scholarly journals Sperm Production Is Reduced after a Heatwave at the Pupal Stage in the Males of the Parasitoid Wasp Microplitis rufiventris Kok (Hymenoptera; Braconidae)

Insects ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 862
Author(s):  
Ahmed M. El-Sabrout ◽  
Esmat Hegazi ◽  
Wedad Khafagi ◽  
Christophe Bressac
Keyword(s):  
Sex Ratio ◽  
Spodoptera Littoralis ◽  
Pupal Stage ◽  
Parasitoid Wasp ◽  
Adult Males ◽  
Sperm Production ◽  
Microplitis Rufiventris ◽  
Beneficial Insects ◽  
The Many ◽  
Hymenopteran Parasitoids

Understanding reproduction is essential for controlling pests and supporting beneficial insects. Among the many factors allowing optimal reproduction, sperm availability is key to sex ratio control in hymenopteran parasitoids since males are haploid and only females come from fertilization. Microplitis rufiventris (Hymenoptera; Braconidae) is a solitary endoparasitoid of some noctuids. This insect could be used for the control of the cotton leafworm Spodoptera littoralis. Under controlled conditions, sperm quantity was measured in virgin males at 1, 5, 10, and 15 days; it increases in adult males until the fifth day. Sperm stock of control males increased from 2500 at one day to 6700 at 15 days. With the control climatic condition being 25 °C, we tested the effects of a time-limited increase of temperature that can be found in Egypt (36 and 40 °C) during one day at the early pupal stage. Emerging males had 1500 and 420 sperm at 36 and 40 °C, respectively; both lived shorter than the control. The sperm potential of males is dependent on both age and temperature during the early pupal stage. It could have dramatic consequences on the sex ratio of M. rufiventris in natural and controlled populations.

Competition and the superparasitism of Spodoptera littoralis (Boisd.) larvae by Microplitis rufiventris Kok.

1984 ◽  
Vol 103 (1) ◽  
pp. 181-187 ◽  
Author(s):  
E. M. Hegazi ◽  
M. A. Shabaan
Keyword(s):  
Larval Stage ◽  
Spodoptera Littoralis ◽  
Pupal Stage ◽  
Microplitis Rufiventris ◽  
Physical Attack ◽  
First Instar ◽  
Physiological Suppression

SummaryAn experiment to compare the effect of diverse ratios of 0–6 h old Microplitis rufiventris Kok. progeny within Spodoptera littoralis (Boisd.) larvae is described and the results discusssed. Five to 21% of parasite progeny was eliminated during the egg stage. Surplus parasite larvae were eliminated mainly by physical attack, physiological suppression and perhaps by encapsulation. Parasite larvae which escaped competition during their first instar were subjected to physiological suppression. Some of the super-numerary parasite larvae other than the winners survived competition mechanisms and developed in the host haemocoele. Nevertheless, most of these parasites suffered from moulting failure and emergence problems at the end of their endoparasitic development. The development of the winning parasite was retarded by 1–2 days during its egg-larval stage while the duration of its pupal stage was about the same as parasites from singly parasitized hosts.

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 Biology of Diadiplosis multifila (Diptera: Cecidomyiidae) in Planococcus citri under constant temperatures

2019 ◽  
Vol 10 (3) ◽  
pp. 346-352
Author(s):  
Alexandre Martins Dos Santos ◽  
José Eudes De Morais Oliveira ◽  
Andréa Nunes Moreira de Carvalho ◽  
Martin Duarte De Oliveira ◽  
Carla Patrícia Oliveira de Assis ◽  
...  
Keyword(s):  
Life Cycle ◽  
Sex Ratio ◽  
Larval Stage ◽  
Pupal Stage ◽  
Planococcus Citri ◽  
Egg Viability ◽  
Northeast Region ◽  
Embryonic Period ◽  
Semi Arid ◽  
Total Life

Diadiplosis multifila was recently discovered feeding on Planococcus citri eggs in vineyards in the semi-arid northeast region of Brazil. The objective of the present paper was to study the biology of D. multifila in P. citri under constant temperatures of 22, 25, 28, and 31 °C. We evaluated its embryonic stage, egg viability, development period, survival of larva and pupa, longevity, average number of eggs, and sex ratio. D. multifila completed its life cycle in all temperatures except for 31 °C. The length of the embryonic period ranged from 4 to 7 days. The larval stage was longer at a temperature of 22 °C (8.6 days) and shorter at 28 °C (6.4). The pupal stage exhibited durations of 12.9, 10.4, and 8.2 days for temperatures of 22, 25, and 28 °C, respectively. The average viability in the larval stage was 97% and 83% in the pupal stage. The total life cycle took 16.7 (28 °C), 20 (25 °C), and 27 (22 °C) days to complete. The adults lived for approximately 2 days and the females produced on average 34, 25, and 19 eggs at temperatures of 22, 25, and 28 °C, respectively. The sex ratio varied from 0.46 to 0.54.

