Development, survival and fecundity of the urine fly, Scatella (Teichomyza) fusca and predation by the black dumpfly, Hydrotaea aenescens

Development, survival and fecundity for Scatella (Teichomyza) fusca Maquart (Diptera: Ephydridae) were studied at 20 ± 1 °C and 85 ± 10% r.h. Mean (± S.E.) developmental times of eggs, larvae and pupae were 4.0 ± 0.06, 14.9 ± 0.19 and 14.6 ± 0.11 days, respectively, the mean (± S.E.) survival of the original egg cohort to the start of larval, pupal and adult stage being 77.2 ± 3.2%, 54.5 ± 2.6% and 47.9 ± 3.5%, respectively. Females and males displayed approximately straight survivorship curves during adult life, implying constant mortality rates. Mean (± S.E.) adult longevity was 41.6 ± 2.98 days for females and 51.2 ± 3.91 days for males. Assuming a stable age distribution the population consisted of 56% eggs, 31% larvae, 6% pupae and 7% adults. Oviposition peaked when females were 25 days old, and the highest reproductive values (RV_x) (mean ± S.E.) ranged from 129.1 ± 7.57 to 138.5 ± 6.83 for individuals 17–27 days old. A female deposited a mean (± S.E.) of 614.7 ± 35.9 female eggs over a maximum life span of 93 days. The basic reproductive rate (R ₀) (mean ± S.E.) was 173.0 ± 14.2 female offspring per female and the intrinsic rate of natural increase of female individuals (r) (mean ± S.E.) was 0.088 ± 0.001 day^-1. The mean (± S.E.) generation time (T) was 57.8 ± 0.78 days. In cultures with equal numbers of first instar S. fusca larvae and predacious third instar larvae of Hydrotaea aenescens (synonymous Ophyra aenescens) Wiedemann, mean (± S.E.) survival to the adult stage of S. fusca (16.7 ± 8.8%) was significantly lower than in controls with S. fusca alone (58.3 ± 7.4%). The potential significance of predation by H. aenescens on S. fusca in pig farms is discussed.     

桉树枝瘿姬小蜂连续世代种群生命表

桉树枝瘿姬小蜂在广州地区一年发生4-5代,且世代重叠,其越冬期为11月中旬到翌年3月底,越冬虫态为大龄幼虫和蛹.在广州自然条件下,通过人工接种和自然接种相结合的方法,桉树枝瘿姬小蜂在2010年3月至2011年3月间共完成4个世代.利用生命表的方法分析桉树枝瘿姬小蜂连续世代可知,第1代的净增值率R0最大,而第2代的最小;第3代的内禀增长率rm和周限增长率λ最大,其世代平均历期T最小;第4代的rm和λ最小,其T最大.这说明第3代桉树枝瘿姬小蜂的种群增长能力最大,对桉树的危害最强.该代害虫的发生时间为7-9月,因此在防治上要注意该阶段的防控和监测.     

青霉素钠对萼花臂尾轮虫适合度的促进作用及其与藻密度的关系

以萼花臂尾轮虫（Brachionus calyciflorus）为受试动物,在1.0×10⁶（较低）、2.0×10⁶（中等）和4.0×10⁶个细胞/mL （较高）的斜生栅藻（Scenedesmus obliquus）密度下,研究了不同浓度（0、200、400、600、800和1000 μg/L）的青霉素钠对轮虫各生命表统计学参数的影响。结果表明,与各藻密度下的对照组相比,当藻密度为2.0×10⁶个细胞/mL时,200-1000 μg/L的青霉素钠处理组中轮虫的生命期望和世代时间分别延长了40.67%-70.67%和34.04%-50.23%（P<0.05）,净生殖率和内禀增长率分别提高了204.35%-358.70%和36.26%-62.09%（P<0.05）;藻密度的降低或升高均显著降低青霉素钠对轮虫存活、生殖和种群增长的促进幅度。1.0×10⁶ 个细胞/mL的斜生栅藻密度下,400 μg/L的青霉素钠处理组中轮虫的生命期望延长了21%（P<0.05）,200-400μg/L的青霉素钠处理组中轮虫的世代时间延长了23.15%-33.13%（P<0.05）,200-600和1000 μg/L的青霉素钠处理组中轮虫的净生殖率分别升高了40%-81.05%和41.05%（P<0.05）;但4.0×10⁶个细胞/mL的斜生栅藻密度下,各青霉素钠处理组中轮虫的所有生命表统计学参数均与对照组之间无显著性差异（P>0.05）。藻密度对轮虫的生命期望、净生殖率、内禀增长率和后代混交率均具有显著性影响（P<0.01）,青霉素钠浓度对轮虫的世代时间、净生殖率和内禀增长率均具有显著性影响（P<0.05）,藻密度和青霉素钠浓度的交互作用对轮虫的生命期望、净生殖率和内禀增长率也具有显著性影响（P<0.05）。在实验设置的青霉素钠浓度范围内,1.0×10⁶个细胞/mL藻密度下轮虫的生命期望、世代时间和净生殖率与青霉素钠浓度之间均具有显著的剂量-效应关系（P<0.05）;2.0×10⁶个细胞/mL藻密度下,轮虫的生命期望、世代时间和内禀增长率与青霉素钠浓度之间均具有显著的剂量-效应关系（P<0.05）。本研究结果提示,环境相关浓度的青霉素钠不会对萼花臂尾轮虫的存活、生殖和种群增长产生显著性影响。     

