昆虫抗药性种群相对适合度指标的改进

相对适合度(Relative fitness)是衡量害虫抗药性种群生物学变化的重要指标,用于测度昆虫对杀虫剂的适应性,由抗药性种群和敏感种群净增殖率(R0)相除获得。本文在对多种昆虫抗药性种群相对适合度研究实例分析中发现抗药性昆虫除了后代数量发生变化外,发育时间(如世代历期)也可能会发生变化。因此,提出了基于净增殖率-世代历期(T)、内禀增长率(rm)的2个相对适合度指标模型Rf=R0R/TR/ROS/TS、Rf=rmR/rm S。应用该方法对多个研究实例进行计算,基于净增殖率-世代历期的模型获得的相对适合度值与原模型值相比无显著差异,基于内禀增长率的模型计算出的相对适合度值一般高于原模型值;三个指标之间均极显著相关。改进后的适合度指标包含了抗药性种群发育时间、后代数量或者增殖潜力参数,因此,其结果更具科学性。     

害虫抗药性适合度与内分泌调控研究进展

本文就害虫抗药性适合度与内分泌调控研究进展作了概述。害虫抗药性品系与敏感品系之间在形态、生理反应和生物学特性等方面存在差异 ,通常被认为是抗性基因适应性代价的表现 ,并可能由抗性基因引起的抗性害虫体内生理代谢平衡发生变化产生的。目前就抗性代价的形成机制存在 2种假说 :资源限制假说和干扰代谢平衡假说。害虫抗性和敏感品系的生物适合度差异与其体内激素水平及调控能力变化有关。激素对抗药性相关酶系表达调控的可能机制可分为三类 ,即直接调控、间接调控和共同调控     

抗药性叶螨的种群参数和相对适合度

朱砂叶螨对氧化乐果、三氯杀螨醇、双甲脒和哒螨灵产生抗性后（抗药性系数分别为152．83倍、55．59倍、62．61倍和15．67倍）,繁殖力均显著降低,且发育加速。通过组建各品系生命表得知,该螨抗氧化乐果品系、抗三氯杀螨醇品质、抗双甲脒品系和抗哒螨灵品系的相对适合度分别为0．53、0．62、0．59和0．64,均小于1,具有明显的适合度缺陷。抗药性系数和相对适合度呈直线负相关。     

昆虫的抗药性

随着杀虫剂的使用,越来越多的昆虫对杀虫剂产生了抗性。昆虫的抗药性已经对人类产生了严重的影响。从定义、发展简况、遗传起源、机理、检测方法及治理几个方面加以介绍,对昆虫的抗药性进行了简单的探讨。     

基因组学与昆虫抗药性研究

主要综述近年来基因组学技术在昆虫抗药性研究中的应用以及取得的新成果、新进展。基因组学是对生物体整个基因组结构、功能及其进化的研究。遗传连锁作图、定位克隆、数量特性位点作图、微阵列分析及转录沉默等 ,是近年来常用的基因组学研究技术。研究表明 ,应用基因组技术不仅能揭示新的昆虫抗药性机制 ,发现并定位、克隆新的抗药性基因 ,还有助于发现新型的杀虫剂作用靶标 ,改进昆虫抗药性的检 (监 )测技术以及加深人们对昆虫抗药性进化的认识等。     

昆虫对Bt抗性的适合度代价及其与抗性治理策略的关系

由于昆虫对Bt毒素抗性的发展,不利于Bt制剂和Bl转基因作物的长期有效使用.但是昆虫对Bt抗性的产生常伴有适合度代价,这种代价能够延缓或阻碍抗性等位基因的发展.许多研究已经证明,有分属鳞翅目、鞘翅目以及双翅目的昆虫Bt抗性品系存在适合度代价.适合度代价往往会受生态因素的影响.而且,昆虫适合度代价的产生与其抗性机制密切相关.庇护所策略延缓抗性发展的能力不仅与敏感种群与抗性种群能否自由交配有关,还与适合度代价的大小及抗性基因的显隐性等因素有关.适合度代价的研究对探讨抗性发展规律以及完善抗性治理策略是非常重要的.本文从适合度代价与抗性发展、抗性机制和抗性治理的关系等方面的进行综述,为发展Bt抗性治理策略提供参考依据.     

