警惕鄱阳湖区滨湖农田害鼠暴发成灾

2015年6月、9月和12月在鄱阳湖湖滩草洲和滨湖农田进行了鼠类密度调查,结果表明,农田总捕获率为11.22%,湖滩草洲总捕获率为3.98%,其中水稻田鼠密度非常高,6月、9月、12月合计捕获率分别为6.02%、16.73%和14.94%。尤其在本应该鼠密度较低的冬季,恒湖垦殖场水稻田生境的鼠密度却高达33.54%,说明目前鄱阳湖滨湖农田鼠密度已达较高水平,其中优势鼠种黄毛鼠(Rattus losea)和黑线姬鼠(Apodemus agrarius)的繁殖能力强,在冬季保持了较高的密度,且亚成体以下个体比例较高,如不加控制,有进一步暴发成灾的可能。从鼠种组成看,黑线姬鼠为湖滩生境第一优势种(占比为59.46%),黄毛鼠(32.43%)次之;在滨湖农田黄毛鼠(52.63%)已替代黑线姬鼠(44.41%)成为第一优势种群。由于黄毛鼠体型更大、密度高,其成为第一优势种后的发展动态需密切关注。     

山西隰县社鼠对溴敌隆的敏感性研究

雌雄分开,随机分组,按5个不同食毒期供给浓度为0.000 5%的溴敌隆毒饵,在实验室做单个笼养无选择摄食试验,并用Bliss计算机程序计算不同食毒期与对应死亡率之间的关系。结果表明,社鼠对溴敌隆的敏感性,性别之间差异无统计学意义(Pb>0.05,PLFP50>0.05),故将雌雄数据合并计算,得毒力回归方程y=3.32+3.81x,LFP50,LFP95,LFP99及其95%置信限分别是2.76(2.17～3.51)d,7.47(4.42～12.62)d和11.27(5.79～21.95)d。按世界卫生组织推荐的以致死99%敏感靶标鼠种的食毒期(LFP99)取整天数作为抗药性检验标准,山西隰县地区社鼠摄食浓度为0.000 5%溴敌隆毒饵12 d存活即为抗性鼠。     

Genetic insights into population recovery following experimental perturbation in a fragmented landscape

We investigated the mechanism of population recovery in the Australian bush rat, Rattus fuscipes, following experimental perturbation in a fragmented landscape. Our study involved genetic monitoring over 24 months following the removal of animals from seven sites by intense trapping. A total of 171 bush rats was removed and statistical analysis confirmed a significant knockdown. At one site, local extinction followed the perturbation, while population sizes at 24 months varied from 37% to 90% of the original population size at the remaining sites. The outcomes of genetic analysis at 11 microsatellite loci and mtDNA indicated that population recovery was achieved predominantly by residual animals: recovery populations were genetically more similar to their respective pre-treatment population than near neighbours; assignment tests detected few immigrants; there was no influx of new immigrant alleles and haplotypes. This finding is consistent with emerging evidence for restricted gene flow in bush rats. The local extinction observed at one site indicate that, under severe perturbation restricted dispersal limits opportunities for, and the rate of, population recovery. Thus, while the bush rat appears resilient to substantial population size perturbation, once a critical minimum population size threshold has been reached, this species may be susceptible to local extinction. We concluded that some widespread species currently predicted to be extinction-resilient may, in fact, be at risk if localized extinctions occur and dispersal limitations prevent recolonisation.     

黄胸鼠种群年龄鉴定和种群繁殖研究

对贵州省三都、关岭县1996~2001年1 714只黄胸鼠标本(雌鼠874只,雄鼠840只)以体重指标划分种群年龄,根据体重的频次分配,将黄胸鼠划分为5个年龄组,确定了各年龄组的体重划分标准,幼年组(Ⅰ):小于或等于40.0 g;亚成年组(Ⅱ):40.1~75.0 g;成年Ⅰ组(Ⅲ):75.1~115.0 g;成年Ⅱ组(Ⅳ):115.1~150.0 g;老年组(Ⅴ):150.0 g以上。黄胸鼠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,参与繁殖的群体为成年Ⅰ组、成年Ⅱ组和老年组,平均怀孕率为59.15%,平均胎仔数为6.48只,平均睾丸下降率为96.46%。同时探讨了各年龄组体长、尾长的变化和种群年龄结构。     

