紫胶虫的生物学研究

紫胶虫Laccifer lacca(Kerr)Targ.在云南自然分布区一年发生两代,各世代有涌散、固定、泌胶、泌蜡和排泄蜜露等活动。由于幼虫在饥饿状态下的存活期较短,迁移能力较差,必须及时实行人工放养和科学管理,才能获得紫胶高产。本文报道了紫胶虫各世代的泌胶量、生殖力和性比,并提出发展紫胶生产的建议。     

云南紫胶虫的地理分布及生态因子的作用

紫胶虫是重要的资源昆虫。本文结合云南西南部、东南部地区云南紫胶虫自然分布区调查结果及相关资料的整理和分析,对生态因子在云南紫胶虫地理分布中的作用进行了归纳。结果表明：云南紫胶虫的地理起源可能是印度洋地区的南亚。云南紫胶虫主要分布于怒江流域及支流、澜沧江流域及支流、红河流域及支流、伊洛瓦底江流域支流河谷两岸半山坡。气候因子中的温湿度组合是决定云南紫胶虫地理分布的主要因子,而寄主植物分布对云南紫胶虫地理分布也有限制作用。云南特有的流域地形、山脉走向及所形成的小气候特点决定了云南紫胶虫在云南的地理分布格局。     

中国紫胶虫的研究

介绍了中国紫胶虫的分类地位、生活史、生物学习性、寄主植物、影响泌胶的因素。提出使紫胶生产高产、稳产的措施。     

紫胶虫最佳生长地的植被条件分析

本文在对紫胶产区进行调查的基础上,分析了云南紫胶虫最佳生长地的植被条件、对其中的四种群落类型从植物种类成分、群落结构和群落生态等方面进行分析。根据丰富的寄主资源和有利于紫胶虫越冬的气候条件指出“暖热性稀树灌草丛”及“河谷季雨林次生林和灌丛”是云南紫胶虫及其主要寄主植物的适生类型。本文在总结紫胶产区的经验基础上,提出了开发利用的意见和改造的措施。     

七种紫胶虫染色体核型分析与亲缘关系探讨

对7种具有重大经济价值的紫胶虫染色体数量、形态及核型进行了分析和比较.7种紫胶虫的染色体形状有棒状、卵圆形、肾形、椭圆形、长圆形以及哑铃形,染色体数目均为2n=18.从核型分析上看,7种紫胶虫的染色体均由中部(或近中部)着丝点染色体与端部着丝点染色体组成,有K=10m 8T, K=8m 10T,K=6m 12T,K=4m 14T四种不同的组成方式.采用Leven et al(1964)、Stebbins(1971)以及Guo et al(1972)核型分类标准对7种紫胶虫进行核型分析,结果显示:信德紫胶虫与紫胶蚧在着丝粒类型、核型对称性和相对长度组成上相一致,因此两者亲缘关系最近;尼泊尔紫胶虫与普萨紫胶虫在核型不对称系数与染色体类型上相近似,两者的关系较为紧密;田紫胶虫与云南紫胶虫的染色体均是由8条中部(或近中部)着丝粒染色体与10条端部着丝粒染色体组成,亲缘关系也较紧密;而中华紫胶虫的核型较为特殊,与其他6种差异较大,亲缘关系较远.研究结果澄清了紫胶生产虫种在分类上的混淆,证实了中国紫胶生产虫种为云南紫胶虫.     

