A Biological Study of Green Pea) Aphid Acyrthosiphon Pisum (Harris) (on Alfalfa in Mazandaran)

In recent years, green pea aphid acyrthosiphon pisum (Harris) has been identified as one of the important post of alfalfa, and it is active in most parts of Iran in alfalfa farms and causes damage to them including Mazandaran, Fars, Isfahan, Kermanshah, and Eastern Azarbaijan. This aphid is active in two a live winged and alive wingless farms within all farming year. According to studies conducted on this pest biologically, it's maximum activity has been occurred in May and at beginning of July when monthly maximum heat has been in a range from 28 to 30 C and relative humanity in range from 60% to 65%. For this reason maximum damage to the alfalfa product caused by this aphid is accomplished within this time. On the basis of the conduct studies, sexual and adulation steps in this aphid has not been observed in the climatic conditions of Mazandaran. This aphid passes the winter in alive wingless females form. In spring they begin to be active upon favorableness of climatic conditions and generate wangled and wingless individuals by the Parthenogenes thelytoqie /parthenogenesis in spring and are active and reproduce via this method throughout the year in case of existence of the host. In the performed studies, it has been shown that each viviparous female aphid has reproduced 26 to 71 youngs. The young ones have been maturated following 6 to 8 days and their life span has been in a range from 11 to 12 days since birth time