Inequalities in size and intensity-dependent growth in a mermithid nematode parasitic in beach hoppers

2002 ◽  
Vol 76 (1) ◽  
pp. 65-70 ◽  
Author(s):  
R. Poulin ◽  
A.D.M. Latham
Keyword(s):  
Population Genetics ◽  
Intraspecific Competition ◽  
Lorenz Curve ◽  
Egg Production ◽  
Host Size ◽  
Helminth Parasites ◽  
Intensity Of Infection ◽  
Body Sizes ◽  
Dependent Growth ◽  
Mermithid Nematode

AbstractInequality in body sizes is a common feature in populations of helminth parasites, with potential consequences for egg production and population genetics. Inequalities in body lengths and the effects of intraspecific competition on worm length were studied in a species of mermithid nematode parasitic in the crustacean Talorchestia quoyana (Amphipoda: Talitridae). The majority of the 753 worms recovered were relatively small, and an analysis using a Lorenz curve and Gini coefficient suggested that there were no marked inequalities in body lengths among the worms. Total worm length in the 356 infected amphipods (i.e. the sum of the lengths of all the worms in a host) increased steadily as a function of the number of worms per amphipod, whereas the length of the longest worm per amphipod peaked in amphipods harbouring intermediate numbers of worms. This last result was not significantly accounted for by the observed increase in host size with increasing intensity of infection, but resulted from a correlation between worm length and host size. As the number of worms per amphipod increased, the relative sizes of the second-, third-, and fourth-longest worms per host increased markedly. This means that relative inequalities in sizes become less pronounced, i.e. subordinate worms get closer in size to the longest worm, as the number of worms per host increases. The main consequence of this phenomenon is that worm sizes in the mermithid population are more homogeneous than they would be if intraspecific competition had stronger effects on worm growth.

The regulation ofOstertagia ostertagipopulations in calves: density-dependent control of fecundity

Parasitology ◽  
1987 ◽  
Vol 95 (2) ◽  
pp. 373-388 ◽  
Author(s):  
G. Smith ◽  
B. T. Grenfell ◽  
R. M. Anderson
Keyword(s):  
Worm Burden ◽  
Egg Production ◽  
Inverse Function ◽  
Single Infection ◽  
Intensity Of Infection ◽  
Density Dependent ◽  
Helminth Infections ◽  
Model Predictions ◽  
Initial Peak ◽  
Infection Experiments

SUMMARYThe decline in faecal egg counts, characteristic of calves which have been experimentally infected withOstertagia ostertagi, is analysed using a mathematical model in which parasite fecundity is assumed to be an inverse function of both the duration and intensity of infection. The model incorporates a description of the frequency distribution of mature parasites between hosts (which is less over-dispersed than is usual for many other helminth infections). The model provides a good overall description of the decline in faecal egg production observed during trickle and single infection experiments. The main discrepancy between a comparison of the model predictions and the results of the most detailed available series of trickle infection experiments occurs at the initial peak of egg production. The magnitude of this difference appears to be related to the worm burden at the peak of egg production. The possible mechanisms underlying density-dependent regulation of the fecundity ofO. ostertagiaare discussed.

scholarly journals Do parasites adopt different strategies in different intermediate hosts? Host size, not host species, influences Coitocaecum parvum (Trematoda) life history strategy, size and egg production

Parasitology ◽  
2012 ◽  
Vol 140 (2) ◽  
pp. 275-283 ◽  
Author(s):  
R. RUIZ DANIELS ◽  
S. BELTRAN ◽  
R. POULIN ◽  
C. LAGRUE
Keyword(s):  
Host Species ◽  
Egg Production ◽  
Life History Strategy ◽  
Host Size ◽  
Life Strategy ◽  
Amphipod Species ◽  
Intermediate Hosts ◽  
Host Interactions ◽  
Resource Limitations ◽  
Coitocaecum Parvum

SUMMARYHost exploitation induces host defence responses and competition between parasites, resulting in individual parasites facing highly variable environments. Alternative life strategies may thus be expressed in context-dependent ways, depending on which host species is used and intra-host competition between parasites. Coitocaecum parvum (Trematode) can use facultative progenesis in amphipod intermediate hosts, Paracalliope fluviatilis, to abbreviate its life cycle in response to such environmental factors. Coitocaecum parvum also uses another amphipod host, Paracorophium excavatum, a species widely different in size and ecology from P. fluviatilis. In this study, parasite infection levels and strategies in the two amphipod species were compared to determine whether the adoption of progenesis by C. parvum varied between these two hosts. Potential differences in size and/or egg production between C. parvum individuals according to amphipod host species were also investigated. Results show that C. parvum life strategy was not influenced by host species. In contrast, host size significantly affected C. parvum strategy, size and egg production. Since intra-host interactions between co-infecting parasites also influenced C. parvum strategy, size and fecundity, it is highly likely that within-host resource limitations affect C. parvum life strategy and overall fitness regardless of host species.

