Pacific Science, Volume 62, Number 1, 2008

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    Association Affairs
    (Honolulu, University of Hawaii Press, 2008-01)
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    First Record of Fossorial Behavior in Hawaiian Leafroller Moth Larvae, Omiodes continuatalis (Lepidoptera: Crambidae).
    (Honolulu, University of Hawaii Press, 2008-01) King, Cynthia ; Rubinoff, Daniel
    Larvae of the endemic Hawaiian leafroller moth, Omiodes continuatalis (Wallengren), were used in controlled exposure trials on the island of Maui, Hawai‘i, in May–August 2006, to examine effects of introduced parasitoids on native Hawaiian Lepidoptera. During the trials we observed O. continuatalis larvae burrowing up to 14 cm into the soil beneath plants on which they were deployed. This discovery reflects the first record of fossorial behavior not associated with pupation in larvae of Hawaiian Omiodes and suggests how O. continuatalis, a species once listed as extinct by the U.S. Fish and Wildlife Service, may persist despite intense pressure from introduced biological control agents.
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    Subfossil Land Snail Fauna (Mollusca) of Central Chichijima, Ogasawara Islands, with Description of a New Species.
    (Honolulu, University of Hawaii Press, 2008-01) Chiba, Satoshi ; Sasaki, Tetsuro ; Suzuki, Hajime ; Horikoshi, Kazuo
    The fossil record provides useful information to estimate what island communities were like before human colonization. We examined the species composition of the subfossil land snail fauna of dune deposits at the Yatsuse River, central Chichijima, Ogasawara Islands, and compared it with the species recorded in Chichijima since the nineteenth century. The 22 species in the dune deposits included 13 species that are now extinct in Chichijima. Live specimens of 11 of these extinct species were recorded in the early twentieth century, but no living Mandarna pallasiana and Ogasawarana obtusa Chiba et al., n. sp., have ever been recorded. Age of the sediment, estimated by radiocarbon (14C) dating, was 720 years B.P., and it is possible that these two land snail species became extinct as a result of the impact of human colonization of the island, which started in 1830. Specifically, Ogasawarana obtusa, n. sp., became extinct before the start of taxonomic studies of the land snails of Ogasawara. The sample included Hawaiia minuscula, which is generally now considered a cosmopolitan species introduced from North America. This finding suggests that Hawaiia minuscula is not alien in Ogasawara but indigenous.
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    Characteristics of the Psidium cattleianum (Myrtaceae) Seed Bank in Hawaiian Lowland Wet Forests.
    (Honolulu, University of Hawaii Press, 2008-01) Uowolo, Amanda L. ; Denslow, Julie S.
    Psidium cattleianum Sabine (strawberry guava) is one of Hawai‘i’s most disruptive alien plants. Dense stands can suppress growth and establishment of native species, support high populations of crop-damaging fruit flies, and preclude restoration or management of native forests. Our research investigated factors affecting persistence of P. cattleianum seeds in lowland wet forest soils. We collected soil cores from four forested sites immediately after fruit fall and 6.5 months later. We found abundant germination of P. cattleianum seeds immediately after fruit drop. Soil collected under mature P. cattleianum clumps yielded 761 viable seeds/m2. We found no viable seeds 6.5 months after fruit drop. We evaluated seed longevity using seed bags buried below the litter layer that we retrieved after 28, 56, 196, and 365 days. Seeds either germinated or deteriorated rapidly after fruit drop; after 28 days, 22.3% of the buried seeds were viable and there were no viable seeds at 196 days. Predator effects were assessed using trays with a known number of seeds with and without predator exclosures. After 28 days, 37% of the seeds in the open trays were damaged by predators. The lack of a persistent seed bank likely is due to a combination of rapid, high germination rates, postdispersal seed predation, and seed mortality. We suggest that chemical or mechanical control efforts would be most efficient and effective if conducted at least 3 months after the fruiting season, when the vast majority of seeds have either germinated or died.
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    Patterns of Nestedness in Remote Polynesian Ant Faunas (Hymenoptera: Formicidae).
    (Honolulu, University of Hawaii Press, 2008-01) Morrison, Lloyd W.
    The entire ant faunas of remote Polynesian islands consist of introduced species. An important question concerning the assembly of Pacific island ant faunas is whether these species are a random assortment of the available species pool, or whether they exhibit highly ordered occurrence patterns (i.e., nested subsets of species). I evaluated nestedness for the ant faunas of two island groups in remote Polynesia: (1) the Hawaiian Islands, and (2) French Polynesia and the Cook Islands. Wilcoxon two-sample tests were used to analyze nestedness patterns for individual species and islands; the degree of nestedness for species assemblages and archipelagos was determined by combining tail probabilities of individual species and islands. Both island groups revealed highly significant nestedness at the level of the assemblage (a per-species approach) as well as the archipelago (a per-island approach). Considered individually, most species (73–95%) and most islands (89–100%) demonstrated significant nestedness. Instances of nonsignificant nestedness were frequently associated with low statistical power. These results reveal a strong deterministic element in the assemblage of remote Polynesian ant faunas. Dispersal opportunities along with presence of appropriate habitat type are likely the most important mechanisms underlying the observed patterns.