| The amphibians are the important components of the animal resources in the world. They prey on the harmful insects of the farmlands and the natural environments and help human so much that they are named "protects of the cereal". Because of that they played important roles in the production of the farming and forestry animal husbandry and the maintenance balance of the nature. Amphibian populations have dramatically declined globally over the past decades, including a number of species extinction. Many factors may caused the declination such as ultraviolet radiation, habitat damage, biological invasion, environmental pollution, changes of climate and interactions among these factors. However, the newborn infectious diseases also already became substantial causes of the condition. Iridoviruses which may cause the high rates of the incidences and mortality have already spread in the worldwide which are considered the important and direct causes for some of the local population declines. Diseases of the reptiles, amphibians and fish caused by iridovirus in the America, Europe, Asia and Australia are generally popular which led to a variety of amphibian species in serious decline in quantity, or even extinction.In this study we got totally 160 samples of the Rana dybowskii, Rana amurensis,Boulenger Bufo bufogargarizans and Bufo raddei from four different sites of the reserves of Hebei Korean pine reserve-seed tree forests in Heilongjiang Province. Through the modern molecular biology methods we carried the examination of the iridovirus by PCR identification and homology comparision of sequences and made a report on the local situation of the iridovirus disease.Results showed that the positive rate of the Rana dybowskii Rana amurensis,Boulenger Bufo bufogargarizans and Bufo raddei are 75%,77.5%,42.5% and 47.5% separately. Even samples of the same specie from the different sites have difference positive rate.Simultaneously, coinciding their own physiology characteristics and the biological characteristics we established a surveying method of the population quantity of the Rana dybowskii after glancing massive related literatures about the amphibians population quantity surveying in domestic and foreign countries as well as inquiring the expertss that investigated in the amphibians population overseas. In order to make sure the relationships between the population density and the iridovirus, we made a survey of the Rana dybowskii. Also we proposed the feasibility countermeasure to the ecology health of the natural reserve. In further, we made some important references on the biological safety of the species introduction. |