蚂蚁光顾云南紫胶虫对其天敌紫胶黑虫种群的影响

为了弄清蚂蚁光顾云南紫胶虫Kerria yunnanensis Ouet Hong对其天敌紫胶黑虫Holcocera pulverea Meyr种群的影响,于云南紫胶虫成虫期,对有无蚂蚁光顾的胶被抽样,调查胶被上紫胶黑虫的为害率及种群数量变化。结果显示,紫胶黑虫对有无蚂蚁光顾的胶被的为害率均很高,并逐月增加;其中有蚂蚁光顾的胶被紫胶黑虫的为害率略小于无蚂蚁光顾的胶被。蚂蚁光顾能明显减少紫胶黑虫的种群数量(︱t︱=2.764,df=356,P<0.01),其原因可能是蚂蚁光顾能干扰紫胶黑虫的产卵行为、破坏卵、取食卵和幼虫并且这种保护主要发生在云南紫胶虫幼虫期;云南紫胶虫进入成虫期后,由于紫胶黑虫生活于胶被内,并且产卵于胶被的凹陷处或雄虫胶壳内或雌虫肛突孔处,蚂蚁很少与紫胶黑虫相遇,故蚂蚁光顾对紫胶黑虫每月增长量没有显著影响(︱t︱=0.970,df=161,P>0.05)。紫胶黑虫和蚂蚁相遇的行为反应存在显著差异(χ2=4.781,df=1,P<0.05),蚂蚁对紫胶黑虫有捕食作用。蚂蚁与云南紫胶虫之间存在互利关系。蚂蚁取食云南紫胶虫的蜜露,能降低紫胶黑虫的为害率,并减少紫胶黑虫的种群数量,从而保护云南紫胶虫。     

云南紫胶虫八种寄主树次生韧皮部与周皮的解剖

云南紫胶虫８种寄生树的次生韧生皮部轴向系统由筛管、伴胞、韧皮薄壁组织细胞、纤维组成,横向系统为射线。青果榕和久树中分别尚有乳汁和这和分泌组织,滇刺枣与久树中筛板斜到横向,有复筛板,单筛板。蒙自合欢和雨树均具有复筛板,筛板分别为倾斜到横向及倾斜,其余植物的筛板均横向,具单筛板,除蒙自合欢外筛管分子都有Ｐ－蛋白质;除青果榕外筛管分子都具有淀粉。除雨树、宝树、久树外、直径１．５－２．０ｃｍ的小枝条的木拴     

紫胶虫蜜露对地表蚂蚁多样性的影响

2009年12月至2010年5月,采用陷阱法在云南省墨江县雅邑乡调查了紫胶林地表蚂蚁群落多样性,分析了紫胶虫蜜露对地表蚂蚁多样性的影响.结果表明:紫胶虫蜜露资源的有无及变动对地表蚂蚁群落物种组成、多度及多样性均产生影响.在紫胶林样地共采集蚂蚁标本4953头,隶属5亚科23属34种,在对照样地共采集蚂蚁标本2416头,隶属5亚科20属30种;紫胶林地表蚂蚁相对多度、物种丰富度(S)及ACE估计值均高于对照样地,地表蚂蚁常见种和指示种均与对照样地不同,表明放养紫胶虫改变了地表蚂蚁群落结构;紫胶虫成虫期蜜露分泌量高于幼虫期,其地表蚂蚁相对多度、S及ACE估计值也高于幼虫期,且两阶段的蚂蚁常见种和指示种显著不同.     

雄性昆虫性信息素的研究进展

全面概述雄性昆虫性信息素的研究进展。主要从性信息素的释放机制及其作用、已发现的雄性昆虫性信息素及其化学结构进行阐述。通过不同部位释放的雄性昆虫性信息素种类是多样的,但其化学结构的差异又是细微的,雄性昆虫则利用这些差异来引诱雌性昆虫、促进交配和生殖隔离等。最后对雄性昆虫性信息素的研究作了展望。     

Environmental sex reversal,Trojan sex genes,and sex ratio adjustment: conditions and population consequences

The great diversity of sex determination mechanisms in animals and plants ranges from genetic sex determination (GSD, e.g. mammals, birds, and most dioecious plants) to environmental sex determination (ESD, e.g. many reptiles) and includes a mixture of both, for example when an individual’s genetically determined sex is environmentally reversed during ontogeny (ESR, environmental sex reversal, e.g. many fish and amphibia). ESD and ESR can lead to widely varying and unstable population sex ratios. Populations exposed to conditions such as endocrine‐active substances or temperature shifts may decline over time due to skewed sex ratios, a scenario that may become increasingly relevant with greater anthropogenic interference on watercourses. Continuous exposure of populations to factors causing ESR could lead to the extinction of genetic sex factors and may render a population dependent on the environmental factors that induce the sex change. However, ESR also presents opportunities for population management, especially if the Y or W chromosome is not, or not severely, degenerated. This seems to be the case in many amphibians and fish. Population growth or decline in such species can potentially be controlled through the introduction of so‐called Trojan sex genes carriers, individuals that possess sex chromosomes or genes opposite from what their phenotype predicts. Here, we review the conditions for ESR, its prevalence in natural populations, the resulting physiological and reproductive consequences, and how these may become instrumental for population management.     

