Mosquito surveillance is essential for the early detection of species incursions and preventing vector-borne disease outbreaks. A variety of traps and attractants (lures), including those that generate CO2, are used in mosquito surveillance. In this study, we measured the CO2 production rate and longevity of three yeast-generated CO2 recipes and evaluated the performance of Biogents (BG) Sentinel traps baited with BG-Lure, yeast-generated CO2, or combined BG-Lure and yeast-generated CO2 for mosquito detection. The recipe containing the highest sugar (500 g) produced significantly larger CO2 volumes and sustained release for longer than other recipes. Traps baited with yeast-generated CO2 captured greater numbers of mosquitoes than those baited with BG-Lure alone or with the combined treatment. Although BG Sentinel traps baited with BG-Lure are currently the primary mosquito surveillance tools at Hawai‘i’s ports of entry, our findings suggest that more effective attractants than BG-Lure may be available and warrant consideration for use in Hawai‘i.
In August of 2023, we conducted the first survey of rat lungworm (Angiostrongylus cantonensis) in wild rats (Rattus spp.) from the island of Kaua‘i since 1964. Our objectives were to capture and obtain specimens of wild rats from Kaua‘i, to confirm infection status of A. cantonensis, and to obtain detailed infection-level data where possible. In addition, we intend to standardize survey protocols for measuring infection levels in Hawai‘i, allowing for more appropriate comparisons between locations and over time. A total of fourteen rats (11 R. exulans, 3 R. rattus) were trapped, 50% of which had adult A. cantonensis worms, and 36% exhibited lung granulation. Here we discuss the relevance of these findings and suggest further surveillance is necessary to better understand the status of rat lungworm throughout the Hawaiian Islands.
Anoplolepis gracilipes (yellow crazy ant), among the world's most damaging invasive ants and likely native to Southeast Asia, occurs in ∼90% of countries and territories in the tropical Pacific islands region. Several characteristics contribute to their socioeconomic and environmental impacts, which primarily affect people's well-being, agriculture and biodiversity. Unpredictable, sometimes repeated, population outbreaks are often observed. They use formic acid for defense, and when in large numbers this enables them to overwhelm prey and competitors. Competition is the major population regulator among ants, and high abundance enables yellow crazy ant populations to dominate other ants. Their abundance is compounded by monopolization of carbohydrate resources, often through mutualisms with honeydew-producing insects. Tolerant of diverse habitats, the ants are likely to increase in latitudinal distribution with climate change. The best management option, preventing their arrival, is possible in only a few locations in the region. Where they are already present, the arrival of new populations should be avoided. Biosecurity efforts should also focus on reducing domestic spread among islands and preventing the arrival of new mutualists. Eradication of yellow crazy ants requires toxicants with potential nontarget impacts and often fails or is prohibitively expensive. Long-term monitoring and effective biosecurity are essential to ensure the ant's continued absence after eradication. The recent interest in genomic approaches to invasive ant control shows promise, as does the use of viruses and other microorganisms. However, these tools are far from operational. We outline recommendations to improve the management of yellow crazy ants in the region.
Length-weight relationships (LWR) are valuable for fisheries stock assessments yet are often sparsely available for coral reef fishes. This study describes the LWR for 15 species of coral reef fish spanning seven families from the Northern Line Islands, a geographically remote and historically understudied area of the central Pacific. Specimens were collected across multiple field campaigns from 2006 to 2011, and the LWR were calculated using the linear regression of the log-transformed total length (TL, 0.1 cm precision) and weight (W, 0.01 g precision) data. Many of these species come from popular food fish families and contribute to large proportions of total reef fish biomass. We found that all but one of the Bayesian point estimates fell outside of the 95% confidence interval for our empirically derived LWR, which underscores the importance of studying under-sampled geographies.
The Norwegian explorer and writer Thor Heyerdahl is most famous for his 1947 Kon-Tiki expedition, a journey performed on a balsa raft, drifting from South America to French Polynesia. However, his exploration of the Pacific to answer questions revolving around the colonization of isolated islands began earlier, in December 1936, when he and his wife, Liv, traveled to Fatu Hiva, one of the most remote locations of the Marquesas Islands. During their year-long stay, Thor Heyerdahl and Liv Torp-Heyerdahl collected ichthyological and herpetological material that has since remained without analysis for more than 80 yr at the Natural History Museum in Oslo. Here, we provide the first identifications of the collected material. Ninety-four specimens have been identified to the species level, three to the genus level, and six specimens remain at the family level or above. The collection comprises mostly fishes, with 66 reef fish specimens encompassing at least 14 species and 27 freshwater specimens covering at least 6 species. Ten specimens of reptiles were also collected by Thor Heyerdahl, including four species of both geckos (Gehyra insulensis and G. oceanica) and skinks (Emoia cyanura and Ornithuroscincus noctua). Many specimens are juveniles, making accurate identification challenging. Incorporating molecular data for species identification is a promising direction for future studies. The expedition marked a turning point in Heyerdahl's career, shifting his focus from zoology to anthropology and setting the stage for his later research on human migration and Pacific cultural connections.
