Modelling population dynamics and response to management options in the poultry red mite Dermanyssus gallinae (Acari: Dermanyssidae)

The poultry red mite Dermanyssus gallinae is a major pest and widespread ectoparasite of laying hens and other domestic and wild birds. Under optimal conditions, D. gallinae can complete its lifecycle in less than 10 days, leading to rapid proliferation of populations in poultry systems. This paper focuses on developing a theoretical model framework to describe the population dynamics of D. gallinae. This model is then used to test the efficacy and residual effect of different control options for managing D. gallinae. As well as allowing comparison between treatment options, the model also allows comparison of treatment efficacies to different D. gallinae life stages. Three different means for controlling D. gallinae populations were subjected to the model using computer simulations: mechanical cleaning (killing once at a given time all accessible population stages), sanitary clearance (starving the mite population for a given duration, e.g. between flocks) and acaricide treatment (killing a proportion of nymphs and adults during the persistence of the treatment). Simulations showed that mechanical cleaning and sanitary clearance alone could not eradicate the model D. gallinae population, although these methods did delay population establishment. In contrast, the complete eradication of the model D. gallinae population was achieved by several successive acaricide treatments in close succession, even when a relatively low treatment level was used.     

Influence of clay content and acidity of soil on development of the earthworm <Emphasis Type="Italic">Lumbricus rubellus</Emphasis> and its population level consequences

In this paper we report on the influence of clay content and acidity of soil on growth and reproduction of the epigeic earthworm species Lumbricus rubellus (Hoffm.), which is common in most temperate soils and abundant in grasslands. Growth, cocoon production and survival of L. rubellus were tested in 12 Dutch soils which differed in soil properties. A matrix model was used to assess the population-level consequences of changes in growth and reproduction. Soil acidity had a strong negative effect on earthworm survival, and the maturation weight decreased with clay content. Individual weight gain in L. rubellus decreased with both acidity and clay content. The acidity of soils had a larger influence on population growth rate than the clay content. The acidity of the soil also changed the population composition towards younger age classes, whereas in soils rich in clay, the population composition did not change. The average individual weight of L. rubellus in clayey soils, however, was lower compared with that in soils low in clay, a result that agrees with literature data.     

Alcohol diluent provides the optimal formulation for calcium chloride non-surgical sterilization in dogs

Background

Surgical castration is widely used to sterilize male dogs, but has significant impacts on time to perform the operation, recovery of the animals as well as cost, which can limit population control programs. Previous research has shown intratesticular injection of calcium chloride dihydrate (CaCl₂) in saline to be a promising alternative to surgery. However, long-term azoospermia was not maintained at dosages low enough to avoid side effects. In the search for an optimized formulation, the current investigation is the first study on long-term sterilization effects of intratesticular injection of CaCl₂ in either lidocaine solution or alcohol in dogs. CaCl₂ at 20% concentration in lidocaine solution or alcohol was administered via intratesticular injection to groups of 21 dogs each. The treated animals were examined at 2, 6, and 12 months for sperm production, blood levels of testosterone, and side effects; at time zero and 12 months for testicular size and semen volume. The experimentally treated animals were compared to a control group receiving saline injection only.

Results

Testicles of dogs treated with CaCl₂ in either diluent significantly decreased in size. After administration of CaCl₂ in lidocaine solution, sterility was achieved for at least 12 months in 75% of treated dogs. However, optimal long-term contraceptive effectiveness was achieved with CaCl₂ in alcohol, which resulted in azoospermia over the 12-month study period. Testosterone levels significantly decreased following treatment with CaCl₂, and sexual activity disappeared. Although testosterone returned to baseline levels by 12 months for the group treated with CaCl₂ in lidocaine, dogs injected with CaCl₂ in alcohol had a 63.6% drop in testosterone level, which remained at the low end of physiological range throughout the study. No adverse effects were noted.

Conclusions

A single, bilateral intratesticular injection of 20% CaCl₂ in 95% ethanol was a reliable method for induction of sterilization in 18–28 kg male dogs in this study. The approach showed long-term efficacy and reduced sexual behavior. This chemical method of sterilization might provide an effective, efficient alternative to surgical castration that can have positive impacts on dog welfare.     

新城市乡村关系建构与地域圈域化发展选择

对我国城乡关系处理的现状进行了概述,在借鉴日本与韩国地区地域圈域均衡发展的经验的基础上,研究了我国圈域化运作对城乡统筹的影响,即构筑经济循环与物质循环圈域,完善城乡统筹下的地域城市。     

施用硫肥对两种穗型冬小麦品种群体生理、产量和品质的影响

为了研究硫肥对小麦群体生理、产量和品质的影响，以及对不同穗型品种的效应，通过随机区组试验，对豫麦49（多穗型）和兰考906（大穗型）冬小麦品种进行了不同硫肥处理。研究结果表明，适宜的硫肥处理能够增大小麦的叶面积指数（LAI），增加干物质的积累，提高群体光合（CAP）速率，而且对于提高小麦穗粒数、结实率、千粒重、容重、粗蛋白含量、湿面筋含量也有较大的作用。两种穗型小麦品种对硫肥的反应有差异，多穗型的豫麦49施硫后，产量提高幅度较大，而品质反应不明显，大穗型品种兰考906的产量和品质对硫肥的反应却相反，因此硫肥施用应考虑品种间差异。     

