Study On Biology And Evolution Of The Different Geographical Populations Of Ctenocephalides Felis Felis

Cat flea(Ctenocephalides felis felis) is one of the important vectors in China, especially in country and in outskirts of cities. The adults of this flea are mainly living in the outside of cats and dogs. By now, there are very little researches on it comparing to other vectors since it is very different to get enough samples. Based on the laboratory population of cat flea reared in ICDC of China CDC and field population from cats in the country village of Beijing, some biological characteristics of cat flea such as fecundity, life cycle, bloody feces, hunger tolerance and engorged quantity and so on were studied using bioassay methods. At the same time, some samples were collected from cat or dogs in the villages or outskirts Beijng, Yunnan, Qingdao, Shanghai and Xinjing respectively, to do some research on the evolution of this species among different regions by ampificationg and analysis internal transcribed apacer 1(ITS-1) gene. Survey was carried out to know the distribution, host type and the seasonal density development of cat flea in Beijing and Qingdao. The main conclusions are as follows:On field survey:there are a lot of domestic dogs in all the surveyed areses,1-2 dogs/home in Beijing,2 dogs/home in Qingdao, and the infection rate of fleas which were collected from dogs were under 20%. The amount of domesic cats were relatively fewer than dogs, there are one or two families raising cats in country of Beijing, and in Qingdao the number may be five. On the contrary, the quantity of wildcat is more, the infection rate of fleas from cats were almost 100%, and the Ct. felis can be survival in all the year round.The average development time of Ct. felis from egg to adult is 18.8d, which is a shorter life cycle than other vectors; The flea egg hatching rate is about 82.3%, cocooning rate is 69.6%, adult emergence rate is 69% and the sex ratio emerged adult is 2.35:1(♀:♂). There was no significant different between the spawning rate of cat flea feeding with the female white rats blood and that of male, so there is no host sex dependence in Ct. felis. The study on relationship between fecundity and blood productivity of Ct. felis showed there is a the double peak curve in the females white rats blood feeding fleas, while there is a single peak curve in the male rats blood feeding fleas, though there is a different shape of the female and male white rat blood supply, they show the same trend that the more fecundity,the more bloody feces productivity and with the significantly reducing fecundity,the blood productivity will also decrease obviously. At the same humidity, hunger endurance of Ct. felis under low temperature is longer than that under high temperature; new emerged no blooding adult can survival for a long time than that of blood-sucking ones. At 17℃, new emerged no blooding adult can live up to 81 days, that is nearly 7 times higher than the flea which only suck in blood once at the same temperature and humidity conditions and also higher than the fleas which is under continuous feeding condition. Different host populations of cat flea show differentiation in weight and host preference. The flea weight of cat host population with 0.241-0.257 mg/flea is heavier than that of white rat host population with 0.167-0.186mg/flea. In addition, the rat hosted flea shows extremely preference to the rats blood, however, the cat hosted flea prefer cat blood. 145 individuals of Ct.felis collected from cat in Beijng, Yunnan, Qingdao, Shanghai and Xinjing were used to amplify ITS-1 gene, and then analysised the molecular characteristics. The result showed that 12 sites emerged mutation, deletion, insertion and others, the largest genetic distance was 0.006. NJ trees and UPGMA trees were constructed to show the difference from different individuals, as we expected, the difference of this gene sequence was very little for the distribution of cat flea is depended on the distribution of cat and dog, which are the main host of cat fles. It is known that where there is human there is cat and dogs, so as the exchange of genes fleas, Ct.felis should be stable within species.