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  • Tags / Keywords rattus sp
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  • Tags / Keywords brodifacoum
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No detection of brodifacoum residues in the marine and terrestrial food web three years after rat eradication at Palmyra Atoll, Central Pacific
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Holmes, N.

,

Howald, G.

,

Shiels, A.

,

Wegmann, A.

2019
Invasive alien species represent one of the greatest threats to native plants and animals on islands. Rats (Rattus spp.) have invaded most of the world’s oceanic islands, causing lasting or irreversible damage to ecosystems and biodiversity. To counter this threat, techniques to eradicate invasive rats from islands have been developed and applied across the globe. Eradication of alien rats from large or complex island ecosystems has only been successful with the use of bait containing a rodenticide. While effective at eradicating rats from islands, rodenticide can persist in the ecosystem longer than the time required to eradicate the target rat population and can potentially harm non-target species. However, the persistence of rodenticides in ecosystems following rat eradication campaigns is poorly understood, though predictions can be made based on the chemical properties of the rodenticide and the environment it is applied in. Brodifacoum, a relatively persistent second-generation anticoagulant, was used to successfully eradicate rats from Palmyra Atoll. With this study, we evaluated the persistence of brodifacoum residues in terrestrial and marine species at Palmyra Atoll (Northern Line Islands) three years after rat eradication. We collected 44 pooled samples containing 121 individuals of the following: mullet (Moolgarda engeli), cockroaches (Periplaneta sp.), geckos (Lepidodactylus lugubris), hermit crabs (Coenobita perlatus), and fiddler crabs (Uca tetragonon). Despite detection of brodifacoum residue in all five of the species sampled in this study 60 days after the application of bait to Palmyra Atoll in 2011, brodifacoum residue was not found in any of the pooled samples collected three years after bait application. Our study demonstrates how brodifacoum residues are unlikely to persist in the marine and terrestrial food web, in a wet tropical environment, three years after rat eradication.
The Ecology of Rodents in the Tonga Islands
BRB
Available Online

Twibell, John

The influence on crop damage of Rattus norvegicus, Rattus rattus, and the native Polynesian rat, Rattus exulans, was studied during the establishment of a rat control program for the Tongan Department of Agriculture in 1969. This was the first long-term study of Tongan rodents. Previous scientific literature on Tongan mammals is very sparse. The Kingdom of Tonga, or Friendly Islands, consists of approximately 150 small islands with a combined area of about 256 square miles at lat 21 0 S. The majority of these islands are composed of raised coral limestone ; however, there is a row of six volcanic islands on Tonga's western border. Tongatapu, the location of the government center, is the largest and most important island. The Ha'apai island group lies 80 miles north of Tongatapu, and 150 miles north is the Vava'u group. Fiji is 420 nautical miles east and Samoa is 480 miles north. The climate is tropical and is influenced seasonally by trade winds. Since Captain Cook's first visit in 1773, Western civilization has brought trade, missionaries, and perhaps rats to Tonga. With this shipping came numerous introduced plants and animals. The arrival dates for the common rat, Rattus norvegicus, and the "European" roof rat, Rattus rattus, are not known, but are believed to be more recent, probably since the increase of regular shipping trade and the construction of wharves. Presently rodents account for approximately 20 percent of the agricultural losses and $50,000 worth of economic loss each year (Twibell, unpublished). This is a conservative estimate based on damage counts and observation. In some areas rats destroy or damage up to 50 percent of the coconuts, which represent the main economic crop in Tonga. THE INFLUENCE on crop damage of Rattus norvegicus, Rattus rattus, and the native Polynesian rat, Rattus exulans, was studied during the establishment of a rat control program for the Tongan Department of Agriculture in 1969. This was the first long-term study of Tongan rodents. Previous scientific literature on Tongan mammals is very sparse. The Kingdom of Tonga, or Friendly Islands, consists of approximately 150 small islands with a combined area of about 256 square miles at lat 21 0 S. The majority of these islands are composed of raised coral limestone ; however, there is a row of six volcanic islands on Tonga's western border. Tongatapu, the location of the government center, is the largest and most important island. The Ha'apai island group lies 80 miles north of Tongatapu, and 150 miles north is the Vava'u group. Fiji is 420 nautical miles east and Samoa is 480 miles north. The climate is tropical and is influenced seasonally by trade winds. Since Captain Cook's first visit in 1773, Western civilization has brought trade, missionaries, and perhaps rats to Tonga. With this shipping came numerous introduced plants and animals. The arrival dates for the common rat, Rattus norvegicus, and the "European" roof rat, Rattus rattus, are not known, but are believed to be more recent, probably since the increase of regular shipping trade and the construction of wharves. Presently rodents account for approximately 20 percent of the agricultural losses and $50,000 worth of economic loss each year (Twibell, unpublished). This is a conservative estimate based on damage counts and observation. In some areas rats destroy or damage up to 50 percent of the coconuts, which represent the main economic crop in Tonga.