Contribution of adult sex ratio to trauma and reproductive output in large breeding groups of rhesus macaques (Macaca mulatta)

2021 ◽  
Vol 30 (4) ◽  
pp. 479-492
Author(s):  
J Crast ◽  
MA Bloomsmith ◽  
CM Remillard ◽  
T Meeker
Keyword(s):  
Sex Ratio ◽  
Macaca Mulatta ◽  
Social Dynamics ◽  
Rhesus Macaques ◽  
Well Being ◽  
Primate Research ◽  
Adult Males ◽  
Adult Sex Ratio ◽  
Breeding Groups ◽  
Financial Burdens

Maintaining stable breeding groups of rhesus macaques (Macaca mulatta) can be challenging due to the complex social dynamics and despotic nature of the species. Trauma from aggression is a common problem in rhesus colonies and can cause social disruption, strain veterinary and animal management resources, and potentially affect reproduction. Previous research has shown that increasing the number of non-natal adult males in a breeding group can improve group stability, reduce trauma, and increase reproduction. Here, we used mixed-effects regression models to examine the effects of sex ratio and other factors on trauma and reproduction at the Yerkes National Primate Research Center using a historical dataset made up of four large rhesus groups over an eleven-year period (2003–2013). As expected, sex ratio was a significant predictor for both trauma and reproduction. However, group age since formation was a stronger predictor of trauma frequency and the amount of space available was a slightly better predictor of reproduction than sex ratio or trauma. These results indicate that improving sex ratios can be a viable management strategy to reduce trauma and improve reproduction, particularly when it is difficult to manipulate the group compositions and/or their housing situations. Reducing trauma is a primary goal for rhesus breeding colonies, as it directly impacts the monkeys' health and psychological well-being. Such improvements are necessary for the ethical treatment and care of the animals themselves, but also to reduce financial burdens and maintain a healthy colony for research purposes.

Suitability of Spodoptera littoralis larvae for development of Microplitis rufiventris

1977 ◽  
Vol 89 (3) ◽  
pp. 659-662 ◽  
Author(s):  
E. M. Hegazi ◽  
A. M. El-Minshawy ◽  
S. M. Hammad
Keyword(s):  
Spodoptera Littoralis ◽  
Microplitis Rufiventris ◽  
Larval Instars ◽  
Rate Of Development ◽  
Solitary Parasitoid

SummaryA study of the solitary parasitoid Microplitis rufiventris on larvae of Spodoptera littoralis showed that the age of the host at parasitization influenced the rate of development of the parasite, the percentage of parasitized hosts giving rise to mature parasite larvae, the number of moults subsequent to stinging, duration of larval instars, and the fecundity and longevity of the resulting adult parasites.

When Less Is More: Sex Ratios for the Mass-Rearing of Anastrepha ludens (Diptera: Tephritidae)

2019 ◽  
Author(s):  
G I González-López ◽  
E Solís-Echeverría ◽  
F Díaz-Fleischer ◽  
D Pérez-Staples
Keyword(s):  
Sex Ratio ◽  
Egg Production ◽  
Sex Ratios ◽  
Pupal Stage ◽  
Mass Rearing ◽  
Anastrepha Ludens ◽  
Adult Density ◽  
Genetic Sexing ◽  
Male Harassment ◽  
Less Is More

Abstract Anastrepha ludens (Loew) is one of the most important pests of citrus and mango crops in Mexico. A method used to control this pest is the sterile insect technique, which consists in the mass production, irradiation, and release of insects in affected areas. The production of insects begins with the establishment of colonies to produce eggs, which must be highly fertile to ensure an adequate production of larvae. However, female fecundity and fertility can be affected by adult density and sex ratio, thus an optimal sex ratio in mass-rearing cages must be used. The genetic sexing strain of A. ludens (Tapachula-7) allows the identification of the sex at the pupal stage, making it possible to establish rearing cages with different sex ratios. We determined if different sex ratios have an effect on egg production. Two sex ratios (4♀: 1♂ and 1♀: 1♂) were compared. Fecundity, fertility and survival at different ages were also determined. Higher fertility and fecundity per female were observed at a ratio of 4:1. However, females with higher fecundity had reduced survival probabilities. In conclusion, maintaining colonies with a lower proportion of males in cages ensures a greater fecundity and fertility. Further research is necessary to understand whether results can be attributed to lower male harassment in cages.

THE ENIGMA OF ETHIOPIAN SEX RATIOS AT BIRTH

2016 ◽  
Vol 49 (5) ◽  
pp. 611-622
Author(s):  
Michel Garenne
Keyword(s):  
Sex Ratio ◽  
Urban Areas ◽  
Maternal Education ◽  
Sex Ratios ◽  
Household Wealth ◽  
Poor Nutritional Status ◽  
Linguistic Groups ◽  
Children Ever Born ◽  
Using Data ◽  
The Many

SummaryThis study analysed sex ratios at birth (defined as the number of male births per 100 female births) using data on children ever-born from three censuses conducted in Ethiopia in 1984, 1994 and 2007. The results showed very high values by any standard, with an average of 108.4 for a sample of some 8.2 million births, with somewhat lower values in urban areas. Analysis of socioeconomic correlates revealed that the sex ratio varied very much by household wealth, from about 110 for very poor women to about 102 for wealthier women. The high value of the sex ratio at birth in Ethiopia could be explained by poverty, used as a proxy for poor nutritional status. In multivariate analysis, the effects of living in urban areas and of maternal education were less important than household wealth. Among the many ethno-linguistic groups, the Nilotic family had higher sex ratios than other groups. The results were confirmed using data from DHS surveys conducted in the country, and by the analysis of children still living at time of census.

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