Reproductive performance in a phyletic dwarf, the spider crab Petramithrax pygmaeus (Bell, 1836) (Decapoda: Brachyura: Mithracidae)

2020 ◽  
Vol 40 (3) ◽  
pp. 325-329
Author(s):  
Joshua T Fields ◽  
Hayden K Mullen ◽  
Clayr M Kroenke ◽  
Kyla A Salomon ◽  
Abby J Craft ◽  
...  
Keyword(s):  
Body Size ◽  
Reproductive Performance ◽  
Related Species ◽  
Egg Production ◽  
Marine Invertebrates ◽  
Small Body ◽  
Reproductive Investment ◽  
Spider Crab ◽  
Closely Related Species ◽  
Body Sizes

Abstract The spider crab Petramithrax pygmaeus (Bell, 1836), a phyletic dwarf, was used to test predictions regarding reproductive performance in small marine invertebrates. Considering the disproportional increase in brooding costs and the allometry of egg production with increasing body size, it was expected that this minute-size species would produce large broods compared to closely related species that attain much larger body sizes. Fecundity in P. pygmaeus females carrying early and late eggs varied, respectively, between 17 and 172 eggs crab–1 (mean ± SD = 87.97 ± 48.39) and between 13 and 159 eggs crab–1 (55.04 ± 40.29). Females did not experience brood loss during egg development. Egg volume in females carrying early and late eggs varied, respectively, between 0.13 and 0.40 mm3 (0.22 ± 0.07) and between 0.15 and 0.42 mm3 (0.26 ± 0.06 mm3). Reproductive output (RO) varied between 0.91 and 8.73% (3.81 ± 2.17%) of female dry body weight. The RO of P. pygmaeus was lower than that reported for closely related species with larger body sizes. The slope (b = 0.95 ± 0.15) of the line describing the relationship between brood and parental female dry weight was not statistically significant from unity. Overall, our results disagree with the notion that the allometry of gamete production and increased physiological costs with increased brood size explain the association between brooding and small body size in marine invertebrates. Comparative studies on the reproductive investment of brooding species belonging to monophyletic clades with extensive differences in body size are warranted to further our understanding about disparity in egg production in brooding marine invertebrates.

Rehydration methods to recover cysticercoids of the rat tapeworm Hymenolepis diminuta from dry flour beetle carcasses

2016 ◽  
Vol 91 (4) ◽  
pp. 470-478 ◽  
Author(s):  
H.M.-H. Chin ◽  
L.T. Luong ◽  
A.W. Shostak
Keyword(s):  
Developmental Stages ◽  
Hymenolepis Diminuta ◽  
Helminth Parasites ◽  
Post Mortem ◽  
Intensity Of Infection ◽  
Internal Organs ◽  
Flour Beetle ◽  
Terrestrial Arthropods ◽  
Early Developmental Stages ◽  
Early Developmental

AbstractTerrestrial arthropods host a variety of helminth parasites, yet quantifying the intensity of infection in these hosts post-mortem is challenging because carcasses may desiccate quickly. We recovered cysticercoids of Hymenolepis diminuta from desiccated flour beetle (Tribolium confusum) carcasses by modifying a published insect rehydration procedure. Without rehydration, carcasses dissected more than 1 day post-mortem had noticeable degradation of cysticercoids. Mild rehydration (soaking in water only for 2 days, or 0.5–10% KOH for 1 h followed by 1 day in water, or 0.5% KOH for 1 day) left carcasses tough and time-consuming to dissect, but all parasites could be recovered and were similar in body size to fresh cysticercoids. Moderate rehydration (5–10% KOH for 1 day) allowed all parasites to be recovered and facilitated dissection by partially dissolving internal organs of the beetle while causing little degradation of the cysticercoids. Harsh rehydration (5–10% KOH for 1 day followed by 5 days in water) not only dissolved internal beetle tissues but also severely damaged cysticercoids, such that parasite counts were unreliable. The degree of initial carcass desiccation had little effect on results following rehydration. However, regardless of treatment used, intact cercomers were rarely retained on rehydrated cysticercoids. Rehydration was less successful on early developmental stages of the parasite, which were recovered reliably only as they neared the cysticercoid stage. This method has utility for studies of parasite-induced mortality by permitting accurate and reliable parasite counts from dead, desiccated hosts.

