Age-specific metabolic rates and mortality rates in the genus Drosophila

Early theories of aging suggested that organisms with relatively high metabolic rates would live shorter lives. Despite widespread tests of this 'rate of living' theory of aging, there is little empirical evidence to support the idea. A more fine-grained approach that examined age-related changes in metabolic rate over the life span could provide valuable insight into the relationship between metabolic rate and aging. Here we compare age-related metabolic rate (measured as CO2 production per hour) and age-related mortality rate among five species in the genus Drosophila. We find no evidence that longer-lived species have lower metabolic rates. In all five species, there is no clear evidence of an age-related metabolic decline. Metabolic rates are strikingly constant throughout the life course, with the exception of females of D. hydei, in which metabolic rates show an increase over the first third of the life span and then decline. We argue that some physiological traits may have been shaped by such strong selection over evolutionary time that they are relatively resistant to the decline in the force of selection that occurs within the life time of a single individual. We suggest that comparisons of specific traits that do not show signs of aging with those traits that do decline with age could provide insight into the aging process.     

The Floral Biology of Tricyrtis affinis Makino (Liliaceae)

Abstract The floral biology of Tricyrtis affinis was investigated and compared with that of four species of Tricyrtis which had been reported by the author. The flower opens for two days and is protandrous as in T. latifolia, T. flava , and T. ohsumiensis. The primary pollinators of T. affinis were Bombus diversus diversus and Amegilla sp., which were not different from those of the previous species although the shape and the color of the T. affinis flower are somewhat different from the others. The whole perianth of T. affinis absorbs UV light fairly well, and the large purple spotted area near the base absorbs it markedly well. The UV absorption pattern of the T. affinis flower is similar to that of T. latifolia. T. affinis is also self-compatible, like the others, and seeds obtained by self-pollination germinated well. Pollination of T. affinis is characterized by a refined system.     

Bio-inspired synthesis of AgNPs from lichen as potential antibacterial and mosquito larvicidal activity with negligible toxicity on Gambusia affinis

Mosquitoes serve as reservoirs for viruses and other microorganisms, posing a significant health-related issue for both humans as well as livestock. Control of these deadly disease-producing mosquito vectors is of paramount importance. The chemical analysis of Parmotrema reticulatum was examined by GC–MS. Further, lichen-mediated AgNPs were confirmed through UV–vis spectrophotometry, FTIR, TEM-EDX, and XRD. After 24 h post-treatment, the lichen-synthesized AgNPs showed considerable toxicity against distinct Aedes aegypti instars with LC₅₀ values of 44.61 (I instar), 51.27 (II instars), 61.34 (III instars), 72.95 (IV instar), and 89.84 (pupae) μg/mL, respectively. Further, both P. reticulatum extract and AgNPs greatly reduced the survival and reproductive efficiency of A. aegypti adults. Eventually, in conventional laboratory circumstances, the predatory effectiveness of Gambusia affinis against Ae. aegypti II and III instar larvae were 71.35% and 53.40%, respectively. In antibacterial assays, low concentrations of the P. reticulatum synthesized AgNPs inhibited the development of Pseudomonas aeruginosa and Citrobacter freundii. Surface damage, ROS production, and protein leakage are the antibacterial mechanisms of AgNPs. Overall, the lichen-derived AgNPs can be regarded as newer and safer Ae. aegypti control instruments.     

缙云山慈竹种群生物量结构研究

 本文引用Harper的构件结构理论,从两个水平(即群落水平上的种群和个体水平上的种群)上研究了缙云山慈竹种群的生物量结构及其影响因素。 研究结果表明：(1)慈竹无性系种群中各个体生物量在1—5龄级的分配为：14.18%,24.22%,41.91%、12.30%和7.38%,种群现存生物量为156.407t·ha-1;(2)慈竹种群中,生物量在各构件单位的配置为：秆49.46%,枝21.34%,叶8.73%,根茎14.00%,根6.47%;(3)慈竹(合子)种群在200ha中的生物量为31281t。地上地下部分生物量各占种群总量的79.53%和20.47%。     

The effects of sublethal concentrations of five organophosphorus insecticides on temperature tolerance, reflexes, and orientation in Gambusia affinis affinis (Pisces: Poeciliidae)

Gambusia affinis were exposed to the insecticides ABATE®, fenthion, chlorpyrifos, methyl parathion, and malathion for 24 h at concentrations of 1, 5, and 10 ppb and for 48 h at 5 ppb. The thermal tolerance was lowered significantly for male and female G. affinis by the toxicants methyl parathion and chlorpyrifos at 5 and 10 ppb with 24 h exposure. Activity was restricted with fish exposed to methyl parathion and chlorpyrifos at concentrations of 10 ppb for 24 h and at 5 ppb for 48 h.     

