余庆县1986～2008年褐家鼠种群动态及繁殖特征分析

通过对贵州省余庆县1986～2008年褐家鼠种群动态和繁殖特征的变化规律进行研究.结果表明,褐家鼠主要分布于住宅区,是余庆县家栖鼠优势种,占总鼠数的85.14%.研究期间住宅区共捕获褐家鼠504只,种群总性比(♀/♂)0.98,平均捕获率1.53%,平均怀孕率20.40%,平均胎仔数7.33只,平均繁殖指数0.74,平均睾丸下降率27.95%.褐家鼠全年均可繁殖,每年在3月、6月、11月出现3个数量高峰期,在2～3月和10～11月出现2个繁殖高峰期.因此,每年3月和10月为最佳防治时期,毒饵站灭鼠技术是目前防治褐家鼠最好的方法之一.本研究同时还比较了国内其他地区褐家鼠种群动态和繁殖特征的变化规律,以期为其种群数量预测预报和防治提供科学依据.     

息烽县褐家鼠种群繁殖特征变动规律

为摸清息烽县褐家鼠种群繁殖特征的变动规律,通过对息烽县1986-2008年23年系统监测资料统计分析,结果表明,共解剖褐家鼠标本2 672只,其中,雌鼠1 442只,雄鼠1 230只,全年均可繁殖,每年3-11月为主要繁殖期,3月-5月、10月出现2个繁殖高峰,12月至翌年1月出现繁殖低谷期.种群性比(♀/♂)为1.17,多年平均怀孕率为(31.17±11.68)%,平均胎仔数(6.59±0.27)只,平均繁殖指数1.01±0.39,雄鼠睾九平均下降率为(79.53±5.73)%.可为种群数量预测预报和防治提供科学依据.     

三都县褐家鼠种群数量动态与繁殖规律

为了摸清褐家鼠种群数量发生动态及繁殖规律,采用每月定时、定点在住宅区调查,收集鼠类标本,分类鉴定,体外测量,记载性别、怀孕率、胎子数、睾丸下降率、繁殖指数等数据.通过对1990-2008年19年的系统监测结果进行分析,结果表明:三都县住宅区害鼠以褐家鼠为优势种,占总鼠数的50.34%;褐家鼠不同季节均有发生,6月为种群数量最高峰,平均捕获率为3.76%;全年均可繁殖,在4月和10月出现2个繁殖高峰期,平均怀孕率为39.47%和28.46%;种群性比(♀/♂)为0.83.多年平均怀孕率为19.45%,平均胎仔数6.38只,多年平均睾丸下降率39.35%;不同年龄组种群繁殖力存在显著差异;每年春季(3月)和秋季(8-9月)是住宅区灭鼠的关键时期.     

Bait aggregation to reduce cost and toxin use in aerial 1080 baiting of small mammal pests in New Zealand

BACKGROUND: The metabolic toxin sodium fluoroacetate (‘compound 1080’) is widely used for controlling introduced mammalian pests in New Zealand. For large-scale operations, 1080 is distributed aerially in bait to kill brushtail possums (Trichosurus vulpecula Kerr) and ship rats (Rattus rattus L.). While usually successful in reducing pest populations by > 80%, widespread distribution of toxic bait is relatively expensive and raises concerns from some members of the public. Here, trials with spatial aggregation of baits in forested habitats were conducted to determine whether this can reduce toxin usage while maintaining operational efficacy. RESULTS: When 1080 baits were aggregated into clusters (by hand sowing) or into strips (by precision aerial deployment), indices of possum relative abundance were reduced by 92–100%, compared with 73–100% reductions using conventional aerial broadcasting, while all methods reduced relative abundance indices of rats by 88% or greater. Radio tracking indicated a kill rate of > 90% against possums, regardless of bait distribution method. CONCLUSIONS: Simply by modifying bait distribution patterns, spatial aggregation can be used to maintain the high encounter rate of pests with 1080 bait that is necessary for operational efficacy, while reducing current toxin usage by up to 80%. Aggregated bait delivery could have relevance for other mammalian pest control scenarios internationally. Copyright © 2012 Society of Chemical Industry     

Resistance tests and field trials with bromadiolone for the control of Norway rats (Rattus norvegicus) on farms in Westphalia, Germany

