Browsing by Author "Peck, Robert W."

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    Effectiveness of rapid 'ōhi'a death management strategies at a focal disease outbreak on Hawai'i Island
    (2021-02-03) Roy, Kylle; Granthon, Carolina; Peck, Robert W.; Atkinson, Carter T.
    The ongoing spread of rapid ‘ōhi‘a death (ROD) in the Hawaiian Islands threatens the long-term sustainability of ‘ōhi‘a lehua (Metrosideros polymorpha) forests throughout the state. First identified in the Puna district of Hawai‘i Island in 2014, the disease caused by the novel fungi Ceratocystis lukuohia and Ceratocystis huliohia has now spread island-wide and was recently detected on Kaua‘i, O‘ahu, and Maui. The leading hypothesis for the spread of ROD is through airborne ambrosia beetle frass particles that contain viable Ceratocystis propagules, thus management efforts focus on containing this frass. At the time of this study (2017–2018), the Waipunalei site was the northernmost outbreak of ROD on Hawai‘i Island. The focal nature of the outbreak and accessibility of the location provided the opportunity to monitor the effectiveness of two types of proposed management methods to reduce the airborne spread of potentially infective ambrosia beetle frass: tree felling and insecticide treatments. We placed 23 passive environmental samplers (PES), which monitored for airborne frass and wood particles containing C. lukuohia and C. huliohia in a grid that spanned the outbreak area over 22 weeks. Cross-vane panel traps with 1:1 methanol:ethanol lures were attached to nine of the PES to document wood-boring ambrosia and cerambycid beetle populations during the latter three months of the study. Monitoring with PES began three weeks before management and continued for one month after the last infected trees were felled. Glass microscope slides from the 23 PES were examined for airborne ambrosia beetle frass and wood particles by microscopy. DNA was extracted from the slides and tested by qPCR (quantitative polymerase chain reaction) for C. lukuohia and C. huliohia. We also investigated the correlation of beetle gallery counts with tree height and tested the efficacy of Bifen I/T insecticide (active ingredient: bifenthrin 7.9%) for preventing beetle attacks on the cut surface of ‘ōhi‘a bolts (tree stem sections). Beetle trapping data revealed that the area supports a diverse community of wood-boring beetles, some of which likely attack ‘ōhi‘a and may facilitate the spread of ROD. The number of beetle galleries on felled ‘ōhi‘a trees decreased linearly as tree height increased. We also observed significantly fewer beetle attacks on Bifen I/T treated ‘ōhi‘a bolts than non-treated bolts, but gallery formation nearly ceased in both treated and control bolts by week three. Ceratocystis lukuohia DNA was detected twenty-six times and C. huliohia was detected five times in the PES throughout this study. DNA detections were correlated to frass and wood counts, and the number of felled trees were correlated to wood particle counts but not frass counts. Both the timing and distribution of detections across the sampling grid indicate that tree felling may have reduced airborne detections of Ceratocystis DNA soon after tree felling was completed. A subsequent increase in detections after tree felling ceased may indicate that incomplete removal of infected trees and the appearance of new infections in previously asymptomatic trees could have allowed airborne detections of potentially infectious fungal propagules to once again increase.
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    Efforts to eradicate yellow crazy ants on Johnston Atoll: results from Crazy Ant Strike Teams X, XI, and XII (June 2015-December 2016)
    (2017-06-14) Peck, Robert W.; Donmoyer, Kevin; Scheiner, Katrina; Karimi, Rebekah; Kropidlowski, Stefan
    Efforts to eradicate invasive yellow crazy ants (Anoplolepis gracilipes; YCA) on Johnston Atoll have been continuous since their discovery in 2010. Through 2014, a variety of commercial and novel formicidal baits were tested against the ant, but none proved capable of eradication. More recently, polyacrylamide crystals (“hydrogel”) saturated with a sucrose solution containing the insecticide dinotefuran has been shown to be effective over large areas when applied against YCA alone or sequentially with a protein-based cat food bait. During June 2015–December 2016, Crazy Ant Strike Teams (CASTs) conducted treatment and monitoring efforts across an infestation of about 57 ha on Johnston Atoll. Following three infestation-wide treatments (primarily using hydrogel) during 2015, YCA were reduced 98% and surviving nests became difficult to find. Subsequently, a protocol designed to detect ants at low abundance that combined hand searching with a high density of baited monitoring stations (12 stations/0.25 ha; HST protocol) was employed within a network of 50 x 50 m cells that subdivided the infestation. During 2016 YCA were found at numerous locations using this method and standard grid-based bait monitoring surveys. Overall, 65 cells where YCA were detected, or cells adjacent to detections, were treated with hydrogel or cat food bait. YCA were not detected during four monitoring events each separated by at least one week, on 85% of these cells after 1–3 treatments, but it was necessary to treat several cells 4–7 times before YCA were eliminated. Results from HST searches allowed us to estimate the probability that YCA were detected when present in an area when searched using that method. Based on this probability, it was determined that areas would have to be searched three times without YCA being detected to allow 93% certainty that the ants were absent. The level of certainty increased to 99% when the search was conducted four times and YCA were not found. Overall, the likelihood of eradicating YCA on Johnston Atoll appears high using existing protocols.