红剑鱼、孔雀鱼、食蚊鱼亚慢性毒性试验

目的研究一种快速评价有毒化学品对红剑鱼、孔雀鱼、食蚊鱼慢性毒性的试验方法。方法选择<3d龄的红剑鱼、孔雀鱼、食蚊鱼幼鱼开始暴露,试验药物为国际标准参比毒物Cr6 、Cu2 、Zn2 和Cd2 ,试验温度为25±1℃,每天更换试验液1次,试验持续5d。依据试验鱼的每尾干重和现存量作为观察指标,测定了铬、锌、铜、镉对红剑鱼、孔雀鱼和食蚊鱼的无可观察效应浓度(NOEC)和最低可观察效应浓度(LOEC)。结果铬、锌、铜、镉对红剑鱼和食蚊鱼的NOEC分别是2500、100、10、10μg/L,LOEC分别是5000、200、20、20μg/L。铬、锌、铜、镉对孔雀鱼的NOEC分别是2500、100、10、20μg/L,LOEC分别是5000、200、20、40μg/L;这与7天亚慢性试验结果相接近。结论红剑鱼、孔雀鱼、食蚊鱼,亚慢性毒性试验可从7d缩短为5d。     

生态育苗池中的桡足类与河蟹苗产量的关系

探讨了辽宁盘锦辽河三角洲地区中华绒螯蟹(Eriocheir sinensis)生态育苗池中出现的近亲真宽水蚤(Eurytemor affinis)和细巧华哲水蚤(Sinocalanus tenellus)与中华绒螯蟹幼体的关系.结果表明：近亲真宽水蚤和细巧华哲水蚤都严重地影响Ⅰ期中华绒螯蟹溞状幼体的成活率,其密度越大,Ⅰ期溞状幼体的成活率就越低(P＜0.01); Ⅲ期中华绒螯蟹溞状幼体可捕食桡足类无节幼体,且捕食量随着无节幼体密度增加而变大(P＜0.01);Ⅴ期中华绒螯蟹溞状幼体和大眼幼体容易捕食到近亲真宽水蚤而很难捕食到细巧华哲水蚤;蟹苗池中大眼幼体的产量与育苗初期池塘中桡足类的数量呈负相关关系,且不同桡足类密度下大眼幼体收获量差异极显著(P＜0.01).提出了控制和利用蟹苗池中桡足类的措施.     

Lesser Scaup Breeding Probability and Female Survival on the Yukon Flats,Alaska

ABSTRACT Information on the ecology of waterfowl breeding in the boreal forest is lacking, despite the boreal region's importance to continental waterfowl populations and to duck species that are currently declining, such as lesser scaup (Aythya affinis). We estimated breeding probability and breeding season survival of female lesser scaup on the Yukon Flats National Wildlife Refuge, Alaska, USA, in 2005 and 2006. We captured and marked 93 lesser scaup with radiotransmitters during prelaying and nesting periods. Although all marked lesser scaup females were paired throughout prelaying and incubation periods, we estimated breeding probability over both years as 0.12 (SE = 0.05, n = 67) using telemetry. Proportion of lesser scaup females undergoing rapid follicle growth at capture in 2006 was 0.46 (SE = 0.11, n = 37), based on concentration of yolk precursors in blood plasma. By combining methods based on telemetry, yolk precursors, and postovulatory follicles, we estimated maximum breeding probability as 0.68 (SE = 0.08, n = 37) in 2006. Notably, breeding probability was positively related to female body mass. Survival of female lesser scaup during the nesting and brood-rearing periods was 0.92 (SE = 0.05) in 2005 and 0.86 (SE = 0.08) in 2006. Our results suggest that breeding probability is lower than expected for lesser scaup. In addition, the implicit assumption of continental duck-monitoring programs that all paired females attempt to breed should be reevaluated. Recruitment estimates based on annual breeding-pair surveys may overestimate productivity of scaup pairs in the boreal forest.     

Multi‐scale oviposition site selection in two mosquito species

1. In organisms characterised by complex life cycles, habitat selection often occurs at multiple spatial scales. For instance, female mosquitoes searching for an appropriate aquatic habitat to oviposit their eggs should also consider the characteristics of the terrestrial landscape in which it is embedded. 2. In this study, a field experiment was conducted to test for multi‐scale oviposition site selection in two mosquito species. Artificial pools were placed in two adjacent landscapes, olive plantations and a citrus orchard, mainly differing in their blooming periods and nectar availability. Pools were organised in three pairs: predatory caged fish were present in both pools, in one pool, or in none. 3. Early during the season, most of the egg rafts were laid by Culiseta longiareolata females in pools located within the blooming citrus orchard. When blooming shifted to the olive plantation, C. longiareolata become opportunistic. Culex pipiens females appeared later on during the season, when egg rafts of C. longiareolata were scarce, and they exhibited a higher selectivity to the olive plantation, although its blooming ended. In addition, the selectivity of C. pipiens to fish‐free pools was stronger than that of C. longiareolata. 4. Culex pipiens was more selective, possibly due to its high dispersal ability, which can lower movement cost and enhance the ability to gather environmental information. A trade‐off among gonotrophic cycles, combined with a shorter breeding season and limited recognition ability of the predatory fish may have reduced C. longiareolata selectivity. These differential oviposition patterns can strongly affect the population and community dynamics of both species.