Christopher M. Jacobsen

Population Densities of the Coquí, Eleutherodactylus coqui (Anura: Leptodactylidae) in Newly Invaded Hawaii and in Native Puerto Rico

Abstract Eleutherodactylus coqui was accidentally introduced to east Hawaii Island in the late 1980s and has since become established as scattered populations across the island. Mark-recapture study plots indicate that population size remains small for the first year after initial colonization. Plots in heavily forested areas where the Coquí has become well-established yield population estimates of frog density three times the estimates reported from native populations in Puerto Rico. Surveys of the Hilo area using sound pressure level meters found many loud chorusing populations producing sound pressure levels up to 73 dB suggesting that this frog will achieve high densities through broad areas of Hawaiian forest and towns. We suggest that the apparent lack of native or exotic predators in Hawaii and abundance of suitable retreat sites contribute to achievement of unusually high population densities of E. coqui in Hawaii compared with Puerto Rico.

Hot water as a potential disinfestation treatment for an invasive anuran amphibian, the coqui frog, Eleutherodactylus coqui Thomas (Leptodactylidae), on potted plants

The Puerto Rican tree frog, or coqui frog, Eleutherodactylus coqui Thomas (Anura: Leptodactylidae), accidentally introduced in Hawai‘i in 1988, has negatively affected Hawai‘is

Bait Insecticides and Hot Water Drenches Against the Little Fire Ant, Wasmannia auropunctata (Hymenoptera: Formicidae), Infesting Containerized Nursery Plants

105 million floriculture industry as it acquired quarantine status in Hawai‘i, California and Guam. An effective, non-phytotoxic quarantine treatment for E. coqui on potted plants is urgently required. Chemicals available against E. coqui in Hawai‘i, citric acid and hydrated lime (calcium hydroxide), can affect plant appearance, are corrosive, and can be hazardous to human health. The potential of hot water, effective against many arthropods, to disinfest potted plants of E. coqui, was examined. In in vitro trials, no eggs hatched after 2 and 5 min at 43 and 45°C, respectively; 100% mortality of adults was achieved by 5 and 1 min at 39 and 45°C, respectively. Most potted plants tested tolerated 45–49°C water for 5-, 10-, or 15-min durations, with a few exceptions where new leaves and flowers were less heat-tolerant. Hot water is an effective disinfestation treatment for E. coqui on most commercially important potted plants.

Hot Water Immersion for Surface Disinfestation of Maconellicoccus hirsutus (Homoptera: Pseudococcidae)

ABSTRACT Broadcasts of hydramethylnon, S-methoprene, and metaflumizone baits, metaflumizone spray, and hot water drenching were evaluated for their efficacy against the little fire ant, Wasmannia auropunctata (Roger), in potted nursery plants. Two applications one month apart of either a bait containing 0.365% hydramethylnon and 0.25% S-methoprene (Extinguish Plus) or a spray containing 24% metaflumizone (BAS 320 I 240 SC) reduced foraging worker numbers by >97% as compared with untreated controls. The persistence of weather-exposed metaflumizone (0.063%) bait was also evaluated: bait applied fresh or after 7 days of weather exposure resulted in >98% ant mortality; bait exposed to weather for 14 d before application still achieved >90% mortality. In vitro submersion of W. auropunctata in 45°C water for 10 min resulted in >99% mortality as compared with 28.9% mortality from submersion in ambient temperature water (26°C) for 12 min. When W. auropunctata -infested potted plants were drenched with hot water (45.6°C) for 11 min, the number of live ants were reduced by 99.3 and 89.3% in rhapis and fishtail palm, respectively, as compared with control plants drenched with ambient temperature water. The presence of a single W. auropunctata worker in a potted plant would fail to meet export requirements; therefore, the chemical baits and sprays and hot water treatment (45.6°C for 11 min) as evaluated in this study would not individually be a sufficient quarantine protocol against little fire ants in containerized nursery plants.