共生菌与昆虫抗药性

越来越多的研究表明,共生菌与昆虫的抗药性存在一定的联系.在不同的虫菌共生体系中,共生菌和昆虫抗药性联系的表现型存在较大的差异.昆虫对抗药性的生理补偿效应会影响共生菌群落组成.反之,共生菌通过提高宿主的适合度,利用自身的解毒作用或通过免疫系统间接调控宿主的解毒能力来影响宿主昆虫的抗药性.多组学和分子生物学技术的发展有助于...     

共生菌与昆虫抗药性

越来越多的研究表明,共生菌与昆虫的抗药性存在一定的联系.在不同的虫菌共生体系中,共生菌和昆虫抗药性联系的表现型存在较大的差异.昆虫对抗药性的生理补偿效应会影响共生菌群落组成.反之,共生菌通过提高宿主的适合度,利用自身的解毒作用或通过免疫系统间接调控宿主的解毒能力来影响宿主昆虫的抗药性.多组学和分子生物学技术的发展有助于对共生菌和昆虫抗药性的联系进行更深入的研究.     

毛红椿天然种群有性繁殖适合度及其繁殖更新

以九连山国家自然保护区毛红椿4个天然种群为研究对象,于2006—2016年调查毛红椿有性繁殖和自然更新的情况,分析其繁殖适合度系数和个体水平适合度.结果表明:九连山毛红椿各地理种群结实单株的初始数量较少(3~9株),经70余年的繁衍发育,现存结实单株的数量仅2~10株,且来源于原始单株或子1~2代.不同种群间有性繁殖差异显著,但结实能力呈逐年下降的趋势;随群落发育成熟,土壤种子库保存与种子萌发的失利,导致能正常生长发育成熟的林木数量近乎为0.毛红椿最佳性成熟年龄为40年,早期优势明显,适合度系数早期快速增长,为2.0~2.8,但急剧减少至0.3~0.5,之后较平稳减速至近乎于0;种群间个体有性繁殖适合度(0~14株·cm2)存在较显著差异,但均较低,甚至低至0;以现有繁殖率计算,有性繁殖与更新的适合度实测值均远低于预估值.总之,受有性繁殖遗传适合度低的影响,不同种群间有性繁殖与更新能力趋同衰退;个体有性繁殖适合度进一步降低且面临更高的投资风险,现有繁殖体系因此失衡并趋于恶化.建议开展繁殖交配、授粉结实及遗传多样性评价研究,同时人为干预林分环境,于结实期清理林地枯落物,在幼苗至幼树生长过渡期适当疏伐.     

谷胱甘肽S-转移酶与昆虫抗药性的关系

谷胱甘肽S -转移酶 (GSTs)是一种对杀虫剂产生代谢抗性的重要酶系 ,参与许多分子的解毒机制 ,并可转运一些重要的亲脂性化合物。GSTs在保护组织以抵御氧化侵害及氧化压力中起重要的作用。GSTs是昆虫及螨类对有机磷类杀虫剂产生抗生的重要因素     

害虫抗药性的显性水平与抗性进化

对杀虫剂的代谢抗性和主要靶标抗性的显性水平作了理论解释,其中包括昆虫对Bt抗性的显性水平的解释。并对抗性显性具有的多变性作了阐述。分析抗性显性水平与抗药性进化的关系,认为在抗性进化早期抗性表现为显性的基因频率上升快于抗性表现为隐性时;但在抗性等位基因频率较高且出现抗性纯合子个体时,抗性表现为隐性的基因频率上升显著快于抗性表现为显性时。最后论述抗性显性在抗性治理中的应用。     

Evolutionary trade-offs of insect resistance to Bacillus thuringiensis crops: fitness cost affecting paternity

Evolution of resistance to insecticides provides a useful model for examining fitness trade-offs associated with adaptation to stress. Here, we examined male reproductive costs in pink bollworm (Pectinophora gossypiella) resistant to an insecticidal protein of Bacillus thuringiensis (Bt) produced by transgenic cotton, using contrasts between two pairs of related susceptible and resistant strains. Without competition for access to females, no costs affecting reproductive success of resistant males were observed. Resistant and susceptible males had similar mating frequency and fertility. Additionally, fecundity of females mated to resistant and susceptible males was comparable. In competition for matings with virgin females, resistant and susceptible males had comparable success in one strain, whereas susceptible males tended to mate more often than resistant males in the other. However, irrespective of strain origin, resistant males that mated first sired significantly less offspring than susceptible males that mated first. The reduced first-male paternity in resistant males may involve reduced sperm precedence caused by mutations in a cadherin gene linked with resistance to Bt cotton.     

