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Quantifying the dominance of little fire ant (wasmannia auropunctata) and its effect on crops in the Solomon islands
BRB
Available Online

Fasi, John

2009
Introduced most probably intentionally, as a biological control against nut fall bugs (Amblypelta sp) in coconut and cocoa, the Little Fire Ant (Wasmannia auropunctata) has for more than 30 years continued to spread and colonies a number of different environments in the Solomon Islands. To date, no studies have investigated the ecological impact of these ants. The impact of Little Fire Ants was measured on (1) the overall ant fauna within subsistence gardens, (2) the prevalence of additional insect pests in subsistence gardens, and (3) the significant pest Tarophagus sp. of one crop - taro and its natural predator Cyrtohinus fulvous. Ant fauna was surveyed on two study areas in garden sites of four common subsistence crops: potato, cassava, taro and yam; a total of 36 gardens per study area with three trials per garden, using baiting and hand collecting. The existence of insect pests that form a relationship with W. auropunctata was measured in the same gardens by standardized visual searches, plus some identification and collecting from randomly selected crop within the gardens. The impact of W. auropunctata on the significant taro pest Tarophagus sp. and its natural predator Cyrtohinus fulvous was measured in 56 taro gardens with half of the gardens infested with Little Fire Ants. Twenty five taro plants were randomly selected in each taro garden and sampled using standardized visual identification. Sites with W. auropunctata had significantly lower mean abundance of other ant species than gardens free of W. auropunctata. A number of hemipteran insects (most of them pests) were also observed to have developed relationships with W. auropunctata. Although there was no significant difference in the mean population density of C. fulvous per taro plant between taro plants infested and free of W. auropunctata, significantly more Tarophagus were found on taro plants in the presence of W. auropunctata than in the absence of W. auropunctata. Three conclusions are drawn here, (1) the presence of W. auropunctata leads to a reduction in the ant fauna at a site, and is likely to lead to ecological damage to other invertebrates and vertebrates, (2) the presence of W. auropunctata in the subsistence crops may have lead to the development of harmful relationships between hemipteran pests and W. auropunctata, and (3) the presence and dominance of W. auropunctata on subsistence crops may provide an environment that i allows insect pests to thrive. Little Fire Ants therefore pose an economic as well as an ecological risk in subsistence gardens in the Solomon Islands
The catastrophic impact of invasive mammalian predators on birds of the UK overseas territories: a review and synthesis
BRB
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Cuthbert, Richard J.

,

Hilton, Geoff M

2010
The UK has sovereignty over 16 Overseas Territories, which hold some of the world's great seabird colonies and collectively support more endemic and globally threatened bird species than the whole of mainland Europe. Invasive alien mammalian predators have spread throughout most of the Territories, primarily since European expansion in the 16th century. Here we review and synthesize the scale of their impacts, historical and current, actions to reduce and reverse these impacts, and priorities for conservation. Mammalian predators have caused a catastrophic wave of extinctions and reductions in seabird colony size that mark the UKOTs as a major centre of global extinction. Mammal-induced declines of threatened endemics and seabird colonies continue, with four Critically Endangered endemics on Gough Island (Tristan da Cunha), St Helena and Montserrat directly threatened by invasive alien House Mice Mus musculus, Feral Cats Felis catus and rats Rattus spp. Action to reduce these threats and restore islands has been modest in comparison with other developed countries, although some notable successes have occurred and a large number of ambitious eradication and conservation plans are in preparation. Priority islands for cosnervation action against mammalian predators include Gough (which according to one published prioritization scheme is the highest-ranked island in the world for mammal eradication), St Helena and Montserrat, but also on Tristan da Cunha, Pitcairn and the Falkland Island. Technical, financial and political will is required to push forward and fund the eradication of invasive mammalian predators on these islands, which would significantly reduce extinction risk for a number of globally threatened species.