On the occurrence of Corynosoma spp. (Acanthocephala) in ringed seals (Pusa hispida) in the Bothnian Bay, Finland

1980 ◽  
Vol 58 (2) ◽  
pp. 298-303 ◽  
Author(s):  
Eero Helle ◽  
E. Tellervo Valtonen
Keyword(s):  
Small Intestine ◽  
Sex Ratio ◽  
Anterior Part ◽  
Intensity Of Infection ◽  
Factors Affecting ◽  
Young Females ◽  
Ringed Seals ◽  
Pusa Hispida ◽  
Gravid Females ◽  
Bothnian Bay

The occurrence, location, sex ratio, growth, and development of Corynosoma strumosum and Corynosoma semerme were studied in 29 Baltic ringed seals, Pusa hispida botnica, in October–November 1977. The prevalence of infection was 96.5% for both species, the intensity of infection being 68(1 to 324) per infected seal in C. strumosum and 140 (1 to 1230) in C. semerme. Of the C. strumosum, 99% were in the small intestine; the remainder, together with 97% of the C. semerme, were distributed from the caecum to the rectum. The numbers of C. strumosum increased along the small intestine, and although the sex ratio remained constant, young females were more numerous in the anterior part of the intestine and gravid females more numerous distally. Factors affecting the numbers and proportions of the Corynosoma species are discussed with reference to their development and the progress of infection in the intestine of the ringed seal.

Aerial census of ringed seals Pusa hispida basking on the ice of the Bothnian Bay, Baltic

Ecography ◽  
1980 ◽  
Vol 3 (3) ◽  
pp. 183-189 ◽  
Author(s):  
Eero Helle
Keyword(s):  
Ringed Seals ◽  
Pusa Hispida ◽  
Bothnian Bay

Comparison between spring and autumn infection by Corynosoma (Acanthocephala) in the ringed seal Pusa hispida in the Bothnian Bay of the Baltic Sea

Parasitology ◽  
1981 ◽  
Vol 82 (2) ◽  
pp. 287-296 ◽  
Author(s):  
Eero Helle ◽  
E. Tellervo Valtonen
Keyword(s):  
Baltic Sea ◽  
Feeding Habits ◽  
Ringed Seal ◽  
The Other ◽  
The Baltic Sea ◽  
Rate Of Development ◽  
Ringed Seals ◽  
Pusa Hispida ◽  
The Baltic ◽  
Bothnian Bay

SUMMARYCorynosoma spp. (Acanthocephala) infection in ringed seals (Pusa hispida) is compared in spring and in autumn in the Bothnian Bay, northern Baltic Sea. The material consists of more than 13400 specimens: 7590 from the intestines of 13 seals captured in April and May 1978 and 5850 from 29 seals captured in October and November.Corynosoma strumosum infection had approximately the same intensity in spring and autumn (mean 76 and 66 individuals/infected seal, maxmum 313 and 324 individuals, respectively). C. semerme specimens, on the other hand, were 37 times more numerous in spring than in autumn (504 compared with 136/infected seal, maximum 1700 and 1230 individuals, respectively). The ratio of C. strumosum to C. semerme was 1:6·3 in spring and 1:2·0 in autumn, as calculated from the total material. Corynosoma infection was more recent on average in spring than in autumn, as judged both from the proportion of males and immature females and from the distribution of C. semerme in the intestine. The feeding habits of the ringed seals and the rate of development of Corynosoma infection are discussed.

scholarly journals Factors affecting the biology of Pachycrepoideus vindemmiae (Hymenoptera: Pteromalidae) on spotted-wing drosophila (Drosophila suzukii)

2019 ◽  
Author(s):  
Cherre S. Bezerra Da Silva ◽  
Briana E. Price ◽  
Alexander Soohoo-Hui ◽  
Vaughn M. Walton
Keyword(s):  
Sex Ratio ◽  
Spotted Wing Drosophila ◽  
Host Feeding ◽  
Drosophila Suzukii ◽  
Factors Affecting ◽  
Intrinsic Factors ◽  
Young Females ◽  
Biocontrol Potential ◽  
Host Killing ◽  
The Impact

AbstractPachycrepoideus vindemmiae is a parasitoid of the invasive spotted-wing drosophila (SWD, Drosophila suzukii) in the U.S. Few studies have addressed interactions between these two species and little is known about the potential of this parasitoid as a biocontrol agent of SWD. Here, we investigated the impact of extrinsic and intrinsic factors on life-history traits of P. vindemmiae. Both constant (entire adulthood) and limited (30 minutes) supply of water + honey, honey, or host increased parasitoid survival compared to controls (water or fasting). Water + honey caused the highest parasitoid survivals (35-60 days), independent of supply period, sex, and host availability. Females were intrinsically more resistant to water and honey scarcity than males, and host-feeding elevated such resistance even higher. Constant supply of honey supported the highest host-killing capacity (ca. 600 SWD pupae/wasp). However, in young females (4-9 days old), such honey effect was insignificant while water deprivation (either with or without honey) resulted in the highest host-killing potential. This indicate that although sugar becomes a critical nutritional resource as females age, young females depend more on water than sugar. No effect of water nor honey was observed on the sex ratio of young females, but when we considered the entire adulthood honey supply produced the lowest proportion of females (0.50), independent of water availability. Such reduction derived from sperm depletion, likely caused by both lack of re-mating and higher fecundity in honey-fed wasps. Neither water nor honey affected parasitoid emergence rate (0.97), independent of female age. Based on survival and host-killing capacity, we conclude that P. vindemmiae has a tremendous biocontrol potential against SWD. Both limited and constant supply of water, sugar, and host increase parasitoid survival, while constant supply of water and/or honey enhance its host-killing potential and decrease sex ratio depending on mother age.

