The Effect of Temperature on the Sex Ratio of Xenopsylla cheopis Recovered from Live Rats

1945 ◽  
Vol 60 (45) ◽  
pp. 1337 ◽  
Author(s):  
LaMont C. Cole
Keyword(s):  
Sex Ratio ◽  
Effect Of Temperature ◽  
Xenopsylla Cheopis

Effect of temperature of storage and age of fowl eggs on hatchability and sex ratio, growth, and viability of the chickens

1960 ◽  
Vol 11 (4) ◽  
pp. 664 ◽  
Author(s):  
MW McDonald
Keyword(s):  
Relative Humidity ◽  
Sex Ratio ◽  
Storage Temperature ◽  
Lower Number ◽  
The Other ◽  
Effect Of Temperature ◽  
White Leghorn ◽  
Rapid Fall ◽  
Cent Relative Humidity ◽  
Effect Of Age

Fertile White Leghorn eggs were stored for periods ranging from 24 hr to 7 days in environments controlled at 40, 60, or 80°F and 70 per cent. relative humidity. The eggs were then incubated, and observations on numbers of incubator clears and dead embryos at 10 days and again at 17 days, numbers of chickens hatched, weight at hatching, sex ratio, weight of pullets at 14 days of age, and mortalities were recorded. Eggs stored at 40 and 60°F showed no effect of age of egg on number of clears, dead embryos, or number of chickens hatched. Eggs stored at 80°F showed a rapid fall in number of chickens hatched with age of egg before incubation, this effect being produced by increases in number of clears and dead embryos. Storage at 40°F produced a lower number of chickens hatched than at 60°F, owing to a higher number of incubator clears. There was no difference in sex ratio between chickens hatched from eggs stored at 60 and 80°F, neither departing significantly from 50 per cent. pullets. However, storage at 40°F produced significantly more pullets than cockerels, 54.6 per cent. of the chickens being pullets. Storage temperature and age of egg did not affect the hatching weight of the chickens, but when 14 days old, pullets from the eggs stored at 80°F were significantly heavier than pullets from the other groups.

Host location, survival and fecundity of the Oriental rat flea Xenopsylla cheopis (Siphonaptera: Pulicidae) in relation to black rat Rattus rattus (Rodentia: Muridae) host age and sex

2002 ◽  
Vol 92 (5) ◽  
pp. 375-384 ◽  
Author(s):  
S. Mears ◽  
F. Clark ◽  
M. Greenwood ◽  
K.S. Larsen
Keyword(s):  
Sex Ratio ◽  
Rattus Rattus ◽  
Host Choice ◽  
Host Age ◽  
Xenopsylla Cheopis ◽  
Black Rat ◽  
Host Seeking ◽  
Host Sex ◽  
Host Behaviour ◽  
Age And Sex

AbstractHost choice and fecundity are two factors that may contribute to the variation in flea counts observed when assessing the potential risk of flea-borne transmission of pathogens from rodents to humans. Using the black rat, Rattus rattus Linnaeus, as host the effects of age and sex on host choice and fecundity of the Oriental rat flea, Xenopsylla cheopis Rothschild, were examined experimentally at 25°C and 80% rh. During the first two days of emergence from cocoons, female fleas dominated the sex ratio by 4:1 but from the third day onwards this switched to a male-dominated sex ratio of 4:1. The sex of the flea did not influence their host-seeking behaviour. Newly emerged fleas of both sexes were not influenced by the rat‘s presence and at seven days old both sexes demonstrated similar levels of attraction toward the rat host. The sex of the rat did not affect flea host-seeking behaviour. There was a 50–70% decline in the initial number of adult fleas during the first week after their release onto a rat host, and this decline was greatest on juvenile rats. Flea fecundity was also significantly lower on juvenile rat hosts but no differences due to the sex of the rat were observed. This experimental study supports the hypothesis that differences in flea count due to host sex, reported in field surveys, result from sexual differences in host behaviour and not from discriminatory host-seeking behaviour by X. cheopis. Differences in flea count due to host age may be affected by differences in X. cheopis fecundity, which may itself be mediated by host behaviour such as grooming.

Absence of temperature-dependent sex determination in northern populations of two cyprinodontid fishes

1991 ◽  
Vol 69 (2) ◽  
pp. 530-533 ◽  
Author(s):  
D. O. Conover ◽  
S. B. DeMond
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
Life Histories ◽  
Laboratory Experiments ◽  
Fundulus Heteroclitus ◽  
Incubation Temperature ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Young Of The Year ◽  
Embryonic And Larval Development

We tested for an effect of temperature during embryonic and larval development on the sex ratio of offspring in two cyprinodontid fishes (Fundulus heteroclitus and Cyprinodon variegatus) having life histories in which temperature-dependent sex determination might be expected to occur. In both species, field collections showed that as young of the year recruited to the population, the sex ratio did not vary over time, nor did it deviate from 1:1. In laboratory experiments, there was no influence of incubation temperature on sex ratio in either species and sex ratios were near unity in all treatments. Although there was no evidence of temperature-dependent sex determination in the populations we studied, this result should be confirmed on other populations before it is generalized to the species level.

The Effect of Temperature and Humidity upon the Survival of Certain Unfed Rat Fleas

Parasitology ◽  
1932 ◽  
Vol 24 (2) ◽  
pp. 196-209 ◽  
Author(s):  
H. S. Leeson
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Effect Of Temperature ◽  
Maximum Efficiency ◽  
Atmospheric Conditions ◽  
Statistical Measure ◽  
Direct Proportion ◽  
Xenopsylla Cheopis ◽  
Temperature And Humidity ◽  
Xenopsylla Astia

Previous work on the effect of temperature and humidity upon the survival of unfed fleas is criticised in respect of experimental technique. In the present investigation measures have been taken to eliminate as many variables as possible and the methods employed to this end are described.In the experiments, 2027 Xenopsylla cheopis, 999 X. astia and 646 Ceratophyllus fasciatus were employed, all unfed and less than 24 hours old at the commencement of the different experiments. Records were kept individually so that a statistical measure of consistency could be made.The following conclusions have been reached:(1) Duration of life of unfed fleas is not influenced by sex.(2) High temperatures and low humidities tend to shorten life; conversely, low temperatures and high humidities, with a possible optimum of about 90 per cent., tend to produce longer lives.(3) Humidity is at its maximum efficiency in this respect at about 18° C.(4) At 37° C. humidity ceases to have any effect upon the duration of life of unfed fleas, and the evidence suggests that there is also a low temperature at which humidity has no influence upon survival.(5) There is no direct proportion between survival of unfed fleas and saturation deficiency of the atmosphere at any temperature.Comparing the species, it was found that:(1) Ceratophyllus fasciatus was the longest lived, at similar atmospheric conditions.(2) Xenopsylla astia lived longer than X. cheopis at all humidities at 23° C.

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