scholarly journals Conspecific and heterospecific host discrimination in two parasitoid species of the mealybug Pseudococcus viburni, the solitary Leptomastix epona and the gregarious Pseudaphycus flavidulus

2017 ◽  
Vol 18 ◽  
pp. 17 ◽  
Author(s):  
F. Karamaouna ◽  
M.J.W. Copland
Keyword(s):  
Sex Ratio ◽  
Potential Effect ◽  
Time Interval ◽  
Host Discrimination ◽  
Parasitoid Species ◽  
Solitary Parasitoid ◽  
Secondary Sex Ratio ◽  
Gregarious Parasitoid ◽  
Pseudococcus Viburni ◽  
Augmentative Releases

Leptomastix epona (Walker) and Pseudaphycus flavidulus (Brèthes) (Hymenoptera: Encyrtidae) are endoparasitoids of the mealybug Pseudococus viburni (Signoret) (Hemiptera: Pseudococcidae). Leptomastix epona is a solitary parasitoid originating from Europe and P. flavidulus is a gregarious parasitoid from South America. Conspecific and heterospecific host discrimination was examined between unparasitised female adult mealybugs and others already parasitized, at different time intervals between the primary and the following oviposition. Female wasps of L. epona discriminate between unparasitized hosts and hosts parasitized 0-96 hours previously by a conspecific selecting more often the first over the latter for oviposition. Females of P. flavidulus discriminate between unparasitized hosts and hosts parasitized prior to 0-72 hours by a conspecific. Conspecific superparasitism also occurs in both parasitoid species. The secondary sex ratio of L. epona and the clutch size of P. flavidulus are not affected by superparasitism whereas the secondary sex ratio of P. flavidulus in superparasitized hosts is more male biased than in single parasitized hosts. The solitary parasitoid L. epona does not discriminate between unparasitized hosts and hosts parasitized by P. flavidulus 0-3 or 24 hours previously. Nevertheless the gregarious parasitoid P. flavidulus discriminates between unparasitized hosts and hosts parasitized by L. epona 0-3 hours earlier, but it oviposits without discrimination in hosts heterospecifically parasitized 24 hours beforehand. When multiparasitism occurs at 0-3 hours after the first oviposition, L. epona is a superior competitor regardless of which species oviposits first. However, when the time interval between the two ovipositions is 24 hours, the probability of the offspring of P. flavidulus winning the competition with L. epona increases when either species oviposits first. The potential effect of multiparasitism on parasitoid coexistence is discussed in relation to prospects for multiplespecies introductions or augmentative releases for the biological control of the mealybug.

scholarly journals Maternal exposure to airborne polychlorinated biphenyls (PCBs) and risk of adverse birth outcomes

2021 ◽  
Author(s):  
Ane Bungum Kofoed ◽  
Laura Deen ◽  
Karin Sørig Hougaard ◽  
Kajsa Ugelvig Petersen ◽  
Harald William Meyer ◽  
...  
Keyword(s):  
Birth Weight ◽  
Preterm Birth ◽  
Sex Ratio ◽  
Polychlorinated Biphenyls ◽  
Birth Outcomes ◽  
Gestational Age ◽  
Small For Gestational Age ◽  
Maternal Exposure ◽  
Adverse Birth Outcomes ◽  
Secondary Sex Ratio

