scholarly journals Effects of temperature and host stage on the parasitization rate and offspring sex ratio ofAenasius bambawaleiHayat inPhenacoccus solenopsisTinsley

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1586 ◽  
Author(s):  
Juan Zhang ◽  
Jun Huang ◽  
Yaobin Lu ◽  
Tianfeng Xia
Keyword(s):  
Sex Ratio ◽  
Mass Rearing ◽  
Phenacoccus Solenopsis ◽  
Offspring Sex Ratio ◽  
Parasitization Rate ◽  
Offspring Sex ◽  
Laboratory Results ◽  
Host Stage ◽  
Effects Of Temperature ◽  
Temperature Exposure

Temperature and host stage are important factors that determine the successful development of parasitoids.Aenasius bambawaleiHayat (Hymenoptera: Encyrtidae) is a primary parasitoid of the newly invasive mealybug,Phenacoccus solenopsisTinsley (Hemiptera: Pseudococcidae). The effects of temperature on the parasitic characteristics ofA. bambawaleihave seldom been investigated. In the study, we explored the effects of temperature, exposure time, and host stage on the parasitization rate and offspring sex ratio (female to male) ofA. bambawaleiunder laboratory conditions. The laboratory results showed that the successful parasitization rate ofA. bambawaleiincreased with higher temperatures and older host stages. When the parasitoids were exposed to 36 °C for 24 h, the parasitization rate of female adults (52%) was nearly two times that of 3rd instar nymphs. Additionally, heat stress duration and host stage resulted in an increase in the offspring sex ratio ofA. bambawalei. WhenA. bambawaleiwas exposed to 36 °C for 24 h, the offspring sex ratio increased dramatically to 81.78% compared with those exposed for 12 h, and it increased to 45.34% compared with those exposed for 16 h. The offspring sex ratio was clearly higher when the host stage was an adult female mealybug Our findings provide important guidance for the mass rearing and field releases ofA. bambawaleifor the management ofP. solenopsisin the future.

Host size-dependent sex allocation behaviour in a parasitoid: implications forCatolaccus grandis(Hymenoptera: Pteromalidae) mass rearing programmes

1998 ◽  
Vol 88 (1) ◽  
pp. 37-45 ◽  
Author(s):  
K.M. Heinz
Keyword(s):  
Biological Control ◽  
Sex Ratio ◽  
Sex Allocation ◽  
Sex Ratios ◽  
Boll Weevil ◽  
Mass Rearing ◽  
Host Size ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Control Programmes

AbstractAn often encountered problem associated with augmentative and inundative biological control programmes is the high cost of producing sufficient numbers of natural enemies necessary to suppress pest populations within the time constraints imposed by ephemeral agroecosystems. In many arrhenotokous parasitoids, overproduction of males in mass-rearing cultures inflates costs (per female) and thus limits the economic feasibility of these biological control programmes. Within the context of existing production technologies, experiments were conducted to determine if the sex ratio ofCatolaccus grandis(Burks), an ectoparasitoid of the boll weevilAnthonomous grandisBoheman, varied as a function of boll weevil larval size. Results from natural and manipulative experiments demonstrate the following behavioural characteristics associated with C.grandissex allocation behaviour: (i) femaleC. grandisoffspring are produced on large size hosts and male offspring are produced on small hosts; (ii) whether a host is considered large or small depends upon the overall distribution of host sizes encountered by a female parasitoid; and (iii) female parasitoids exhibit a greater rate of increase in body size with host size than do male parasitoids. The observed patterns cannot be explained by sex-specific mortality of immature parasitoids developing on the different host size categories. In subsequent experiments, laboratory cultures ofC. grandisexposed daily to successively larger sizes ofA. grandislarvae produced successively greater female biased offspring sex ratios, cultures exposed daily to successively smaller sizes of host larvae produced successively greater male biased offspring sex ratios, and cultures exposed daily to equivalent host size distributions over time maintained a uniform offspring sex ratio. By increasing the average size ofA. grandislarval hosts exposed toC. grandisby 2.5 mg per day in mass rearing cultures, the percentage of male progeny can be reduced from 33% to 23% over a period of four consecutive exposure days.

EFFECTS OF ADULT NUTRITION ON LONGEVITY, FECUNDITY, AND OFFSPRING SEX RATIO OF TRICHOGRAMMA MINUTUM RILEY (HYMENOPTERA: TRICHOGRAMMATIDAE)

1995 ◽  
Vol 127 (2) ◽  
pp. 245-254 ◽  
Author(s):  
J.A. Leatemia ◽  
J.E. Laing ◽  
J.E. Corrigan
Keyword(s):  
Sex Ratio ◽  
Mass Rearing ◽  
Progeny Production ◽  
Short Term ◽  
Offspring Sex Ratio ◽  
Offspring Production ◽  
Offspring Sex ◽  
Trichogramma Minutum ◽  
Potential Benefits

AbstractThe role of adult nutrition in longevity, progeny production, and offspring sex ratio of Trichogramma minutum Riley was examined. On average, honey-fed females lived 26.4 days and produced 260 offspring; unfed females lived 3.5 days and produced 80 offspring. Feeding on fructose or sucrose also significantly increased longevity and fecundity over unfed females (fructose, 23 days and 230 offspring; sucrose, 21 days and 230 offspring) but to a lesser degree than feeding on pure honey. Females fed yeast suspension or water had no significant increases in longevity or fecundity compared to unfed females. Offspring sex ratios of long-lived females were male-biased (50–62% males), those of short-lived females were female-biased (74–82% females). Lifetime reproduction of honey-fed females was highest at 20–25 °C and relative humidities of 20–80%, but short-term offspring production (during the first 2 days after emergence) was highest at 30 °C and 60–80% RH. Females that had access to honey for only a 24-h period did not increase their offspring production over the first 4 days of their lives when compared to unfed females. The potential benefits of feeding adult T. minutum for mass-rearing and field release are discussed.

Offspring sex ratio in moose Alces alces in relation to paternal age: an experiment

2004 ◽  
Vol 10 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Bernt-Erik Sæther ◽  
Erling J. Solberg ◽  
Morten Heim ◽  
John E. Stacy ◽  
Kjetill S. Jakobsen ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Alces Alces ◽  
Paternal Age ◽  
Offspring Sex Ratio ◽  
Offspring Sex

Breeding system can affect the offspring sex ratio in Syrian hamsters

2011 ◽  
Vol 45 (1) ◽  
pp. 55-57 ◽  
Author(s):  
M O M Chelini ◽  
N L Souza ◽  
E Otta
Keyword(s):  
Sex Ratio ◽  
Breeding System ◽  
Offspring Sex Ratio ◽  
Syrian Hamsters ◽  
Offspring Sex

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.

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