scholarly journals Mixed infections with Opisthorchis viverrini and intestinal flukes in residents of Vientiane Municipality and Saravane Province in Laos

2005 ◽  
Vol 79 (3) ◽  
pp. 283-289 ◽  
Author(s):  
J.-Y. Chai ◽  
J.-H. Park ◽  
E.-T. Han ◽  
S.-M. Guk ◽  
E.-H. Shin ◽  
...  
Keyword(s):  
Single Dose ◽  
River Basin ◽  
Relative Proportion ◽  
Opisthorchis Viverrini ◽  
Mekong River ◽  
Mixed Infections ◽  
Helminth Parasites ◽  
Intensity Of Infection ◽  
Mekong River Basin ◽  
Helminth Eggs

AbstractFaecal examinations for helminth eggs were performed on 1869 people from two riverside localities, Vientiane Municipality and Saravane Province, along the Mekong River, Laos. To obtain adult flukes, 42 people positive for small trematode eggs (Opisthorchis viverrini, heterophyid, or lecithodendriid eggs) were treated with a 20–30 mg kg−1 single dose of praziquantel and purged. Diarrhoeic stools were then collected from 36 people (18 in each area) and searched for helminth parasites using stereomicroscopes. Faecal examinations revealed positive rates for small trematode eggs of 53.3% and 70.8% (average 65.2%) in Vientiane and Saravane Province, respectively. Infections with O. viverrini and six species of intestinal flukes were found, namely, Haplorchistaichui, H. pumilio, H. yokogawai, Centrocestus caninus,Prosthodendrium molenkampi, and Phaneropsolus bonnei. The total number of flukes collected and the proportion of fluke species recovered were markedly different in the two localities; in Vientiane, 1041 O. viverrini (57.8 per person) and 615 others (34.2 per person), whereas in Saravane, 395 O. viverrini (21.9 per person) and 155207 others (8622.6 per person). Five people from Saravane harboured no O. viverrini but numerous heterophyid and/or lecithodendriid flukes. The results indicate that O. viverrini and several species of heterophyid and lecithodendriid flukes are endemic in these two riverside localities, and suggest that the intensity of infection and the relative proportion of fluke species vary by locality along the Mekong River basin.

Experimental analysis of intraspecific composition in an intertidal gastropod, Littorina unifasciata

1981 ◽  
Vol 32 (4) ◽  
pp. 573 ◽  
Author(s):  
GM Branch ◽  
ML Branch
Keyword(s):  
Food Availability ◽  
Intraspecific Competition ◽  
Field Experiments ◽  
Small Body ◽  
Standing Stock ◽  
Rocky Shores ◽  
Physiological Tolerance ◽  
South Wales ◽  
Body Sizes ◽  
Population Mortality

L. unifasciata dominates the upper levels of rocky shores at Cape Banks, New South Wales. Peak densities of up to 9600 m-2 occur near the centre of the littorine's vertical zonation and are associated with small body sizes. Density declines, and mean size rises, further down and more particularly further up the shore. Largest animals occur at the top of the shore and in areas experiencing strong wave action, where densities are low. Field experiments showed that increase in density results in a decrease in body weight and an increase in mortality. However, even at a density four times that of the natural population, mortality remained remarkably low, and this is probably a key feature allowing L. unifasciata to penetrate high up the shore. L. unifasciata feeds mainly on lichens and food levels are low over most of the zone occupied by this littorine, rising above and below this zone and being particularly high in the supralittoral immediately above the range of L. unifasciata. Thus, food cannot be a factor limiting the height that L. unifasciata extends up the shore. Experimental caging shows that the standing stock of lichen is inversely related to the density of L. unifasciata. The zonation pattern and size gradient of L. unifasciata may be due to a combination of two factors: a decline of body size due to increasing intraspecific competition at higher densities, and the tendency of L. unifasciata to migrate (probably upwards) away from areas of low food availability. The latter was experimentally demonstrated. L. unifasciata suffers from intense intraspecific competition and is responsible for limiting the availability of its food. Its populations are seemingly not regulated by predators. It borders on a zone of high food availability in which there are no important competitors. These are all circumstances favouring range expansion of the species, to the limits of physiological tolerance, to allow the species to capitalize on the adjacent rich food source.

