Effects of ultraviolet continuous processing on life table parameters of high generations of Sitobion avenae (Fabricius)

With the appearance of the hole in the ozone and depletion of the stratosphere and the ozone,there is increasing concern about the changing trend in UV-B radiation levels and the impact of increased UV-B on organisms and ecosystems.As the environment is continuously being destroyed,irradiation intensity of UV-B has been enhanced. The aphid,Sitobion avenae( Fabricius),belonging to the suborder Homoptera,and the family Aphididae,is distributed in wheat-producing regions in China. Aphids are parasites of wheat,barley and oats,rice,corn,sugar cane,and grasses in southern China. In the early stages,aphids accumulate on the front or back of leaves,and in the later stages,they accumulate in ear to suck out the fluid,causing the injured plant to experience reduced growth,tiller reduction,1000-grain weight. Aphids are an important pest in grain crops,which are also the dominant plants attacked by aphids that have a short growth cycle,breed quickly,and are highly adaptable. Studies on the effects of UV-B on insects are rare. Thus,additional studies are required to predict the effect of increased UV-B irradiation on the genetic evolution of S. avenae). In order to investigate the effects of ultraviolet continuous processing on the population dynamics of S. avenae after the 20 thgeneration,we adopted certain age life tables to calculate the S. avenae life table parameters and used different strength UV-B( 0,0.50,and 0.70 m W/cm2)to treat S. avenae after the 20 thgeneration. This analysis was intended to provide a theoretical foundation for understanding the long-term development,growth,and reproduction of S. avenae. Changes in the population parameters of the 22 nd generation,the 27 thgeneration,the 32 ndgeneration,the 37 thgeneration,and the intrinsic rate of increase from the first generation to the 37 thgeneration of the aphid were studied. The results showed that:( 1) The average generation cycle( T)of treatments significantly increased and then decreased;( 2) in the low-intensity treatment group,intrinsic rate of increase,net appreciation rate,and weekly growth rate increased first and then decreased,before increasing again; in the high-intensity treatment group, net appreciation rate, weekly growth rate, and fecundity decreased first and then significantly increased,and they all reached the maximum in the 37 thgeneration; and finally,( 3) in the treatment group,the intrinsic rate of increase of the aphids significantly increased and then decreased twice and then