Bdelloid Rotifers from Lakes above 1700 m in Western Italian Alps,with Taxonomic Notes on Dissotrocha macrostyla

Benthic and periphytic bdelloid communities from 16 alpine lakes from 1700 to 2850 m above sea level in Sesia Valley (Piedmont region, North‐western Italy), sampled during summer 2001 and 2002, were analyzed. Seventeen species were identified from these species‐poor communities, with 1 to 6 species each. Dissotrocha macrostyla and Philodina citrina were the most common species, present in 10 lakes while 9 species were collected from one lake only. New morphological details from S.E.M. pictures of Dissotrocha macrostyla revealed that Dissotrocha macrostyla tuberculata (Gosse , 1886) is only a seasonal morphotype. Its different appearance is due to the presence of locally distributed microscopic mucous bubbles (diameter 1.41 ± 0.18 μm) on the trunk surface, produced by the rotifer itself under stressful conditions.     

蛭态轮虫及研究动态

蛭态轮虫是国际无脊椎动物学研究领域关注的热点话题之一。通过对国内外文献的调研,本文重点介绍了蛭态轮虫的形态结构和生物学特征;归纳阐述了蛭态轮虫在形态学、生物多样性与动物地理学、孤雌生殖和低湿休眠发生机理、横向基因转移等领域的最新研究进展。已有的蛭态轮虫研究成果不仅对经典遗传学、生物化学和生理学等的传统理论提出了新的挑战,同时在"转基因"生物安全、新药研究和基因治疗方面也具一定的参考意义;国际上对蛭态轮虫新种的报道和区系的研究成果对丰富全球无脊椎动物多样性以及完善动物地理分布模式都有重要的参考价值。基于该类轮虫研究的现状及其在生物学上意义,建议国内应加强蛭态轮虫的研究。     

Growth pattern of four strains of a Bdelloid rotifer species: egg size and numbers

Life-history traits and growth patterns of four strains of Macrotrachela quadricornifera (Rotifera, Bdelloidea) were studied to assess the influence of maternal traits on egg size. There were two small (S, Va) and two large strains (H, G) with similar patterns of life cycle and body growth. They allocated to reproduction similar relative amounts of resources partitioned into eggs of similar relative size. All strains started reproduction while growing and, although their final sizes differed, at maturity had similar large or small sizes but different ages. Their egg sizes were unaffected by the clutch size, but were positively correlated with mother's body size.     

Epiphytic Rotifer Abundance and Diversity in Moss Patches in Bogs and Fens in the Polesie National Park (Eastern Poland)

Moss‐inhabiting rotifers were studied in 2 raised bogs, 2 poor fens (i.e. intermediate between raised bogs and typical fens), 1 typical fen, and 1 base‐rich fen, located in the Polesie National Park (eastern Poland). Moss samples were collected from April till November 2007 in monthly intervals. In total, 42 taxa of Monogononta and 26 of Bdelloidea were found. Analysis of variance (ANOVA) detected highly significant differences between the habitats in conductivity (F = 37.19, P < 0.001), total organic content (F = 9.34, P < 0.001), total P (F = 51.71, P < 0.001), and nitrate N (F = 48.98, P < 0.001). The mean density of rotifers was the highest in a bog dominated by Sphagnum angustifolium Jensen (Durne Bagno), and the lowest in the base‐rich fen (Bubnów). In all the studied habitats, the Bdelloidea were the most abundant, accounting for 56 to 85% of the total rotifer density. Canonical correspondence analysis (CCA), made for selected physicochemical parameters and taxa, confirms strong relationships between abiotic conditions and selected rotifer taxa: Habrotrocha angusticolis, Dicranophorus capucinus, Keratella serrulata, and Lepadella elliptica. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effects of mating patterns on reproductive performance and offspring fitness in Cryptolaemus montrouzieri

We examined the female mating choice of Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) when exposed to a male with which she had mated before vs. a novel male which she never encountered. After first mating, most females chose to remate with the same male and showed a shorter mating latency period to copulation with the familiar male as compared to a new male. Then, we allowed a female to mate once, 5× with the same, or 5× with different males to evaluate how different mating patterns influence the females’ reproductive performance and offspring fitness. Mating 5× with the same male or different males improved female egg production, but had no effect on hatching rate or offspring fitness. Our findings suggest that female C. montrouzieri are able to distinguish between familiar and unfamiliar males and prefer to mate with the former. Further, multiple mating appears to offer material benefits to female C. montrouzieri specifically by increasing fecundity.     

