Castro E, Gil A, Piaggio J, Chifflet L, Farias N A, Solari M A, Moon R D
Department of Parasitology, College of Veterinary Medicine, UdelaR, Avda. Lasplaces 1550, C.P. 11600 Montevideo, Uruguay.
Vet Parasitol. 2008 Feb 14;151(2-4):286-99. doi: 10.1016/j.vetpar.2007.10.020. Epub 2007 Nov 9.
Abundance of adult horn flies, Haematobia irritans irritans (L.), was monitored on 25 untreated Hereford cows in Tacuarembó Department, Uruguay, during three consecutive grazing seasons, from October 1999 to May 2002. The population showed a variable pattern of abundance during three years, with peaks in late summer-early fall of each year. Adult flies were continuously present, although in very low numbers in intervening winters. Numbers of flies per cow rarely exceeded a reference level of 200 flies per animal during the grazing season. Degree-day calculations indicated that approximately 12 generations were possible each year. Time series analysis of mean densities among consecutive generations indicated that population growth was governed by simple, direct density-dependence, with additional effects of seasonally varying weather. Response surface regressions confirmed that intergenerational growth was inversely related to mean density, and directly related to temperature. Stochastic simulations with the response surface model suggested that within the range of temperatures observed in our study, horn fly populations on Hereford cattle will tend toward densities of approximately 150 flies per animal in summer, and exceed a nominal level of 200 flies per cow one or more times in about 65 of every 100 grazing seasons.
1999年10月至2002年5月的三个连续放牧季节期间，在乌拉圭塔夸伦博省对25头未经处理的赫里福德奶牛身上的成年角蝇（Haematobia irritans irritans (L.)）数量进行了监测。在三年间，角蝇数量呈现出变化不定的模式，每年夏末秋初出现峰值。成年角蝇一直存在，不过在其间的冬季数量极少。在放牧季节，每头奶牛身上的角蝇数量很少超过每头动物200只的参考水平。度日计算表明每年大约可能有12代。对连续几代之间平均密度的时间序列分析表明，种群增长受简单的直接密度依赖性支配，同时受季节性变化天气的额外影响。响应面回归证实，代际增长与平均密度呈负相关，与温度呈正相关。利用响应面模型进行的随机模拟表明，在我们研究中观察到的温度范围内，赫里福德牛身上的角蝇种群在夏季往往趋于每头动物约150只的密度，并且在每100个放牧季节中约有65个季节会有一次或多次超过每头奶牛200只的标称水平。
