Life Cycle Patterns, Density, and Frequency of Deformities in Chironomus Larvae (Diptera: Chironomidae) over a Contaminated Sediment Gradient

1992 ◽  
Vol 49 (11) ◽  
pp. 2291-2299 ◽  
Author(s):  
Geert van Urk ◽  
Frans C. M. Kerkurm ◽  
Henk Smit
Keyword(s):  
Life Cycle ◽  
Larval Instar ◽  
Contaminated Sites ◽  
River Rhine ◽  
Contaminated Sediment ◽  
Fourth Larval Instar ◽  
Polluted Sites ◽  
Contamination Levels ◽  
Life Cycle Patterns ◽  
Lower Population

Along a gradient of contamination in Lake Vossemeer (where contaminated sediments from the River Rhine are deposited out), Chironomus cf. plumosus larvae occurred at lower population densities and with higher frequencies of deformities as the contamination levels increased. At the least polluted sites, the frequency of larval deformities was elevated only slightly compared with reference levels. At these sites, C. cf. plumosus had a bivoltine life cycle and overwintered in the fourth larval instar stage. At moderately contaminated sites, the percentage of prepupal larvae was significantly lower in spring and the development of pupae delayed by 2 wk. At heavily contaminated sites, larval densities were strongly reduced and no pupae were observed at all. Under such conditions, population density seems to be a suitable additional indicator of toxic stress. The frequency of deformed larvae was higher from November to April than from July to October. Maximum frequencies were observed during emergence of the overwintering generation, suggesting that the period between February and April may be the most suitable period for the assessment of this parameter.

Coelomomyces infection of the adult female mosquito Aedes trivittatus (Coquillett) in Manitoba

1980 ◽  
Vol 58 (7) ◽  
pp. 1215-1219 ◽  
Author(s):  
B. W. Taylor ◽  
J. A. Harlos ◽  
R. A. Brust
Keyword(s):  
Life Cycle ◽  
Larval Instar ◽  
Pupal Stage ◽  
Time Of Death ◽  
Female Mosquito ◽  
Adult Females ◽  
Fourth Larval Instar ◽  
Infected Adult ◽  
Adult Female Mosquito

Adult females of Aedes trivittatus collected near Winnipeg, Manitoba, were found to be infected with a Coelomomyces sp. The level of infection, as expressed by the formation of sporangia within the haemocoel of the adult, was as high as 56% in blood-fed female mosquitoes. No sporangia were found in females or males that were fed only carbohydrates. Mature sporangia were visible through the abdominal wall of the infected adult at time of death. None of the infected females was able to reproduce. Coelomomyces infection was found to be initiated during the fourth larval instar and (or) pupal stage in artificial pools. Two species of copepods were present in the pools; however, the role of these organisms in the life cycle of the Coelomomyces sp. is not known at this time.

scholarly journals Breaking the rule: Five larval instars in the podonomine midge Trichotanypus alaskensis Brundin from Barrow, Alaska

2018 ◽  
Author(s):  
Alec R. Lackmann ◽  
Malcolm G. Butler
Keyword(s):  
Life Cycle ◽  
Larval Instar ◽  
Adult Emergence ◽  
Head Capsule ◽  
The Arctic ◽  
Larval Instars ◽  
Daily Monitoring ◽  
Field Samples ◽  
Standard Life ◽  
Capsule Size

Except for one unconfirmed case, chironomid larvae have been reported to pass through four larval instars between egg and pupal stages. We have observed a fifth larval instar to be a standard life-cycle feature of the podonomine Trichotanypus alaskensis Brundin 1966 in tundra ponds on the Arctic Coastal Plain near Barrow, Alaska. T. alaskensis has a one-year life cycle in these arctic ponds. Adults emerge in June ~2-3 weeks after pond thaw, then mate and oviposit; most newly-hatched larvae reach instar IV by October when pond sediments freeze. Overwintering larvae complete instar IV within a few days of thaw, then molt again to a fifth larval instar. Imaginal discs, normally seen only during instar IV in Chironomidae, develop across both instars IV & V prior to pupation and adult emergence. While monitoring larval development post-thaw in 2014, we noticed freshly-molted T. alaskensis larval exuviae a week or more prior to any pupation by that species. In 2015-16 we reared overwintering instar IV larvae from single pond sources, individually with daily monitoring, through molts to instar V, pupa, and adult. Some overwintering instar II and III larvae were reared as well, but were few in number. During 2016 we also reared T. alaskensis progeny (from eggs) through instar II, thus documenting head capsule size ranges for all five instars in a single pond’s population. Without individual rearings, the fifth larval instar was not readily apparent for two reasons: 1) The molt itself occurs immediately after thaw and is so synchronous it is difficult to discern in daily field samples. 2) The head capsule size increment between instars IV-V is much lower than the ratio predicted by the Brooks-Dyar Rule. Up through instar IV, the Brooks-Dyar ratio for T. alaskensis ranged 1.30-1.61, but during the IV-V molt head capsule dimensions (sexes pooled) increased by a ratio of 1.09 – comparable to the magnitude of sexual dimorphism in head capsule size within each of the final two larval instars. Individual rearings coupled with 2014-2016 field surveys in nine other ponds suggest that five larval instars is an obligatory trait of this species at this location. As this is the first confirmed case of five larval instars in a chironomid, the phylogenetic uniqueness of this trait needs further investigation.

scholarly journals A Review on the Resistance and Accumulation of Heavy Metals by Different Microbial Strains