Macroclimatic and maternal effects on the evolution of reproductive traits in lizards

Much of life‐history theory rests on fundamental assumptions about constraints on the acquisition and allocation of energy to growth and reproduction. In general, the allocation of energy to reproduction depends on maternal size, which in turn depends on environmental factors experienced throughout the life of the mother. Here, we used phylogenetic path analyses to evaluate competing hypotheses about the environmental and maternal drivers of reproductive traits in lizards. In doing so, we discovered that precipitation, rather than temperature, has shaped the evolution of the life history. Specifically, environments with greater rainfall have enabled the evolution of larger maternal size. In turn, these larger mothers produce larger clutches of larger offspring. However, annual precipitation has a negative direct effect on offspring size, despite the positive indirect effect mediated by maternal size. Possibly, the evolution of offspring size was driven by the need to conserve water in dry environments, because small organisms are particularly sensitive to water loss. Since we found that body size variation among lizards is related to a combination of climatic factors, mainly precipitation and perhaps primary production, our study challenges previous generalizations (e.g., temperature‐size rule and Bergmann''s rule) and suggests alternative mechanisms underlying the evolution of body size.     

温度对双委夜蛾种群生态学特征的影响

【目的】双委夜蛾Athetis dissimilis(Hampson)是新发现的一种农业害虫,为探索温度对双委夜蛾生长发育和繁殖的影响。【方法】在室内l6,21,26,30,34(±1)℃,RH为70%±5%、光周期为14L︰10D条件下,测定了双委夜蛾各发育阶段的发育历期、存活率及成虫产卵量,组建了双委夜蛾的实验种群生命表。【结果】结果表明,双委夜蛾各虫态的发育历期随温度的升高而缩短;世代发育起点温度(C)为9.88℃,有效积温(K)为906.53日·度;卵的孵化率在不同的温度下无显著差异;幼虫存活率、化蛹率和羽化率则以21~30℃为最高;成虫的产卵量以21~26℃为最高,而在16℃和30℃时显著降低,在34℃下成虫不能交配,30℃成虫交配率仅为46%;生命表分析表明,26℃双委夜蛾的种群趋势指数和内禀增长率取得最大值,分别为98.5和0.1。【结论】21~26℃是最适宜双委夜蛾生长发育和繁殖的温度范围。     

Importance of carbohydrate sources to the reproductive output of the wheat armyworm Pseudaletia sequax

• 1 The importance of nutrients consumed by adults differs among lepidopteran species. Knowledge of adult nutritional requirements is particularly useful when adopting biological control strategies that involve the use of flowering plants to improve the effectiveness of natural enemies. This is because nectar may also serve as a carbohydrate source for the pest.
• 2 We evaluated the effect of different sources and concentrations of carbohydrate consumed by adults on the performance and fitness of the wheat armyworm Pseudaletia sequax Franclemont, which is an important pest of cereal crops.
• 3 The consumption of carbohydrates by the adults significantly increased the length of the oviposition period, fecundity, fertility and longevity of P. sequax. Adult nutrition also affected the daily oviposition pattern of the females.
• 4 The demographic parameters estimated for each diet regime (i.e. intrinsic rate of increase, finite rate of increase and net reproductive rate) were influenced by adult nutrition. These parameters also varied according to the source and concentration of carbohydrates.
• 5 The results obtained in the present study suggest that the use of perennial flowering plants to provide a food source for natural enemies can also favour the pest.