甲氰菊酯和阿维菌素对柑橘全爪螨的亚致死效应

通过叶碟饲养的方法, 利用生命表技术,研究了甲氰菊酯和阿维菌素亚致死剂量LC₂₀处理柑橘全爪螨若螨后,对试验种群当代(F₀)和后代(F₁、F₂代)生长发育及繁殖的影响.结果表明: 甲氰菊酯LC₂₀处理若螨后,当代雌成螨产卵量显著增加;F₁、F₂代的产卵前期缩短,后代雌性比例增大,且均与对照差异显著;同时,F₁和F₂代种群内禀增长率(r_m)和周限增长率(λ)增大,世代历期(T)和种群加倍时间(Dt)缩短,且F₂代与对照相比差异显著.用阿维菌素LC₂₀处理若螨后,当代种群雌成螨产卵量显著下降; F₁和F₂代的产卵量也显著下降,但后代雌性比例增大,产卵前期显著缩短;F₁和F₂代的种群r_m和λ增大,T和Dt缩短,且F₂代比F₁代更为明显.总体来看,甲氰菊酯和阿维菌素亚致死浓度LC₂₀对柑橘全爪螨的影响并不完全相同,甲氰菊酯能够促进当代种群的发展,而阿维菌素对当代种群有一定的抑制作用;但两种杀螨剂亚致死浓度处理柑橘全爪螨对后代种群都有一定的促进作用.研究结果对柑橘全爪螨综合防治策略的制定有一定的指导意义.     

An experimental manipulation of life-history trajectories and resistance to oxidative stress

Optimal investment into life-history traits depends on the environmental conditions that organisms are likely to experience during their life. Evolutionary theory tells us that optimal investment in reproduction versus maintenance is likely to shape the pattern of age-associated decline in performance, also known as aging. The currency that is traded against different vital functions is, however, still debated. Here, we took advantage of a phenotypic manipulation of individual quality in early life to explore (1) long-term consequences on life-history trajectories, and (2) the possible physiological mechanism underlying the life-history adjustments. We manipulated phenotypic quality of a cohort of captive zebra finches (Taeniopygia guttata) by assigning breeding pairs to either an enlarged or a reduced brood. Nestlings raised in enlarged broods were in poorer condition than nestlings raised in reduced broods. Interestingly, the effect of environmental conditions experienced during early life extended to the age at first reproduction. Birds from enlarged broods delayed reproduction. Birds that delayed reproduction produced less offspring but lived longer, although neither fecundity nor longevity were directly affected by the experimental brood size. Using the framework of the life-table response experiment modeling, we also explored the effect of early environmental condition on population growth rate and aging. Birds raised in reduced broods tended to have a higher population growth rate, and a steeper decrease of reproductive value with age than birds reared in enlarged broods. Metabolic resources necessary to fight off the damaging effect of reactive oxygen species (ROS) could be the mechanism underlying the observed results, as (1) birds that engaged in a higher number of breeding events had a weaker red blood cell resistance to oxidative stress, (2) red blood cell resistance to oxidative stress predicted short-term mortality (but not longevity), and (3) was related with a parabolic function to age. Overall, these results highlight that early condition can have long-term effects on life-history trajectories by affecting key life-history traits such as age at first reproduction, and suggest that the trade-off between reproduction and self-maintenance might be mediated by the cumulative deleterious effect of ROS.     