Opisthorchis viverrini: relationships between egg counts, worms recovered and antibody levels within an endemic community in Northeast Thailand

Parasitology ◽  
1991 ◽  
Vol 102 (2) ◽  
pp. 283-288 ◽  
Author(s):  
D. B. Elkins ◽  
P. Sithithaworn ◽  
M. Haswell-Elkins ◽  
S. Kaewkes ◽  
P. Awacharagan ◽  
...  
Keyword(s):  
Relative Intensity ◽  
Worm Burden ◽  
Egg Production ◽  
Epidemiological Studies ◽  
Opisthorchis Viverrini ◽  
Northeast Thailand ◽  
Intensity Of Infection ◽  
Antibody Levels ◽  
Serum Igg Levels ◽  
Total Worm Burden

SUMMARYThree techniques for estimating the intensity of Opisthorchis viverrini infection in individuals from a Northeast That community are compared. Egg counts were determined using a quantitative formalin/ethyl acetate technique, worm burdens were estimated by expulsion chemotherapy and antibody levels were measured by ELISA. Log-transformed worm and egg counts were closely correlated (r = 0·80), suggesting that both measurements provide good assessments of relative intensity of infection. However, no Opisthorchis worms were recovered from 34 people with high egg counts; probably due to problems with the expulsion technique in some individuals. Examination of egg production per fluke indicated that each fluke contributed an average of 180 eggs per gram (epg) of faeces and fecundity was negatively associated with total worm burden. Serum IgG levels correlated significantly with Opisthorchis egg count (r = 0·61) at two independent assessments. Although significant associations were observed between antibody levels and echinostome infection, analysis suggested that these reflected independent associations between these two variables and Opisthorchis infection and age. We conclude that all three measurements are useful for epidemiological studies.

Temperature-Dependent Growth and Production by a Marine Copepod

1981 ◽  
Vol 38 (1) ◽  
pp. 77-83 ◽  
Author(s):  
I. A. McLaren ◽  
C. J. Corkett
Keyword(s):  
Growth Rates ◽  
Life Cycles ◽  
Temperature Dependent ◽  
Marine Copepod ◽  
Development Times ◽  
Body Sizes ◽  
Eurytemora Herdmani ◽  
Growth Production ◽  
Dependent Growth ◽  
Specific Growth Rates

Highly synchronous cohorts of the copepod Eurytemora herdmani at a station near Halifax, Nova Scotia, were followed in samples taken during late July and early August, 1980. Individuals from the same population were reared in the laboratory from copepodite I (CI) to adult in conditions of food satiation. Development times and adult body sizes in nature were about the same as predicted for comparable temperatures in the laboratory. Weight increments between CI and adult male in samples from nature were exponential. Females became heavier, because of eggs, after CIII, but developed more slowly, so that their specific growth rates were about the same as for males. Production estimated from weights and stage increments in successive samples (cohort method) was adequately predicted from biomasses in samples and temperature-dependent development times from the laboratory. Production of egg matter by adult females was also adequately predicted by temperature-dependent growth rates of younger stages. These "rules" of development, growth, and production need wider empirical testing and theoretical justification.Key words: Copepoda, temperature, life cycles, development, growth, production

Plasmodium yoelii nigeriensis: the effect of high and low intensity of infection upon the egg production and bloodmeal size of Anopheles stephensi during three gonotrophic cycles

Parasitology ◽  
1995 ◽  
Vol 111 (5) ◽  
pp. 555-562 ◽  
Author(s):  
J. C. Hogg ◽  
H. Hurd
Keyword(s):  
Egg Production ◽  
Anopheles Stephensi ◽  
Plasmodium Yoelii ◽  
Infected Mosquito ◽  
Intensity Of Infection ◽  
Related Factors ◽  
Low Intensity ◽  
Mosquito Mortality ◽  
Fecundity Reduction

SUMMARYAnopheles stephensi mosquitoes showed a reduction in fecundity over 3 successive gonotrophic cycles, after becoming infected with Plasmodium yoelii nigeriensis. This effect could be observed at high oocyst burdens (> 75) or at low oocyst burdens (mean of 4·36). Mean bloodmeal size of the infected mosquitoes was significantly reduced only when feeding upon a mouse with a high gametocytaemia and the conversion of the bloodmeal into eggs by the infected mosquitoes was disrupted. Patterns of infected mosquito mortality, over the 3 gonotrophic cycles, varied with severity of infection. Although in 1 case increased mortality and decreased bloodmeal size may have affected fecundity, this could not have accounted for all of the observed fecundity reduction. We propose that other, unknown parasite related factors, are involved.

Sign in / Sign up

Export Citation Format

Share Document