AbstractHuman health effects of airborne lower-chlorinated polychlorinated biphenyls (LC-PCBs) are largely unexplored. Since PCBs may cross the placenta, maternal exposure could potentially have negative consequences for fetal development. We aimed to determine if exposure to airborne PCB during pregnancy was associated with adverse birth outcomes. In this cohort study, exposed women had lived in PCB contaminated apartments at least one year during the 3.6 years before conception or the entire first trimester of pregnancy. The women and their children were followed for birth outcomes in Danish health registers. Logistic regression was performed to estimate odds ratios (OR) for changes in secondary sex ratio, preterm birth, major congenital malformations, cryptorchidism, and being born small for gestational age. We performed linear regression to estimate difference in birth weight among children of exposed and unexposed mothers. All models were adjusted for maternal age, educational level, ethnicity, and calendar time. We identified 885 exposed pregnancies and 3327 unexposed pregnancies. Relative to unexposed women, exposed women had OR 0.97 (95% CI 0.82, 1.15) for secondary sex ratio, OR 1.13 (95% CI 0.76, 1.67) for preterm birth, OR 1.28 (95% CI 0.81, 2.01) for having a child with major malformations, OR 1.73 (95% CI 1.01, 2.95) for cryptorchidism and OR 1.23 (95% CI 0.88, 1.72) for giving birth to a child born small for gestational age. The difference in birth weight for children of exposed compared to unexposed women was − 32 g (95% CI—79, 14). We observed an increased risk of cryptorchidism among boys after maternal airborne LC-PCB exposure, but due to the proxy measure of exposure, inability to perform dose–response analyses, and the lack of comparable literature, larger cohort studies with direct measures of exposure are needed to investigate the safety of airborne LC-PCB exposure during pregnancy

Does preconception stress alter the secondary sex ratio?

2011 ◽  
Vol 96 (3) ◽  
pp. S154
Author(s):  
R.J. Chason ◽  
R. Sundaram ◽  
G.M. Buck Louis ◽  
J.H. Segars ◽  
C. Pyper
Keyword(s):  
Sex Ratio ◽  
Secondary Sex Ratio

scholarly journals Is biasing offspring sex ratio adaptive? A test of Fisher's principle across multiple generations of a wild mammal in a fluctuating environment

2018 ◽  
Vol 285 (1891) ◽  
pp. 20181251 ◽  
Author(s):  
Andrea E. Wishart ◽  
Cory T. Williams ◽  
Andrew G. McAdam ◽  
Stan Boutin ◽  
Ben Dantzer ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrels ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Adult Sex Ratio ◽  
Secondary Sex Ratio ◽  
North American Red Squirrels ◽  
Negative Frequency Dependent Selection ◽  
Fisher’S Principle

Fisher's principle explains that population sex ratio in sexually reproducing organisms is maintained at 1 : 1 owing to negative frequency-dependent selection, such that individuals of the rare sex realize greater reproductive opportunity than individuals of the more common sex until equilibrium is reached. If biasing offspring sex ratio towards the rare sex is adaptive, individuals that do so should have more grandoffspring. In a wild population of North American red squirrels ( Tamiasciurus hudsonicus ) that experiences fluctuations in resource abundance and population density, we show that overall across 26 years, the secondary sex ratio was 1 : 1; however, stretches of years during which adult sex ratio was biased did not yield offspring sex ratios biased towards the rare sex. Females that had litters biased towards the rare sex did not have more grandoffspring. Critically, the adult sex ratio was not temporally autocorrelated across years, thus the population sex ratio experienced by parents was independent of the population sex ratio experienced by their offspring at their primiparity. Expected fitness benefits of biasing offspring sex ratio may be masked or negated by fluctuating environments across years, which limit the predictive value of the current sex ratio.

scholarly journals Secondary sex ratio of nestlings of the blackbird (Turdus merula)

2016 ◽  
Vol 23 ◽  
pp. 69-73
Author(s):  
Piotr Nowacki ◽  
Piotr Piliczewski ◽  
Tomasz Rek ◽  
Beata Kirjaka ◽  
Dariusz Wysocki
Keyword(s):  
Sex Ratio ◽  
Turdus Merula ◽  
Secondary Sex Ratio

scholarly journals Secondary sex ratio in relation to exposures to polychlorinated biphenyls, dichlorodiphenyl dichloroethylene and methylmercury

2017 ◽  
Vol 76 (1) ◽  
pp. 1406234 ◽  
Author(s):  
Clara Amalie Gade Timmermann ◽  
Anna L. Choi ◽  
Maria Skaalum Petersen ◽  
Flemming Nielsen ◽  
Esben Budtz-Jørgensen ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Polychlorinated Biphenyls ◽  
Secondary Sex Ratio
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