Population parameters of ringed seals (Phoca hispida Schreber, 1775) in the Svalbard area

1987 ◽  
Vol 65 (4) ◽  
pp. 1021-1027 ◽  
Author(s):  
Christian Lydersen ◽  
Ian Gjertz
Keyword(s):  
Sex Ratio ◽  
Ringed Seal ◽  
Adult Males ◽  
Population Parameters ◽  
Phoca Hispida ◽  
Age Class ◽  
Ringed Seals ◽  
Males And Females ◽  
The Mean ◽  
Sexually Mature

Samples were taken from 284 ringed seals (Phoca hispida) in the Svalbard area during April–July 1981 and March–April 1982. The age of 283 seals was determined by reading annuli in the cementum of the canine teeth. The mean age of the males was 11.3 years, and of the females, 14.9 years. Females were found to be significantly older than males. The mean length of sexually mature ringed seals was 128.9 cm for both sexes. The mean weight of adult males and females was 53.5 and 61.4 kg, respectively. Females were found to be significantly heavier than males. The sex ratio was 47.8% males and 52.2% females. Studies of microscopic sections of testis and epididymis from ringed seal males showed that 63, 75, and 80% of 5-, 6-, and 7-year-old animals, respectively, were sexually mature. The weights of testis and epididymis, diameters of tubuli, and the size of testis all showed a marked increase in the 5-year age-class. Macroscopic sections of ovaries from ringed seal females showed that 20, 60, and 80% of 3-, 4-, and 5-year-old animals, respectively, were sexually mature. The size of the ovaries showed a marked increase in the 5-year age-class. The ovulation rate of ringed seals from Svalbard was calculated to be 0.91.

scholarly journals Population structure and reproductive characteristics of the silky shark Carcharhinus falciformis (Müller & Henle, 1839) (Carcharhiniformes: Carcharhinidae) off the coast of Oaxaca, Mexico

2017 ◽  
Vol 44 (3) ◽  
pp. 513-524
Author(s):  
María del Carmen Alejo-Plata ◽  
Miguel Ángel Ahumada-Sempoal ◽  
José Luis Gómez-Márquez ◽  
Adrián González-Acosta
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Seasonal Changes ◽  
Sexual Maturity ◽  
Size Structure ◽  
Landing Sites ◽  
Silky Shark ◽  
Oceanic Species ◽  
Carcharhinus Falciformis ◽  
Gravid Females

Carcharhinus falciformis is an abundant oceanic species, which occurs in equatorial and tropical zones, with an important catch in the Atlantic and Pacific coasts of Mexico. Samples were taken from December 2000 to December 2007 in four landing sites of the artisanal fleet on the coast of Oaxaca. During the period of study 1236 specimens (602 females and 634 males) of C. falciformis were registered. Total length (TL) ranged from 49 to 217 cm for females (mean = 111.3 cm) and from 59 to 265 cm for males (mean = 111.7 cm). The sex ratio of females to males was 1:1 ( 2 0.05 = 0.78, P > 0.05). The present data suggest a size at first sexual maturity of about 184.8 cm TL for females and 178.5 cm TL for males. The catches were composed mainly of young. In the 52 gravid females examined, the average number of embryos per female was seven; with a range of 3-14 embryos. Mean TL of embryos ranged from 10 to 66 cm with evidence of seasonal changes in the size structure. Results obtained showed that C. falciformis gives birth most of the year, with the highest proportion of births during the rainy season (May to October).

Seasonal habitat use of a lagoon by ringed seals Pusa hispida in Svalbard, Norway

2021 ◽  
Author(s):  
J Vacquié-Garcia ◽  
C Lydersen ◽  
E Lydersen ◽  
GN Christensen ◽  
C Guinet ◽  
...  
Keyword(s):  
Habitat Use ◽  
Ringed Seals ◽  
Pusa Hispida ◽  
Seasonal Habitat Use

Factors Affecting Sex Ratio

1975 ◽  
Vol 292 (12) ◽  
pp. 650-651 ◽  
Keyword(s):  
Sex Ratio ◽  
Factors Affecting

scholarly journals Maternal Diet and Other Factors Affecting Offspring Sex Ratio: A Review

2004 ◽  
Vol 71 (4) ◽  
pp. 1063-1070 ◽  
Author(s):  
Cheryl S. Rosenfeld ◽  
R. Michael Roberts
Keyword(s):  
Sex Ratio ◽  
Maternal Diet ◽  
Offspring Sex Ratio ◽  
Factors Affecting ◽  
Offspring Sex

scholarly journals Studies on Absorption of Drugs. VIII. Physicochemical Factors affecting the Absorption of Sulfonamides from the Rat Small Intestine

1973 ◽  
Vol 21 (10) ◽  
pp. 2309-2322 ◽  
Author(s):  
TAKASHI MORISHITA ◽  
MASARU YAMAZAKI ◽  
NOBORU YATA ◽  
AKIRA KAMADA
Keyword(s):  
Small Intestine ◽  
Rat Small Intestine ◽  
Factors Affecting ◽  
Physicochemical Factors
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