Intragenomic conflict produces sex ratio dynamics that favor maternal sex ratio distorters

Maternal sex ratio distorters (MSDs) are selfish elements that enhance their transmission by biasing their host's sex allocation in favor of females. While previous models have predicted that the female‐biased populations resulting from sex ratio distortion can benefit from enhanced productivity, these models neglect Fisherian selection for nuclear suppressors, an unrealistic assumption in most systems. We used individual‐based computer simulation modeling to explore the intragenomic conflict between sex ratio distorters and their suppressors and explored the impacts of these dynamics on population‐level competition between species characterized by MSDs and those lacking them. The conflict between distorters and suppressors was capable of producing large cyclical fluctuations in the population sex ratio and reproductive rate. Despite fitness costs associated with the distorters and suppressors, MSD populations often exhibited enhanced productivity and outcompeted non‐MSD populations in single and multiple‐population competition simulations. Notably, the conflict itself is beneficial to the success of populations, as sex ratio oscillations limit the competitive deficits associated with prolonged periods of male rarity. Although intragenomic conflict has been historically viewed as deleterious to populations, our results suggest that distorter–suppressor conflict can provide population‐level advantages, potentially helping to explain the persistence of sex ratio distorters in a range of taxa.     

蜜蜂性别决定与性比调控机理研究

叙述了 4个主要蜜蜂性别决定机理的假说 :即性位点假说、基因平衡假说、蜜蜂性别决定综合假说和性基因数量决定假说。然后就蜜蜂性比由蜂王操纵 ,或是由工蜂操纵进行了论述 ,并对蜜蜂性比调控机理研究提出了一些建议     

粗纹举腹蚁垄断蜜露对紫胶生产的影响

为了解粗纹举腹蚁垄断云南紫胶虫分泌的蜜露对紫胶生产的影响,于2008年10月至2 010年5月,在云南省墨江县雅邑乡调查了粗纹举腹蚁对蜜露的垄断方式,以及粗纹举腹蚁垄 断蜜露对云南紫胶虫的雌雄性比、死亡率、泌胶量和怀卵量的影响.结果表明：在云南紫胶 虫生活史周期内,被粗纹举腹蚁垄断的胶被上,该蚂蚁昼夜不停地取食云南紫胶虫分泌的蜜 露,每10 cm胶被上粗纹举腹蚁的平均数量在（168±23）～（393±100）头,并在 胶被 上建立保护膜,阻止其他动物访问云南紫胶虫.粗纹举腹蚁的垄断显著降低了云南紫胶虫个 体的泌胶量,但是垄断对云南紫胶虫的群体泌胶量没有显著影响;粗纹举腹蚁的垄断 显著降低了云南紫胶虫的死亡率,提高了云南紫胶虫的雌虫比例和个体怀卵量.粗纹举腹 蚁垄断紫胶虫分泌的蜜露有利于紫胶生产.     