基于线粒体 Cytb基因和D-loop区的鸭绿江流域细鳞鱼群体遗传多样性

旨在研究鸭绿江流域（丹东段）细鳞鱼野生群体与养殖群体的遗传多样性,并探究其种质资源情况。基于细鳞鱼线粒体DNA Cytb基因和D-loop区序列,对宽甸（KD）和丹东江域（DD）2个野生细鳞鱼群体和 1个养殖群体的遗传结构与遗传多样性等进行比较研究。结果表明： Cytb基因1 141 bp,A+T含量 53.55%,G+C含量46.45%,D-loop区序列988 bp,A+T含量62.75%,G＋C含量37.25%;基于Cytb和D-loop序列在90个样本中分别检测到42和 56个多态性位点,定义了21和26种单倍型,其中KD、DD和YZ群体 Cytb基因的单倍型数分别为14、10和 7,KD、DD和YZ群体D-loop区单倍型数分别为16、15和10;遗传多样性分析 Cytb基因表现出高单倍型多样性（0.986）和低核苷酸多样性（0.004 66）,而D-loop区表现出高单倍型多样性（0.981）和高水平的核苷酸多样性（0.019 82）,基于 Cytb基因和D-loop区序列KD和DD群体分别具有4个和2个相同单倍型,说明2个细鳞鱼野生群体间的分化程度较小,而养殖群体与野生群体间遗传分化为中度;分子方差分析（AMOVA）发现群体内部的遗传变异（Cytb：73.38%;D-loop：85.91%）占比明显高于群体间的遗传变异（Cytb：26.62%;D-loop：14.09%）,表明鸭绿江流域（丹东段）细鳞鱼群体遗传变异主要来源于群体内,不同地理群体间的遗传变异不大;群体单倍型系统发育树表明,KD、DD和YZ群体间互有交叉,均未表现出明显的地理聚集,3个群体间尚未出现明显的地理谱系结构,结果与遗传多样性研究一致。Tajima’s D和Fu and Li’s中性检验显著偏离中性,推测细鳞鱼KD和DD群体可能经历过群体扩张事件,随后处于相对平衡稳定状态。     

瓮安县黑线姬鼠种群数量变化规律

为探讨黑线姬鼠种群数量的年度、月份、季节变化规律,给其预测预报和防治提供科学依据。对贵州省瓮安县1996²012年稻田、旱地耕作区黑线姬鼠种群组成和种群数量进行统计分析,结果表明:黑线姬鼠为当地农田害鼠优势种,占总鼠数的92.03%。多年平均捕获率为2.70%,随着时间的推移,黑线姬鼠种群数量呈明显的下降趋势。不同年度、不同月份、不同季节之间种群数量存在明显差异。一年中在52012年稻田、旱地耕作区黑线姬鼠种群组成和种群数量进行统计分析,结果表明:黑线姬鼠为当地农田害鼠优势种,占总鼠数的92.03%。多年平均捕获率为2.70%,随着时间的推移,黑线姬鼠种群数量呈明显的下降趋势。不同年度、不同月份、不同季节之间种群数量存在明显差异。一年中在5⁶月和86月和8⁹月出现2个种群数量高峰期,平均捕获率分别为3.16%9月出现2个种群数量高峰期,平均捕获率分别为3.16%³.21%和3.07%3.21%和3.07%³.16%。     

瓜蚜对不同甜瓜品种的取食选择性

选择7个不同甜瓜品种,综合比较了瓜蚜对不同品种室内离体叶片的取食选择性及在室外活体植株上的种群增长动态。结果发现,瓜蚜对IVF437和羊角蜜的叶碟选择性比其他品种低,叶碟选择2 h后羊角蜜和IVF437上的瓜蚜数量为2~3头,选择率为5.54%~7.38%;培养12 h后,羊角蜜和IVF437上的若蚜分别为5.50头和14.00头。且瓜蚜在这2个品种上的种群增长速度也较慢,研究结果为田间甜瓜品种的选择种植及进一步选育抗蚜品种提供了科学基础。     

退化梯度对克氏针茅种群遗传分化的影响

对重度退化、轻度退化和正常样地的克氏针茅种群进行RAPD研究。结果表明,3个种群扩增条带总数、多态位点比率、种群内稀有位点数、遗传多样性和基因多样性均是正常种群>轻度退化种群>重度退化种群。用Shannon指数估算3个种群的遗传多样性,其中72.39%的遗传变异存在于种群内,26.89%存在于种群间。重度退化与轻度退化种群,重度退化与正常种群间的遗传相似系数分别为0.8993和0.8159。在重度退化情况下克氏针茅种群遗传结构发生了一定的遗传分化。     

野生大豆遗传多样性研究Ⅰ4个天然居群等位酶水平的分析

本文采用水平淀粉凝胶电泳技术对分布于北京、山东和大连４个野生大豆天然居群共计１２０个体进行了等位酶水平遗传多样性分析。７个酶系统１３个等位酶位点的检测表明，该地区野生大豆天然居群遗传变异水平较高，多态位点比率Ｐ＝６９．２０，等位基因平均数Ａ＝１．７７，平均期望杂合度Ｈｅ＝０．１３３，居群间有较明显的遗传分化，基因分化系数Ｇｓｔ＝０．３９１，即有３９．１％的遗传变异存在于居群间。本文结果表明该地区遗