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    Hawaiian Hoary Bat (Lasiurus cinereus semotus) Acoustic Monitoring at Hawaii Army National Guard (HIARNG) Installations Statewide
    (2020-01-30) Montoya-Aiona, Kristina M.; Pinzari, Corinna A.; Peck, Robert W.; Brinck, Kevin W.; Bonaccorso, Frank J.
    Acoustic sampling for occurrence of the endangered Hawaiian hoary bat (Lasiurus cinereus semotus) was conducted at 18 “long-term” acoustic monitoring stations on 12 Hawai‘i Army National Guard (HIARNG) installations across the islands of Hawai‘i, Maui, Moloka‘i, O‘ahu, and Kaua‘i between 2012 and 2018. Bats were confirmed as present at 10 of these installations: Kealakekua Armory, Keaukaha Military Reservation (KMR), Hanapēpe Armory, Kekaha Firing Range (KFR), Pu‘unēnē Training Facility, Ukumehame Firing Range (UFR), Kaunakakai Armory, Bellows Regional Training Institute, Kalaeloa, Barber’s Point, and the 487th Military Parking Facility, Wahiawā. Seasonal frequency of bat detection was similar to previous acoustic studies for the islands of Hawai‘i, Maui, and O‘ahu. Hawaiian hoary bats were recorded at HIARNG installations during periods of pregnancy, lactation, and pup fledging. Our acoustic sampling did not record bat vocalizations at Fort Ruger and Waiawa Armory. Foraging activity was observed at nine acoustic monitoring stations on the islands of Hawai‘i, Kaua‘i, O‘ahu, and Maui. No foraging activity was observed on Moloka‘i and a single station on O‘ahu recorded one feeding buzz in September 2017 at Kalaeloa, Barber’s Point. Within-night detections showed bat activity was mostly confined to the first six hours of the night but was also variable among stations. In addition to long-term bat acoustic monitoring at HIARNG installations, Hawaiian hoary bat insect prey sampling with paired acoustic monitoring was conducted at KMR on Hawai‘i Island from May through August 2018. Insect abundance and bat activity were sampled within areas where goats and sheep were used to control weeds to determine if grazing by these ungulates attract and support potential prey for the insectivorous Hawaiian hoary bat. The assessment focused on types of flies that are often associated with livestock (muscoid flies, including house flies [Muscidae], blow flies [Calliphoridae], flesh flies [Sarcophagidae], and biting midges [Ceratopogonidae]), and moths that may be impacted by changes in the availability of grass. Insect abundance was found to vary in both space and time across the study area, with numbers of muscoid flies and biting midges increasing in the presence of livestock at some stations. Although these insects appeared to respond to livestock grazing in some instances, we did not find statistically significant responses in bat foraging as measured by echolocation activity between grazed stations and the ungrazed reference station. Thus, we found no evidence that suggested bats are drawn to foraging resources in grazed areas. This result may be influenced by several factors, including the size of Hawaiian hoary bat foraging ranges compared to the scale of study area, the type of ungulate and their dung, and the timing of insect activity. Hawaiian hoary bats use KMR and forage seasonally as evidenced by long-term acoustic studies and their presence in the ungulate grazing areas; however, the relatively small size of the ungulate herd and the area that they graze may not be able to support enough prey to have a significant influence on bat foraging rates.