Demographic analysis of a declining pika Ochotona collaris population: linking survival to broad-scale climate patterns via spring snowmelt patterns

1. Demographic analysis is essential in order to determine which factors, such as survival, fertility and other life-history characteristics, have the greatest influence on a population's rate of growth (lambda). 2. We used life-table response experiments (LTREs) to assess the relative importance of survival and fertility rates for an alpine lagomorph, the collared pika Ochotona collaris, using 12 years (1995-2006) of census data. The LTRE analysis was repeated for each of three subpopulations within the main study site that were defined by aspect (east, west and south). 3. Across the entire study site, the survival and fertility of adults contributed 35.6 and 43.5%, respectively, to the variance observed in the projected population growth rate, V(lambda), whereas juvenile survival contributed 20.9%. Adult survival and fertility contributed approximately equal amounts for each subpopulation when considered separately, although their rank order varied spatially. 4. Adult survival across the entire site was positively correlated to the Pacific Decadal Oscillation (PDO) with a time lag of 1 year, and was uncorrelated to adult density. The PDO was negatively correlated to the timing of spring snowmelt at our site, implicating the importance of earlier spring conditions and plant phenology on the subsequent winter survival of adults and therefore, population growth. 5. When subpopulations were analysed separately, survivals and fertilities were variously correlated to lagged PDO and adult densities, but the patterns varied spatially. Therefore, the mechanisms underlying V(lambda) can vary substantially over relatively short distances.     

钼对多刺裸腹溞的毒性

运用急性毒性和生命表实验方法,研究了钼对多刺裸腹溞(Moina macrocopa)的急性毒性和生命表统计学参数的影响。结果表明,钼对多刺裸腹溞的48hLC50值为134.46mg·L-1,95%置信区间为107.05～194.53mg·L-1;在2.0～15.0mg·L-1的浓度范围内,钼对多刺裸腹溞的生命期望、世代时间、平均寿命和净生殖率均无显著影响,但对种群内禀增长率有显著影响。空白对照组中,多刺裸腹溞的种群内禀增长率为0.0448±0.0033h-1,显著高于6.4、8.4、11.2和15.0mg·L-1钼浓度下多刺裸腹溞的种群内禀增长率(分别为0.0334±0.0007、0.0327±0.0010、0.0335±0.0003和0.0346±0.0005h-1)。与其他已测试的物种相比,多刺裸腹溞对钼具有较强的敏感性;在所研究的生命表统计学参数中,种群内禀增长率是最敏感的指标。     

Spatial Variation in Lesser Prairie-Chicken Demography: A Sensitivity Analysis of Population Dynamics and Management Alternatives

ABSTRACT The lesser prairie-chicken (Tympanuchus pallidicinctus) is currently considered a candidate for protection under the Endangered Species Act. To identify potential limiting factors for lesser prairie-chicken populations, we developed an age-based matrix model of lesser prairie-chicken population dynamics to compare the relative importance of components of reproduction and survival, and determine if various management alternatives stabilize or increase rates of population change. We based our analyses on an intensive 6-year population study from which demographic rates were estimated for each age class in Kansas. We used deterministic models and elasticity values to identify parameters predicted to have the greatest effect on the rate of population change (λ) at 2 study sites. Last, we used life-stage simulation analysis to simulate various management alternatives. Lambda was <1 for both populations (site 1: λ = 0.54, site 2: λ = 0.74). However, we found differences in sensitivity to nest success and chick survival between populations. The results of the simulated management scenarios complemented the lower-level elasticity analysis and indicated the relative importance of female survival during the breeding season compared with winter. If management practices are only capable of targeting a single demographic rate, changes to either nest success or chick survival had the greatest impact on λ at site 1 and 2, respectively. Management that simultaneously manipulated both nest success and chick survival was predicted to have a greater effect on λ than changes in survival of adult females. In practice, our demographic analyses indicate that effective management should be based on habitat conservation measures to increase components of fecundity.