     

Ecological,Dynamic and Taxonomic Problems Due to <Emphasis Type="Italic">Ludwigia</Emphasis> (Onagraceae) in France

We analyzed meta-community structure of bdelloid rotifers colonizing mosses along an 80 meter section of Rio Valnava in NW Italy. Bdelloid rotifers are small animals living associated with a substratum; colonization in bdelloids can be produced by active animals moving along the riverbed, or by passive dormant propagules, moved by wind. To detect which kind of colonization might be stronger at different spatial scales, we designed a spatially nested sampling experiment at three hierarchical levels: (1) single sample, (2) 10 communities inside each pool, (3) complete section of 10 pools. Assessing species richness and species similarity of communities, and coherence and nestedness of bdelloid meta-communities, we found that different forces may drive species composition at different spatial scales: at the largest scale, colonization of propagules may over-ride direct dispersal between pools, while at the scale of the single pool, differential movements of species give a nested structure to the meta-communities. The number of species increased as the level of analysis increased, even though this study was carried out along only a small stream section.     

Hormonal manipulation of offspring number: maternal effort and reproductive costs

We used exogenous gonadotropin hormones to physiologically enlarge litter size in the bank vole (Clethrionomys glareolus). This method allowed the study design to include possible production costs of reproduction and a trade-off between offspring number and body size at birth. Furthermore, progeny rearing and survival and postpartum survival of the females took place in outdoor enclosures to capture salient naturalistic effects that might be present during the fall and early winter. The aim of the study was to assess the effects of the manipulation on the growth and survival of the offspring and on the reproductive effort, survival, and future fecundity of the mothers. Mean offspring body size was smaller in enlarged litters compared to control litters at weaning, but the differences disappeared by the winter. Differences in litter sizes disappeared before weaning age due to higher mortality in enlarged litters. In addition to the effects of the litter size, offspring performance was probably also influenced by the ability of the mother to support the litter. Experimental females had higher reproductive effort at birth, and they also tended to have higher mortality during nursing. Combined effects of high reproductive effort at birth and high investment in nursing the litter entailed costs for the experimental females in terms of decreased probability of producing a second litter and a decreased body mass gain. Thus, enlarged litter size had both survival and fecundity costs for the mothers. Our results suggest that the evolution of litter size and reproductive effort is determined by reproductive costs for the mothers as well as by a trade-off between offspring number and quality.     

Population development of Frankliniella occidentalis and Thrips hawaiiensis in constant and fluctuating temperatures

Temperature fluctuations may influence the behaviour of insects. Frankliniella occidentalis and Thrips hawaiiensis are sympatric pests on flower and vegetable host plants in China. This study evaluated the influence of constant (23.0°C) and fluctuating temperatures (average of 23.0°C) on the population development of these two species. The results showed that both of these pests showed faster development and higher fecundity at a constant temperature than at fluctuating temperatures when fed on Rosa rugosa flowers, and F. occidentalis showed faster development and higher fecundity than T. hawaiiensis under both conditions. Under the constant and fluctuating temperatures, the development times from egg to adult were 9.57 and 10.62 day for F. occidentalis and 10.71 and 11.82 day for T. hawaiiensis, respectively. The total numbers of first instar nymph produced were 103.08 and 86.32 by F. occidentalis, 86.96 and 73.32 by T. hawaiiensis, under the constant and fluctuating temperatures, respectively, and a higher intrinsic rate of natural increase (r_m) (0.173 and 0.160) and R₀ (46.31 and 36.86) were obtained in F. occidentalis compared with T. hawaiiensis (r_m for 0.154 and 0.141 and R₀ for 34.46 and 27.81, respectively). Our results indicate that the constant temperature had a positive effect on the population development of both F. occidentalis and T. hawaiiensis. Furthermore, F. occidentalis showed a stronger adaptability over T. hawaiiensis at both constant and fluctuating temperatures, according to its faster development and higher fecundity. These results may contribute to the better understanding of the biology of different thrip species, especially the interspecific competition between invasive and native thrips under the changing environment. These findings also provide basic data for the thrip pests control by using fluctuating temperatures.     