BACKGROUND: The aim of this study was to determine the incidence and the level of resistance to bromadiolone among rats on farms suspected of being foci of resistance by using the international normalised ratio (INR)‐based blood clotting response (BCR) test. Whether the level of reduced susceptibility constitutes ‘practical resistance’ was subsequently determined in field trials. RESULTS: The 2.5 multiple of the ED₅₀ baseline was used to test for the incidence of resistance, and higher multiples in the range of the suspected resistance factor were used to investigate the degree of resistance. The ED₅₀ values of bromadiolone in resistant rats were confirmed in the range 4.70–7.05 mg kg^?1 for males and 4.62–6.61 mg kg^?1 for females. Variations within these ranges appeared between farms. According to the BCR resistance tests, 50–100% of rats were classified as resistant prior to the field trials; 29–100% of rats survived the treatments. CONCLUSION: BCR tests based on the use of the INR and baselines are suitable for determining the incidence and for assessing the level of resistance in populations of Norway rats. The majority of rats of the Westphalian resistant strain, characterised by the Y139C marker in VKOR, are resistant to bromadiolone under practical control conditions. Copyright © 2011 Society of Chemical Industry     

Effect of dietary fish oil on fatty acid deposition and expression of cholesterol homeostasis controlling genes in the liver and plasma lipid profile: comparison of two animal models

The objective of the present study was to compare hepatic fatty acid deposition, plasma lipid level and expression of cholesterol homeostasis controlling genes in the liver of rats (Wistar Albino; n = 32) and pigs (Large White × Landrace; n = 32) randomly assigned into two groups of 16 animals each and fed 10 weeks the diet with either 2.5% of fish oil (F; source of eicosapentaenoic and docosahexaenoic acid, EPA+DHA) or 2.5% of palm oil (P; high content of saturated fatty acids; control). F‐rats deposited in the liver three times less EPA, but 1.3 times more DHA than F‐pigs (p < 0.05). Dietary fish oil relative to palm oil increased PPARα and SREBP‐2 gene expression much strongly (p < 0.01) in the pig liver in comparison with the rat liver, but expression of Insig‐1 and Hmgcr genes in the liver of the F‐pigs relative to the expression of these genes in the liver of the P‐pigs was substantially lower (p < 0.01 and p < 0.05 respectively) as compared to rats. When plasma lipid concentration in the F‐animals was expressed as a ratio of the plasma concentration in the P‐counterparts, dietary fish oil decreased HDL cholesterol less (p < 0.01), but LDL cholesterol and triacylglycerols more (p < 0.05 and p < 0.001 respectively) in rats than in pigs: more favourable effect of fish oil on rat plasma lipids in comparison with pigs can therefore be concluded. Concentration of total cholesterol and both its fractions in the rat plasma was negatively correlated (p < 0.01) with hepatic DHA, but also with unsaturated myristic and palmitic acid respectively. It has been concluded that regarding the similarity of the plasma lipid levels to humans, porcine model can be considered superior; however, using this model, dietary fish oil at the tested amount (2.5%) was not able to improve plasma lipid markers in comparison with saturated palm oil.     

褐家鼠的年龄鉴定及种群年龄组成

对1986-2008年贵州省余庆、息烽、大方、三都、关岭5个县捕获的3059只褐家鼠(雌鼠1573只,雄鼠1486只)体重统计表明,褐家鼠平均体重为(108.30±49.00)g,雌、雄鼠之间体重差异不显著.根据体重的频次分配特征,参照繁殖状况,将褐家鼠划分为5个年龄组,制定了各年龄组的体重划分标准,幼年组(Ⅰ):体重小于或等于60.0 g;亚成年组(Ⅱ):60.1～110.0 g;成年Ⅰ组(Ⅲ):110.1～160.0 g;成年Ⅱ组(Ⅳ):160.1～210.0g;老年组(Ⅴ):210.0g以上.不同年龄组种群繁殖力存在显著差异,随着种群年龄的增长,种群繁殖力不断增加,参与种群繁殖的主要群体为成年Ⅰ组、成年Ⅱ组和老年组,平均怀孕率为46.60%,平均胎仔数为7.00只,平均睾丸下降率为91.49%.种群年龄组成具有明显的季节变化特征,不同地区之间种群年龄组成变化基本一致.     

黄胸鼠肥满度变化的特征分析

采用K=100 W/L3作为肥满度指标,对贵州省三都县1997~1999年捕获的405只黄胸鼠肥满度进行分析研究,结果表明:黄胸鼠平均肥满度为3.31±0.75,两性间肥满度差异不显著,不同年龄组之间肥满度差异显著。肥满度的季节变化趋势为:夏季最高,其次为春季和冬季,秋季最低。不同月份之间肥满度存在一定差异,不同年度之间差异极显著。