Releases of biological control agents of insect pests on Easter Island (Pacific Ocean)

For half a century, agriculture on Easter Island has been affected by an increasing number of accidentally introduced insect pests. Due to the absence of natural enemies and other factors, these have reached high density levels which claimed for intensive use of pesticides. A project supported by the National Funds for Regional Development (FNDR) was established in 1984 to develop a biological control program against these pest species. Presently, 60 beneficial species have been introduced to control agricultural pests and flies that affect cattle and humans. Some of the natural enemies have established and are reducing pest populations thereby decreasing the requirement for insecticidal treatments. Fly density has also decreased noticeably. This can be attributed to the activity of natural enemies and dung beetles which compete with larval fly for food.     

First sighting of a tropical benthic reef shark species at Rapa Nui: chance dispersal or a sign of things to come?

On 20 December 2017, a mature Triaenodon obesus was observed at Hanga Roa Bay, Rapa Nui (Easter Island) at c.18 m depth. This observation increases both the range of T. obesus in the Pacific Ocean and the number of elasmobranch species at Rapa Nui. In combination with other recent sightings further extending the southern range of this species during the Austral summer, sea surface temperature is suggested as key to southern dispersal.     

Do some deep‐sea,sediment‐dwelling species of harpacticoid copepods have 1000‐km‐scale range sizes?

The range sizes of sediment‐dwelling deep‐sea species are largely unknown. Such knowledge is important because a deep sea composed in large part of species with 100‐km‐scale ranges would be very different from one composed predominantly of species with 1000‐km‐scale ranges. For example, the total species richness would be much greater in the first case than in the second. As a step towards the determination of the distribution of species’ range sizes in the deep sea, we asked whether harpacticoid copepods (Crustacea) on the continental rise in the northeastern Pacific had 1000‐km‐scale range sizes. We chose harpacticoids because they occur widely in deep‐sea sediments and thus are a typical deep‐sea taxon. In addition, they have no pelagic stage in their life history, so they allow a conservative test of hypotheses about species’ range sizes. We used morphology and gene‐sequence data to assign individuals to species. At least 13.3% of the species we studied had 1000‐km‐scale ranges, raising the question of how these species maintain genetic continuity.     

Migration and isolation effects on the Rapanui population (Easter island) through the analysis of STRs on the Y chromosome

Cultural and biological data suggests the Polynesian origin of the Rapanui population, although the presence of foreign genes in the native population, as a result of admixture with Europeans in the last two centuries has also to be considered. In order to estimate the genetic affinities of the present-day inhabitants of Easter Island and the nearby populations, we used seven polymorphisms of the Y chromosome. However we want to estimate the grade of admixture on the genetic structure that was brought from foreigners within the last two centuries upon the more geographically isolated populations in the world. The preliminary results showed the presence of 18 haplotypes analyzed on 30 male samples. The analysis of the allelic frequency showed a distribution typical of the Polynesian populations. Available data in literature, even with some differences probably due to either the founder effect or historical and ecological events that created sudden demographic variations on the island population. The phylogentic analysis of the haplotypes obtained through Network Median Joining showed two different cluster of haplotypes, of which one represents about 64% of the present haplotypes on Easter Island, which are characterized from the presence of the allele DYS19^*16, very frequent in the Pacific populations. The other cluster is characterized from the presence of the allele DYS19^*14, absent within the populations in the Pacific and with reasonable high frequency within the European populations and South American. Most probably the two clusters are the product of several colonizations that Easter Island had endured from the time of the Chilian and European Colonies. It was demonstrated in fact, that the arrival in 1914 of 50 German and English prisoners would have left a considerable genetic impact on the population of Rapanui, which during this period was of small size.     

Zoogeography of Pacific Ocean islands: a comparison of the rotifer faunas of Easter Island and the Galápagos archipelago

During September 1990, an extensive sampling of the freshwaters of Easter Island was conducted. The resulting list of rotifer species, supplemented by taxa present in samples collected during a previous trip to the island, is compared with that of another oceanic island of volcanic origin, namely Santa Cruz, Galápagos archipelago. In spite of less research, Santa Cruz has a richer rotifer fauna which, unlike Easter Island, includes endemic species. Possible causes for the faunal poverty of Easter Island are: large source-to-target distance, small target size, uniformity of the target island's ecosystems and limited age of its aquatic biotopes.     

Taxonomic review of the Pterostichini and Loxandrini fauna of New Caledonia (Coleoptera, Carabidae)

The generic-level taxa included in Pterostichini and Loxandrini from New Caledonia are reviewed and a key to genera and species provided. Two new genera are described, Paniestichus and Abacophrastus, with the following new species: Paniestichus subsolianus, Abacophrastus millei, Abacophrastus chapes, Abacophrastus carnifex, Abacophrastus hobbit, Abacophrastus megalops, Abacophrastus reflexus and Abacophrastus bellorum. Abacoleptus curtus new species, is described. Notonomus irideus and Notonomus savesi are moved to Prosopogmus. Four new species of Prosopogmus are described: Prosopogmus koghisensis, Prosopogmus lescheni, Prosopogmus fortis and Prosopogmus aoupiniensis. Homalosoma griseolum is moved to Sphodrosomus. Cerabilia is newly recorded from New Caledonia and the genus is moved from Platynini to Loxandrini and therefore is the first report of Loxandrini from New Caledonia. An apparent adventive from Australia, Darodilia, is newly reported from New Caledonia.