Seasonal Variation of Sex Ratio in Bemisia tabaci on Cotton in Israel

1992 ◽  
Vol 21 (3) ◽  
pp. 556-559 ◽  
Author(s):  
A. R. Horowitz ◽  
D. Gerling
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio ◽  
Bemisia Tabaci

scholarly journals Seasonal variation in the sex ratio of Arctodiaptomus salinus (Copepoda: Calanoida): does it agree with the “cheaper-sex” hypothesis?

2014 ◽  
Vol 36 (6) ◽  
pp. 1413-1418 ◽  
Author(s):  
Raquel Jiménez-Melero ◽  
Juan Diego Gilbert ◽  
Francisco Guerrero
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio

The poinsettia strain of the cotton whitefly,Bemisia tabaci(Homoptera: Aleyrodidae), biological and demographic parameters on poinsettia (Euphorbia pulcherrima) in relation to temperature

1993 ◽  
Vol 83 (4) ◽  
pp. 535-546 ◽  
Author(s):  
A. Enkegaard
Keyword(s):  
Sex Ratio ◽  
Life Span ◽  
Bemisia Tabaci ◽  
Oviposition Period ◽  
Intrinsic Rate Of Increase ◽  
Euphorbia Pulcherrima ◽  
Egg Development ◽  
Net Reproductive Rate ◽  
Rate Of Increase ◽  
Lower Temperature

AbstractBiological characteristics of the poinsettia strain ofBemisia tabaciGennadius were investigated on poinsettia by laboratory experiments at five temperatures (range: 16°C–28°C). In addition, the effect of rearingB. tabacion the two plant species,Nicotiana tabacum(tobacco) (Solanaceae) andEuphorbia pulcherrima(Euphorbiaceae) (poinsettia) was investigated. The temperature-dependencies were established for the developmental time for eggs and egg-to-adult phase, juvenile mortality, adult female life-span, pre-oviposition period, age-specific fecundity, and sex-ratio. The lower temperature thresholds for egg-development, development from egg to adult and for ovipositional adults were estimated as well as the lower temperature threshold for oviposition. The thresholds were 12°C, 14°C, 8°C and 14°C, respectively. Egg-development required 126 day-degrees and the entire development into adults 327 day-degrees. Mortality was highest at 16°C, being 19.3% in the egg-stage and 95% from egg to adult. The pre-oviposition period and the adult life-span were 40 and 360 day-degrees. The age-specific fecundity ofB. tabaciwas described by a temperature-dependent model. The maximum daily fecundity rate was attained after 60 and 125 day-degrees forB. tabacireared on tobacco and poinsettia, respectively. The fecundity was highest forB. tabacireared on poinsettia. The sex-ratio was in favour of females at and above 19°C and increased with temperature. Estimates of the net reproductive rate, the intrinsic rate of increase, the finite rate of increase, the mean generation time and the doubling time were obtained. A positive linear relationship was found between rmand temperature, the values ranging from 0.0012 at 16°C to 0.1263 at 28°C.

Intra- and interspecific competition between biotypes B and Q of Bemisia tabaci (Hemiptera: Aleyrodidae) from Spain

2004 ◽  
Vol 94 (4) ◽  
pp. 369-375 ◽  
Author(s):  
S. Pascual ◽  
C. Callejas
Keyword(s):  
Sex Ratio ◽  
Interspecific Competition ◽  
Bemisia Tabaci ◽  
Interspecific Interactions ◽  
Developmental Rate ◽  
Mixed Cultures ◽  
Progeny Size ◽  
Moderate Effect ◽  
Single And Mixed Cultures ◽  
Biotype B

AbstractBiotypes B and Q of Bemisia tabaci (Gennadius), collected from the islands of Tenerife and Majorca respectively, were exposed to competition conditions on tomato cv. Marmande in the laboratory. Both biotypes were established in single and mixed cultures at different densities. Increased mortality of biotype Q females and immature instars was observed together with a lower rate of fecundity and progeny size compared to biotype B, when reared in single or mixed cultures. The female:male sex ratio of F1 individuals of biotype Q was higher in single than in mixed cultures. However, the sex ratio of F1 individuals of biotype B was the same in single and mixed cultures, suggesting reproductive interference. Whitefly density did not affect interspecific interactions. It had a moderate effect on developmental rate of both biotypes, and on mortality of immature instars and progeny size of biotype B only. The results indicate that under laboratory conditions the studied biotype B should displace biotype Q.

scholarly journals Seasonal variations of childhood Guillain-Barre Syndrome in South west Iran

2018 ◽  
Vol 60 (2) ◽  
pp. 108-112
Author(s):  
Ali A. Momen ◽  
Abdolhussein Shakurnia ◽  
Mahsa Sarrami
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio ◽  
Seasonal Variations ◽  
Acute Flaccid Paralysis ◽  
Guillain Barre Syndrome ◽  
Khuzestan Province ◽  
South West ◽  
Guillain Barré Syndrome ◽  
Different Seasons ◽  
Guillain Barré