2022 ◽  
Author(s):  
Madhuri Girdhar ◽  
Zeba Tabassum ◽  
Kopal Singh ◽  
Anand Mohan
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Volcanic Eruptions ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Contaminated Sites ◽  
Bacillus Species ◽  
Polluted Sites ◽  
Pollution Accumulation ◽  
Microbial Strains

Heavy metals accumulated the earth crust and causes extreme pollution. Accumulation of rich concentrations of heavy metals in environments can cause various human diseases which risks health and high ecological issues. Mercury, arsenic, lead, silver, cadmium, chromium, etc. are some heavy metals harmful to organisms at even very low concentration. Heavy metal pollution is increasing day by day due to industrialization, urbanization, mining, volcanic eruptions, weathering of rocks, etc. Different microbial strains have developed very efficient and unique mechanisms for tolerating heavy metals in polluted sites with eco-friendly techniques. Heavy metals are group of metals with density more than 5 g/cm3. Microorganisms are generally present in contaminated sites of heavy metals and they develop new strategies which are metabolism dependent or independent to tackle with the adverse effects of heavy metals. Bacteria, Algae, Fungi, Cyanobacteria uses in bioremediation technique and acts a biosorbent. Removal of heavy metal from contaminated sites using microbial strains is cheaper alternative. Mostly species involved in bioremediation include Enterobacter and Pseudomonas species and some of bacillus species too in bacteria. Aspergillus and Penicillin species used in heavy metal resistance in fungi. Various species of the brown algae and Cyanobacteria shows resistance in algae.

scholarly journals The Efficiency of Terpenes Extracts of Eucalyptus Camaldulensis Seed to control Larval Stage of Callosobruchus maculates (Coleoptera:Bruchidae)

2016 ◽  
Vol 13 (4) ◽  
pp. 625-630
Author(s):  
Baghdad Science Journal
Keyword(s):  
Mortality Rate ◽  
Larval Stage ◽  
Germination Rate ◽  
Larval Instar ◽  
Eucalyptus Camaldulensis ◽  
Adult Emergence ◽  
Control Treatment ◽  
Fourth Larval Instar ◽  
Cowpea Seed

The current study has beenconduced to evaluate the effect of extracted crude terpens at the concentrations of 6,8% of seeds of Eucalyptuscamaldulensison the 4th larval instar oftheCallosobruchusmaculates and the percentage of the cowpea seed germination.The Results showed that the terpens extract of the concentration of 8% increases the mortality rate of the fourth larval instar and it reach to 63.3%, and then decrease of to 26.6,20% at concentration of 6%and forcontrol treatment respectively The percentage of adult emergence reduces to 0% at the concentration of 8% compared with control treatment in which it reach to 66.6%. The extraction atbothconcentrations 6,8% does not affect the germination rate

Working Class Debt in the Late Nineteenth Century United States

1993 ◽  
Vol 18 (2) ◽  
pp. 111-134 ◽  
Author(s):  
Elyce Rotella ◽  
George Alter
Keyword(s):  
Nineteenth Century ◽  
Life Cycle ◽  
Late Nineteenth Century ◽  
Economic Distress ◽  
Economic Strategies ◽  
The Family ◽  
Late Nineteenth ◽  
Nineteenth Century United States ◽  
Life Cycle Patterns ◽  
Near Future

Children's wages played a central role in family economic strategies in the late nineteenth century. The family budgets collected by the U.S. Commissioner of Labor in 1889-1890 show that life-cycle patterns of savings and debt varied by industry depending upon incomes from children. The consumption patterns of families whose expenditures exceeded their incomes do not show signs of economic distress, and most families whose annual budget was in deficit could expect larger contributions from children in the near future. These patterns suggest that families used borrowing and saving to smooth consumption over the life-cycle as the earning capacity of the family changed.

scholarly journals Life cycle patterns of cognitive performance over the long run

2020 ◽  
Vol 117 (44) ◽  
pp. 27255-27261
Author(s):  
Anthony Strittmatter ◽  
Uwe Sunde ◽  
Dainis Zegners
Keyword(s):  
Life Cycle ◽  
Cognitive Performance ◽  
Individual Performance ◽  
Cycle Performance ◽  
Past Century ◽  
The Past ◽  
Long Run ◽  
Age Patterns ◽  
Life Cycle Patterns ◽  
Over Time

Little is known about how the age pattern in individual performance in cognitively demanding tasks changed over the past century. The main difficulty for measuring such life cycle performance patterns and their dynamics over time is related to the construction of a reliable measure that is comparable across individuals and over time and not affected by changes in technology or other environmental factors. This study presents evidence for the dynamics of life cycle patterns of cognitive performance over the past 125 y based on an analysis of data from professional chess tournaments. Individual move-by-move performance in more than 24,000 games is evaluated relative to an objective benchmark that is based on the respective optimal move suggested by a chess engine. This provides a precise and comparable measurement of individual performance for the same individual at different ages over long periods of time, exploiting the advantage of a strictly comparable task and a comparison with an identical performance benchmark. Repeated observations for the same individuals allow disentangling age patterns from idiosyncratic variation and analyzing how age patterns change over time and across birth cohorts. The findings document a hump-shaped performance profile over the life cycle and a long-run shift in the profile toward younger ages that is associated with cohort effects rather than period effects. This shift can be rationalized by greater experience, which is potentially a consequence of changes in education and training facilities related to digitization.

LEARNING AND LIFE CYCLE PATTERNS OF OCCUPATIONAL TRANSITIONS

2018 ◽  
Vol 60 (2) ◽  
pp. 905-937
Author(s):  
Aspen Gorry ◽  
Devon Gorry ◽  
Nicholas Trachter
Keyword(s):  
Life Cycle ◽  
Occupational Transitions ◽  
Life Cycle Patterns
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