应用胴体重指标鉴定贵州省褐家鼠的年龄

为完善贵州省农区主要害鼠种群年龄鉴定划分标准体系建设内容。对2002~2009年贵州省余庆、息烽、三都、关岭、大方5个县捕获的441只褐家鼠(雌鼠201只,雄鼠240只)胴体重统计分析表明,褐家鼠平均胴体重为(69.16±30.45)g,雌、雄鼠之间胴体重差异不显著。根据胴体重的频次分配特征,参照繁殖状况,本研究将褐家鼠划分为5个年龄组,并制定了各年龄组胴体重划分标准:幼年组(Ⅰ)(≤40.0 g),亚成年组(Ⅱ)(40.1~80.0 g),成年Ⅰ组(Ⅲ)(80.1~120.0 g),成年Ⅱ组(Ⅳ)(120.1~160.0 g),老年组(Ⅴ)(160.0 g以上)。研究表明,不同年龄组胴体重、体重、体长、尾长、后足长、耳长之间具有极显著差异,随着种群年龄的增长而不断增加;胴体重与体重、体长、尾长、后足长、耳长之间具有极显著的正相关关系;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51.39%,平均睾丸下降率为93.51%,平均繁殖指数为2.583 9。种群年龄组成具有明显的季节变化特征。     

息烽县褐家鼠形态特征、种群数量动态及预测研究

采用夹夜法调查逐月捕获率,用捕获率表示种群数量,对贵州省息烽县1986～2009年褐家鼠种群数量进行系统监测。结果表明:褐家鼠是当地家栖鼠优势种,占总鼠数的47.68%,为监测和防治的主要对象。年均捕获率为(3.73±0.70)%,最高为(9.26±4.49)%,最低为(1.09±0.30)%。全年种群数量在3月、7月、10月出现3个数量高峰期,平均捕获率分别为(4.74±3.39)%、(4.67±4.33)%、(4.01±3.42)%;1月和12月为数量低谷期,平均捕获率分别为(3.36±1.54)%、(2.67±1.92)%。在不同季节,种群数量变化以夏季(6～8月)最高,平均捕获率为(4.33±3.71)%,冬季(12～2月)最低为(2.75±2.19)%。以此建立以捕获率为单因子指标的预测方程式为:Y1=0.508 2X1+2.459 5,Y2=1.017 1X2+0.849 6,Y3=1.315 8X3-0.263 4,Y4=1.055 7X4+0.866 3,其相关性极显著,可提前1～3个月对褐家鼠种群数量高峰期进行预测。     

Resistance to anticoagulant rodenticides in Germany and future strategies to control Rattus norvegicus

Widespread anticoagulant resistance was discovered in populations of the brown rat (Rattus norvegicus Berk.) in an area of roughly 8000 km² in north-west Germany. Resistance testing was performed by feeding tests and/or by measuring blood clotting response after intraperitoneal injection of a sublethal testing solution. A hierarchical resistance system was found with warfarin resistance at the base followed by bromadiolone/coumatetralyl resistance to difenacoum resistance at the top. Warfarin resistance was spread over the whole area with reduced incidence towards the edges. Difenacoum resistance represented the highest level found so far and was restricted to the inner zone of the resistance area where it occurred with a frequency of 6% of all individuals tested. Breeding experiments with bromadiolone-resistant rats showed that expression of the bromadiolone resistance gene differed in the two sexes, suggesting additional sex-linked modifying effects to the resistance gene. Control strategy within the resistance area with respect to prevention of further selection for resistance is discussed.     

Identification of cytochrome P450 differentiated expression related to developmental stages in bromadiolone resistance in rats (Rattus norvegicus)

Adult, 20-week-old, rats from a Danish bromadiolone-resistant strain of rats (Rattus norvegicus) over-express the cytochrome P450 genes Cyp2e1, Cyp3a2 and Cyp3a3 upon bromadiolone exposure. Furthermore, adult female rats of this strain over-express the Cyp2c13 gene and suppress Cyp2c12, while males over-express the Cyp2a1 gene. The altered gene expression has been suggested to be involved in the bromadiolone resistance by facilitating enhanced anticoagulant metabolism. To investigate the gene expression of these cytochrome P450 genes in rats of different developmental stages we compared expression profiles from 8-, 12- and 20-week-old resistant rats of the Danish strain to profiles of anticoagulant-susceptible rats of same ages. The three age-groups were selected to represent a group of pre-pubertal, pubertal and adult rats. We found expression profiles of the pre-pubertal and pubertal resistant rats to concur with profiles of the adults suggesting that cytochrome P450 enzymes are involved in the Danish bromadiolone resistance regardless of developmental stage. We also investigated the relative importance of the six cytochrome P450s in the different development stages of the resistant rats. The P450-3a2 and -3a3 isoforms were proposed to be of higher importance in adult male resistance than in pre-pubertal resistance. In contrast, the P450-2c13 and -3a2 isoforms were proposed to be more important in sexual immature female resistance, while the P450-2e1 and -3a3 isoforms were suggested to play a more significant role in adult female resistance.