昆虫抗药性分子机制研究的新进展

昆虫抗性机制的研究对于抗性监测、治理及新农药的研制具有重要意义。在过去几十年中,人们对与昆虫杀虫剂抗性有关的昆虫行为、生理代谢活动以及作用靶标等进行了广泛的研究。已经证实,昆虫的抗药性与行为改变、生理功能改变、解毒功能增强以及靶标不敏感性有关。近年来,随着分子生物学以及昆虫基因组学的发展,昆虫抗药性的分子机理有了突破性进展,已发现并克隆了一些靶标基因,与抗药性相关的基因突变也得到广泛验证。本文综述了昆虫的抗药性机理在分子生物学上的研究最新进展,重点阐述了与昆虫抗性相关基因的扩增、表达及基因结构的改变等相关内容。     

Effects of temperature on fitness costs in chlorpyrifos‐resistant brown planthopper,Nilaparvata lugens (Hemiptera: Delphacidae)

Insecticide resistance is inevitable if an insecticide is widely used to control insect pests. Fortunately, the resistance‐associated fitness costs often give chances to manage resistances. In most cases, the fitness cost in resistant insects is often evaluated under laboratory conditions for insect development, which limits its practical application in pest control in the field. In a laboratory population R9 with 253‐fold resistance to chlorpyrifos after nine‐generation selection with chlorpyrifos, the relative fitness was only 0.206 under laboratory conditions (25°C, humidity 70%–80% and 16 h light/8 h dark photoperiod), when compared to S9, a susceptible counterpart (resistance ratio = 2.25‐fold) from the same origin as R9 but without any selection with insecticides. Temperatures varied the resistance‐associated fitness costs, with enhanced costs at high temperatures and reduced costs at low temperatures, such as 0.174 at 32°C and 0.527 at 18°C. The copulation rate and fecundity were two key factors for the reduced costs at low temperatures. Another finding was that R9 individuals needed much more time to recover from heat shock than that of S9, but R9 and S9 individuals were similarly sensitive to cold shock. The low fitness cost at low temperatures would increase the overwintering population, which might further increase risks of rapid development and widespread distribution of chlorpyrifos resistance in Nilaparvata lugens.     

昆虫毒理学发展与展望

论文对昆虫毒理学的发展现状以及我国昆虫毒理学工作者今年取得的成绩进行论述,并对昆虫毒理学的发展做了展望。从研究思路、昆虫毒理学家的数量、发表SCI论文数、杀虫药剂的创制以及毒理机制和杀虫药剂抗药性研究等方面与国外进行了比较。     

The in vitro fitness cost of antimicrobial resistance in Escherichia coli varies with the growth conditions

The objective of this study was to investigate the influence of stressful growth conditions on the fitness cost of antimicrobial resistance in Escherichia coli BJ4 caused by chromosomal mutations and plasmid acquisition. The fitness cost of chromosomal streptomycin resistance increased significantly when the bacteria were grown under all stress conditions tested, while the cost in 1/3 Luria–Bertani was not significantly changed in a streptomycin+rifampicin mutant. The increase in the fitness cost depended in a nonregular manner on the strain/stress combination. The fitness cost of plasmid-encoded resistance on R751 did not differ significantly, and was generally less under stressful growth conditions than in rich media. The fitness cost associated with R751 with the multiple drug resistance cassette from Salmonella Typhimurium DT104 increased significantly only under stressful conditions at low pH and at high-salt concentrations. Strains with an impaired rpoS demonstrated a reduced fitness only during growth in a high-salt concentration. In conclusion, it was demonstrated that bacterial fitness cost in association with antimicrobial resistance generally increases under stressful growth conditions. However, the growth potential of bacteria with antimicrobial resistances did not increase in a straightforward manner in these in vitro experiments and is therefore probably even more difficult to predict in vivo .     

The relationship between multiple mating by queens, within-colony genetic variability and fitness in the ant Lasius niger

Multiple mating has been suggested to benefit social insect queens because high genetic variation within colonies might decrease the load imposed by sterile diploid males, enhance resistance to parasites and pathogens, and lead to a more effective division of labour and/or a wider range of tolerable environmental conditions. We tested these hypotheses in the ant Lasius niger with three population samples from Switzerland and Sweden. We found no diploid males in young or mature colonies suggesting a lack of diploid male load. Colonies with multiply-mated queens were not larger nor did they produce more sexuals than colonies with singly-mated queens. We did find a significantly lower frequency of multiple mating among newly mated queens than among the queens heading mature colonies in one population sample (Switzerland 1997). However, this result was not repeated in the other study population, or in the following year in the Swiss population.