高温和啶虫脒处理西花蓟马对其F1 代生命表参数的联合作用

【目的】西花蓟马 Frankliniella occidentalis (Pergande) (缨翅目: 蓟马科）是一种危险的入侵害虫,其生长发育受温度影响显著。我们的前期研究表明,高温热激对西花蓟马的杀灭效果并不理想,但高温热激可以改变西花蓟马的药剂敏感性。为了探究高温热激后再进行杀虫剂减量处理能否提高高温对西花蓟马的防治效果,本实验测定了45℃高温热激 2 h后恢复不同时间（8 h 和24 h）啶虫脒对西花蓟马F₁代生命表参数的影响,从控制种群发展的角度探究高温和啶虫脒防治西花蓟马最佳结合方式。【方法】应用特定年龄 龄期及两性生命表的方法,研究45℃高温热激和啶虫脒处理西花蓟马后其F₁代种群的生命表参数。【结果】45℃热激2 h后恢复不同时间用啶虫脒处理西花蓟马亲代,其F₁代卵、1龄幼虫和蛹的平均发育历期均显著长于对照（仅45℃热激2 h）的西花蓟马F₁代（P<0.01）;而且其F₁代雌成虫的寿命和产卵量均显著少于对照（P<0.01）。热激恢复8 h后啶虫脒处理西花蓟马亲代,其F₁代发育历期和雌成虫的寿命虽然与热激恢复24 h的F₁代不存在显著性差异,但是其F₁代的平均产卵前期（adult pre-oviposition period, APOP）和平均总产卵前期（total pre-oviposition period, TPOP）显著长于恢复24 h的F₁代（P<0.01）,单雌平均产卵量显著小于恢复24 h的F₁代（P<0.01）。【结论】相比单一高温防治,高温和杀虫剂综合使用对西花蓟马有更好的防控效果。相比热激后恢复24 h,热激后恢复8 h再进行杀虫剂处理对西花蓟马有更好的防控效果。     

Coenzyme Q10 restores oocyte mitochondrial function and fertility during reproductive aging

Female reproductive capacity declines dramatically in the fourth decade of life as a result of an age‐related decrease in oocyte quality and quantity. The primary causes of reproductive aging and the molecular factors responsible for decreased oocyte quality remain elusive. Here, we show that aging of the female germ line is accompanied by mitochondrial dysfunction associated with decreased oxidative phosphorylation and reduced Adenosine tri‐phosphate (ATP) level. Diminished expression of the enzymes responsible for CoQ production, Pdss2 and Coq6, was observed in oocytes of older females in both mouse and human. The age‐related decline in oocyte quality and quantity could be reversed by the administration of CoQ10. Oocyte‐specific disruption of Pdss2 recapitulated many of the mitochondrial and reproductive phenotypes observed in the old females including reduced ATP production and increased meiotic spindle abnormalities, resulting in infertility. Ovarian reserve in the oocyte‐specific Pdss2‐deficient animals was diminished, leading to premature ovarian failure which could be prevented by maternal dietary administration of CoQ10. We conclude that impaired mitochondrial performance created by suboptimal CoQ10 availability can drive age‐associated oocyte deficits causing infertility.     

Biological parameters of the predatory mite Cheletomimus bakeri (Acari: Cheyletidae) feeding on Tetranychus cinnabarinus (Acari: Tetranychidae)

Developmental periods of egg, larva and nymphal stages and fecundity as well as predation of Cheletomimus bakeri (Acari: Cheyletidae) feeding on Tetranychus cinnabarinus (Acari: Tetranychidae) were evaluated at different temperatures (15, 20, 25, 30 and 35°C) at 65 ± 10% relative humidity and 16 L: 8D in the laboratory. The development periods of C. bakeri from egg through adult decreased significantly when the temperature was increased from 20°C to 35°C. Egg and total development periods of C. bakeri at 20, 25, 30 and 35°C were 13.86, 7.98, 5.07, 4.08 days and 58.66, 41.51, 21.21, 22.92 days, respectively. The highest numbers of total and daily egg production were found at 20°C and 30°C, respectively. Net reproductive rate (R₀ = 13.29), mean generation time (T = 88.30), gross reproductive rate (GRR = 17.46) and doubling time (DT = 23.66) were the highest at 20°C. The intrinsic rate of increase (r_m = 0.0592) and finite capacity for increase (λ = 1.061) for C. bakeri were the highest at 30°C. Predation of C. bakeri increased throughout the range of prey densities. The highest consumption number of C. bakeri feeding on T. cinnabarinus males per day was 4.63, 4.70 and 4.60 when confined to 40, 80 and 160 individuals, respectively. Our data suggest that C. bakeri does not appear to have much promise for the control of spider mites because of the characteristics of the predator such as slow development period, poor searching capacity and low intrinsic rate of increase.     

