New Zealand Journal of Marine and Freshwater Research abstracts

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Relationships between mosquito densities in artificial container habitats, land use and temperature in the Kapiti-Horowhenua region, New Zealand

Paul T. Leisnham^1,*
Philip J. Lester²
David P. Slaney^1,3
Philip Weinstein^1,4

¹Ecology and Health Research Centre
Department of Public Health
Wellington School of Medicine
University of Otago
P.O. Box 7343
Wellington South, New Zealand
²School of Biological Sciences
Victoria University of Wellington
P.O. Box 600
Wellington, New Zealand
³Institute of Environmental Science and Research Limited
P.O. Box 50 348
Porirua, New Zealand
⁴School of Population Health
University of Western Australia
Crawley, WA 6009, Australia
*Present address: Department of Biological Sciences, Behavior, Ecology, Evolution and Systematics Section, Illinois State University, Normal, IL 61790–4120, United States. email: pleisnh@ilstu.edu

Abstract Land-use change, including deforestation for agriculture and urbanisation, has coincided with increases in vector-borne diseases worldwide. Land-use change is likely to regulate immature (larvae and pupae) mosquito populations through changes in local temperatures owing to manifold changes to the physical environment. However, we still poorly understand the relationship between land use, water temperature, and immature mosquito density. We conducted a field study in the Kapiti-Horowhenua region, New Zealand, to examine the relationship between land use, water temperature, and immature mosquito population dynamics in aquatic larval habitats. Artificial container habitats were sampled for immature mosquitoes in native forest, pastureland and urbanland, at three replicate locations, from October 2002 to April 2003. The endemic species Culex pervigilans constituted 94.5% of all late-instar larvae collected, the remainder being the exotic Ochlerotatus notoscriptus. On average, significantly higher pupal mosquito densities were recorded from urbanland containers compared with pastureland and native forest containers. A similar trend was observed for total mosquito densities, but did not reach statistical significance. Water temperatures in native forest typically did not show as much variation as those in urbanland and pastureland. Pastureland containers had significantly higher maximum and average daily water temperatures and lower minimum daily water temperatures than native forest containers. Using multiple regression analysis, total mosquito densities were best explained by the quadratic effects of maximum daily temperature and average daily temperature. The results of this study show that pastoral and urban development can increase water temperatures in container habitats, and that land-use change may be responsible for higher immature mosquito densities when habitat water temperatures do not consistently exceed a high threshold.

Keywords Culex pervigilans;disease; land use; mosquitoes; solar radiation; sunlight

New Zealand Journal of Marine and Freshwater Research, 2006, Vol. 40: 285–297
0028–8330/06/4002–0285     © The Royal Society of New Zealand 2006
M05027; Online publication date 10 April 2006. Received 16 May 2005; accepted 20 October 2005

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