Bethany L. Woodworth, et al., "Host population persistence in the face of introduced vector-borne diseases: Hawaii amakihi and avian malaria". Proceedings of the National Academy of Sciences (2005).
*Pacific Island Ecosystems Research Center, U. S. Geological Survey, Kilauea Field Station, P.O. Box 44, Hawaii National Park, HI 96718; and Pacific Cooperative Studies Unit, Department of Botany, University of Hawaii at Mnoa, 3190 Maile Way, St. John 410, Honolulu, HI 96822-2279
Communicated by Peter M. Vitousek, Stanford University, Stanford, CA,
December 17, 2004 (received for review June 1, 2004)
The past quarter century has seen an unprecedented increase in the number
of new and emerging infectious diseases throughout the world, with serious
implications for human and wildlife populations. We examined host persistence
in the face of introduced vector-borne diseases in Hawaii, where introduced
avian malaria and introduced vectors have had a negative impact on most
populations of Hawaiian forest birds for nearly a century. We studied birds,
parasites, and vectors in nine study areas from 0 to 1,800 m on Mauna Loa
Volcano, Hawaii from January to October, 2002. Contrary to predictions
of prior work, we found that Hawaii amakihi (Hemignathus virens), a native
species susceptible to malaria, comprised from 24.5% to 51.9% of the avian
community at three low-elevation forests (55–270 m). Amakihi were more
abundant at low elevations than at disease-free high elevations, and were
resident and breeding there. Infection rates were 24–40% by microscopy
and 55–83% by serology, with most infected individuals experiencing low-intensity,
chronic infections. Mosquito trapping and diagnostics provided strong evidence
for year-round local transmission. Moreover, we present evidence that Hawaii
amakihi have increased in low elevation habitats on southeastern Hawaii
Island over the past decade. The recent emergent phenomenon of recovering
amakihi populations at low elevations, despite extremely high prevalence
of avian malaria, suggests that ecological or evolutionary processes acting
on hosts or parasites have allowed this species to recolonize low-elevation
habitats. A better understanding of the mechanisms allowing coexistence
of hosts and parasites may ultimately lead to tools for mitigating disease
impacts on wildlife and human populations.
Hemignathus virens | host–parasite coevolution | Plasmodium relictum
| Culex quinquefasciatus
Abbreviations: ASL, above sea level; BRY, Bryson's Cinder Cone; MAL, Malama Ki Forest Reserve; NAN, Nanawale Forest Reserve; HY, hatch year; VCP, variable-circular plot.
Present address: U.S. Geological Survey Forest and Rangeland Ecosystem Science Center, 3200 Southwest Jefferson Way, Corvallis, OR 97331.
¶ Present address: Minnesota Cooperative Fish and Wildlife Research Unit, University of Minnesota, 200 Hodson Hall, 1980 Folwell Avenue, St. Paul, MN 55108-6124.
|| Present address: 1260 Bay Shore Road, Brussels, WI 54204.
** Present address: Spring Hill Farm, 135 Princeton Avenue, Hopewell, NJ 08525.
Present address: Biology Department, 414 East Clark Street, University of South Dakota, Vermillion, SD 57069.
Present address: P.O. Box 1056, Volcano, HI 96785.
Present address: 1 Elmwood Drive, Rutland, VT 05701.
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© 2005 by The National Academy of Sciences of the USA