Background: It was found that the occurrence of Guillain-Barre Syndrome (GBS) varies in respect tothe month and season; this variation has not been adequately studied.Objective: To determine the month and seasonal variation of GBS in children in the Khuzestanprovince, south west Iran, during a 10-year period (2006-2015).Patients and methods: We extracted data retrospectively from acute flaccid paralysis committeefrom healthcare centers in all cities of the province, over a 10-year period (from January 1, 2006 toDecember 31, 2015). In this study all children under 15 years of age with Guillain-Barre syndromewere surveyed. In order to compare the frequency of GBS in different seasons and months we used theChi Square test.Results: From 187 cases of GBS, 101 (54%) were males, 86 (46%) females with sex ratio 1.17:1. Themean age of the children was 5.39 ± 4.02 years. The highest occurrence of GBS was observed inautumn (32.1%) followed by winter (27.3%). The highest number of cases (28; 15%) occurred inDecember and the lowest (8; 4.3%) in September. There was seasonal (P=0.006) and monthly(P=0.036) variation in occurrence of GBS throughout the year with more prevalence in autumn ,September and December.Conclusion: Our study showed that there is a significant monthly and seasonal variation in childrenwith GBS in Khuzestan province.

scholarly journals Ecology of Phallotorynus pankalos (Cyprinodontiformes: Poeciliidae) in a first-order stream of the upper Paraná Basin

2009 ◽  
Vol 7 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Yzel R. Súarez ◽  
João Paulo da Silva ◽  
Lilian P. Vasconcelos ◽  
William Fernando Antonialli-Júnior
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio ◽  
Population Ecology ◽  
Female Mortality ◽  
Order Stream ◽  
Female Population ◽  
First Order ◽  
Ovary Weight ◽  
Adult Females ◽  
First Reproduction

Some aspects of the population ecology of Phallotorynus pankalos in a first-order stream of the Iguatemi River Basin are described based on samples taken from March/2007 to February/2008. A total of 2680 individuals, including 948 males and 1732 females was collected. Adult females are larger than males; theirs mean fecundity was estimated as 6.5 embryos/female. There was a strong correlation between standard length and ovary weight, relative ovary weight, and number of embryos. The size of the first maturation of 50% of female population was estimated as 18.24 mm of standard lenght. High female mortality was observed after the first reproduction and sex ratio presents seasonal variation with higher female proportion in the winter.

Adaptive Seasonal Variation in the Sex Ratio of Kestrel Broods

1990 ◽  
Vol 4 (2) ◽  
pp. 143 ◽  
Author(s):  
C. Dijkstra ◽  
S. Daan ◽  
J. B. Buker
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio

scholarly journals SEASONAL VARIATION IN SEX RATIO OF FLEDGLING AMERICAN KESTRELS: A LONG TERM STUDY

2002 ◽  
Vol 114 (4) ◽  
pp. 474-478 ◽  
Author(s):  
MATTEO GRIGGIO ◽  
FRANCES HAMERSTROM ◽  
ROBERT N. ROSENFIELD ◽  
GIACOMO TAVECCHIA
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio ◽  
Term Study ◽  
Long Term Study ◽  
American Kestrels

scholarly journals EFFECTS OF STRESSFUL EVENTS IN FRANCE (1968) AND JAPAN (1995) ON THE SEX RATIO AT BIRTH

2016 ◽  
Vol 49 (5) ◽  
pp. 664-674 ◽  
Author(s):  
Victor Grech ◽  
Dorota Zammit ◽  
Hagen Scherb
Keyword(s):  
Public Health ◽  
Seasonal Variation ◽  
Sex Ratio ◽  
Perinatal Mortality ◽  
Stressful Events ◽  
Terrorist Attacks ◽  
Public Health Issue ◽  
Small Male ◽  
Sex Ratio At Birth ◽  
Aum Shinrikyo

SummaryMales are usually born in excess of females. The sex ratio at birth (SR) is often expressed as the ratio of male to total births. A wide variety of factors have been shown to influence SR, including terrorist attacks, which have been shown to reduce SR. This paper reviews the effects on SR outcomes of the stressful events in France in 1968 (in association with the student and worker riots) and in Japan following the Aum Shinrikyo religious cult’s attack on the Tokyo subway using sarin nerve gas in 1995. Both countries displayed seasonal variation in SR. France exhibited a decline in SR in 1968 (p=0.042), with a particularly strong dip in May of that year (p=0.015). For Japan, there was no statistically significant dip for 1995 but there was a significant dip in June of that year (p=0.026). The SR dips follow catastrophic or tragic events if these are perceived to be momentous enough by a given populace. It is believed that SR slumps may be caused by population stress, which is known to lead to the culling of frail/small male fetuses. It has been observed that these fluctuations are comparable in intensity to a substantial proportion of quoted values for perinatal mortality, potentially making this a public health issue.

Sign in / Sign up

Export Citation Format

Share Document