Variation in fecundity and other reproductive traits in freshwater mussels

1. Life histories of the highly diverse and endangered North American freshwater mussel fauna are poorly known. We investigated reproductive traits of eight riverine mussel species in Alabama and Mississippi, U.S.A.: Amblema plicata, Elliptio arca, Fusconaia cerina, Lampsilis ornata, Obliquaria reflexa, Pleurobema decisum, Quadrula asperata and Q. pustulosa, and compare our results with existing life history information for other species. 2. These eight species had reproductive traits characteristic of large, outcrossing populations: hermaphrodites were rare, we found no evidence of protandry, and sex ratios were even or slightly male‐biased. 3. Age at sexual maturity varied among species, ranging from <1 to 2 years for L. ornata to 3–9 years for Q. asperata. In all species, most mature females participated in reproduction and fertilisation success was high. 5. Fecundity was related positively to both length and age, but length was the best predictor. In six species, fecundity increased exponentially with increasing size; in two species the rate of increase in fecundity declined in larger animals. In four species, fecundity declined in older animals. These latter results indicate weak reproductive senescence; however, in all species, older individuals continued to produce large numbers of offspring. Mean annual fecundity differed widely among species ranging from 9647 to 325 709. Within‐species differences in fecundity were found among rivers and among populations within a river. 6. The wide variation in reproductive traits among species indicates the existence of widely divergent life history strategies in freshwater mussels.     

Survivorship and fecundity of Argulus bengalensis (Crustacea; Branchiura) under laboratory conditions

The Life table features and the fecundity schedule of the fish louse Argulus bengalensis (Branchiura: Argulidae) were estimated under laboratory conditions using Cirrhinus mrigala as the model host. The cohort-based Life table revealed that survival of A. bengalensis declines as a function of age. Life expectancy was observed to be 34?days for a newly emerged adult. The mean number of eggs produced per egg strip was 86 (±8.89 S.E.). The sex ratio 2:1 was biased towards males. The net reproductive rate (R₀) varied between 50 and 487 while the cohort generation time (T_c) ranged between 24 and 26?days. The intrinsic rate of increase (r) was 0.14–0.23, while the finite rate of increase (λ) remained between 1.16 and 1.28. The Life table features and the fecundity schedule of A. bengalensis are comparable with congenerics of temperate regions. Early reproduction (between 21 and 23?days) and an extended postreproductive phase (47?days) of females are characteristic of A. bengalensis and a reflection for survival under uncertain conditions and a parasitic mode of life.     

Age-stage,two-sex life table of European red spider mite,Panonychus ulmi (Koch) (Prostigmata: Tetranychidae) on mulberry varieties

To understand the influence of four mulberry varieties on the development and reproduction of the European red spider mite, Panonychus ulmi (Koch) (Prostigmata: Tetranychidae), age-stage two-sex life tables of P. ulmi on Goshoerami, KNG, Chinese white and Rokokuyaso varieties were constructed under ambient laboratory conditions during summer season of the year with an average temperature of 26.22 ± 2.23 °C, relative humidity of 70 ± 5% and photoperiod of 14:10 h (L: D). Panonychus ulmi developed comparatively better on KNG and Goshoerami varieties than the other two varieties, as indicated by high fecundity (45.05 ± 1.89 and 41.23 ± 1.66 eggs female^?1, respectively) and intrinsic rate of increase (0.165 ± 0.01 and 0.168 ± 0.03 day^?1, respectively). Lowest intrinsic rate of increase (r) was observed on Chinese white and Rokokuyaso (0.055 ± 0.03 and 0.057 ± 0.10 day^?1, respectively). Total development time of immature females was shortest on KNG than on the other varieties. Immature survival was significantly higher on KNG and Goshoerami varieties (76.76 ± 7.59 and 72.96 ± 8.21%, respectively) and was lower on Chinese white and Rokokuyaso (46.76 ± 9.00 and 43.32 ± 8.71%, respectively). Based on all the above parameters, KNG and Goshoerami were found as most suitable varieties for P. ulmi than Chinese white and Rokokuyaso.