Parental control of sex ratio in Gammarus duebeni,an organism with environmental sex determination

Parental sex ratio control was investigated in Gammarus duebeni, an amphipod with an environmentally mediated sex determining system. The effect on the F2 generation sex ratio of the photoperiodic conditions experienced by a) the P generation during and after copulation, b) the F1 generation before and after sex determination, and c) the F2 generation themselves during the period of sex determination, was tested. The photoperiodic conditions the F2 generation experienced during the period of sex determination had a significant effect on their sex ratio (more males were produced under long-day than under short-day conditions), but the photoperiodic conditions experienced by the F1 generation males and females or the P generation on the F1 male's side had no effect on the F2 sex ratio. However, the photoperiodic conditions the P generation on the F1 female's side experienced significantly affected the F2 sex ratio. When these animals experienced long-day conditions the F2 generation became female biased and when they experienced short-day conditions, male biased. It is proposed that the mechanism of control operates through the F1 generation mothers whilst in an embryonic stage of development in the P generation mother's brood pouch. The photoperiodically mediated effects of the embryonic F1 generation mother and the F2 generation on sex determination are additive. A mechanism by which both F1 generation maternal and F2 generation sex ratio control could operate in the field is proposed.     

Sex ratio variance and the maintenance of environmental sex determination

Although variation in population sex ratios is predicted to increase the extinction rate of clades with environmental sex determination (ESD), ESD is still seen in a wide array of natural systems. It is unclear how this common sex-determining system has persisted despite this inherent disadvantage associated with ESD. We use simulation modelling to examine the effect of the sex ratio variance caused by ESD on population colonization and establishment. We find that an accelerating function of establishment success on initial population sex ratio favours a system that produces variance in sex ratios over one that consistently produces even sex ratios. This sex ratio variance causes ESD to be favoured over genetic sex determination, even when the mean global sex ratio under both sex-determining systems is the same. Data from ESD populations suggest that the increase in population establishment can more than offset the increased risk of extinction associated with temporal fluctuations in the sex ratio. These findings demonstrate that selection in natural systems can favour increased variance in a trait, irrespective of the mean trait value. Our results indicate that sex ratio variation may provide an advantage to species with ESD, and may help explain the widespread existence of this sex-determining system.     

Heritable variation of sex ratio in a polychaete worm

Ophryotrocha labronica is a gonochoristic polychaete worm whose sex determining mechanism and sex ratio control are supposed to be polygenic. From a lab population, whose sex ratio (i.e., proportion of males) was 0.5, the estimate of sex ratio heritability by offspring-father regression was 0.54 ± 0.15 and by offspring-mother regression was not significantly different from 0. Estimate of sex ratio repeatability between successive broods of a pair was 0.64 ± 0.33. Since female parents do not contribute in any way to the variability of sex ratio, sex ratio variation seems to be largely a paternal character. On the basis of these estimates we advance the hypothesis that in this species sex is determined by a multilocus genetic system, allowing the combined effects of a female major sex gene (which could give rise to a form of female heterogamety) and masculinizing modifiers. The hypothesis that the male sex has the least canalised sexual differentiation is supported by the observation that some old males developed oocytes.     

Brood sex ratio in the Kentish plover

How and why do the mating opportunities of males and femalesdiffer in natural population of animals? Previously we showedthat females have higher mating opportunities than males inthe Kentish plover Charadrius alexandrinus. Both parents incubatethe eggs, and males provide more brood care than females; thusit is not obvious why the females find new mates sooner thanthe males. In this study we investigated whether the sex-biasedmating opportunities stem from biased offspring sex ratios.We determined the sex of newly hatched, precocial chicks usingCHD gene markers. Among fully sexed broods, 0.461 ± 0.024(SE) of chicks (454 chicks in 158 broods) were male, and thissex ratio was not significantly different from unity. The proportionof males at hatching decreased significantly over the breedingseason, which occurred consistently in all 3 years of the study.Large chicks were more likely to be males than females. Neitherparental age nor body size of male and female parents was relatedto brood sex ratio. We also sexed a number of chicks that werecaught after they left their nest (range of estimated ages 0–17days) and found that the proportion of males increased withbrood age. This relationship remained highly significant whencontrolling statistically for hatching date. As brood size decreaseddue to mortality after the chicks left their nest, these resultssuggest that the mortality of daughters was higher than thatof the sons shortly after hatching. Taken together, our resultsshow that the female-biased mating opportunities in the Kentishplover are not due to biased brood sex ratio at hatching but,at least in part, are due to female-biased chick mortality soonafter hatching.