskalWallis and Dunn’s tests with Bonferroni correction. Burlap treated with synthetic pyrethroids deltamethrin, prallethrin and lambda-cyhalothrin, cypermethrin, and zeta-cypermethrin retained toxicity against CRB for at least 12 weeks. The organic pyrethrins did not retain toxicity. Since many palms in Hawaiʻi are routinely serviced by arborists and landscapers every 3 to 5 months, a canopy application of the longer-lasting formulations may serve as an immediate management option for protecting palms from CRB.
  • Thumbnail Image
    Item type: Item ,
    Abundance of ʻŌhiʻa-Associated Ambrosia Beetles in Two Sites with Rapid ʻŌhiʻa Death Outbreaks
    (2025) Sofaer, Helen R.; Smith, Sophia M.; Peck, Robert W.; Dunkle, Ellen J.; Zarders, Jorden A.; Odachi, Naiʻa; Perroy, Ryan
    ʻŌhiʻa lehua (Metrosideros polymorpha Gaudich.) is the dominant tree in native Hawaiian forests but is threatened by two pathogenic fungi (Ceratocystis spp.) which cause Rapid ʻŌhiʻa Death (ROD). Understanding the spread of ROD is vital to informing prevention and management strategies. Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) contribute to the spread of disease by releasing contaminated frass into the environment or carrying fungal spores between trees on their bodies. We quantified the abundance of ʻōhiʻa-associated ambrosia beetles and their potential contributions to fungal spread within two study sites experiencing active ROD outbreaks. We established a grid of beetle traps at each site, cultured trap samples for viable Ceratocystis, and compared the spatial distribution of beetle captures with that of ʻōhiʻa trees showing symptoms of ROD. Nearly all captured ʻōhiʻa-associated beetles were Xyleborinus saxesenii (Ratzeburg) or Xylosandrus crassiusculus (Motschulsky), both introduced species that utilize many plant hosts. For both species, abundance was unrelated to distance to the nearest symptomatic ʻōhiʻa tree. However, at one of our sites, Xylosandrus crassiusculus abundance was higher on one side of a fence line, where there were more symptomatic ʻōhiʻa within a denser and more diverse forest. Culturing the collected samples (beetles, water, and debris) produced instances of Ceratocystis viability in samples both with and without ʻōhiʻa-associated beetles, supporting the potential for transmission via frass carried by wind as well as direct transmission by beetles. The community of ʻōhiʻa-associated beetles we captured differed from previous findings at lower elevation sites, highlighting the complexity of beetlemediated fungal infection risk.
  • Thumbnail Image
    Item type: Item ,
    Hylaeus (Nesoprosopis) paumako (Hymenoptera: Colletidae), a New Endemic Bee from Molokaʻi, Hawai‘i
    (2025) Magnacca, Karl N.
    Hylaeus paumako new species, a new native bee from dry-mesic forest on Molokaʻi, is described. This is the first new bee species discovered on Molokaʻi in over 100 years, and the first from Molokaʻi where males lack colored facial marks. It was taken in company with H. connectens and H. laetus, both of which also had not been seen on the island for decades.