LaPointe Dennis A, Goff M Lee, Atkinson Carter T
USGS Pacific Island Ecosystems Research Center, Kilauea Field Station, Hawai'i National Park, Hawai'i 96718, USA.
J Parasitol. 2010 Apr;96(2):318-24. doi: 10.1645/GE-2290.1.
More than half of the Hawaiian honeycreepers (Drepanidinae) known from historical records are now extinct. Introduced mosquito-borne disease, in particular the avian malaria Plasmodium relictum , has been incriminated as a leading cause of extinction during the 20th century and a major limiting factor in the recovery of remaining species populations. Today, most native Hawaiian bird species reach their highest densities and diversity in high elevation (>1,800 m above sea level) forests. We determined the thermal requirements for sporogonic development of P. relictum in the natural vector, Culex quinquefasciatus , and assessed the current distribution of native bird species in light of this information. Sporogonic development was completed at constant laboratory and mean field temperatures between 30 and 17 C, but development, prevalence, and intensity decreased significantly below 21 C. Using a degree-day (DD) model, we estimated a minimum threshold temperature of 12.97 C and a thermal requirement of 86.2 DD as necessary to complete development. Predicted (adiabatic lapse-rate) and observed summer threshold isotherm (13 C) correspond to the elevation of high forest refuges on the islands of Maui and Hawai'i. Our data support the hypothesis that avian malaria currently restricts the altitudinal distribution of Hawaiian honeycreeper populations and provide an ecological explanation for the absence of disease at high elevation.
根据历史记录可知，超过半数的夏威夷蜜旋木雀（Drepanidinae）现已灭绝。外来的蚊媒疾病，尤其是禽疟原虫（Plasmodium relictum），被认为是20世纪物种灭绝的主要原因以及剩余物种种群恢复的主要限制因素。如今，大多数夏威夷本土鸟类物种在高海拔（海拔>1800米）森林中达到最高密度和多样性。我们确定了疟原虫在自然传播媒介致倦库蚊（Culex quinquefasciatus）中进行孢子生殖发育的热需求，并根据这些信息评估了本土鸟类物种的当前分布。在实验室恒定温度和平均田间温度介于30℃至17℃之间时，孢子生殖发育完成，但在21℃以下时，发育、患病率和强度均显著下降。使用度日（DD）模型，我们估计完成发育所需的最低阈值温度为12.97℃，热需求为86.2度日。预测的（绝热递减率）和观测到的夏季阈值等温线（13℃）与毛伊岛和夏威夷岛上高海拔森林避难所的海拔高度相对应。我们的数据支持以下假设：禽疟目前限制了夏威夷蜜旋木雀种群的海拔分布，并为高海拔地区没有疾病提供了生态学解释。
