Effects Of Different Host Plants And Nitrogen Levels On The Development And Fecundity Of Myzus Persicae(Sulzer)

Tobacco Nicotiana tabacum L.has been considered as an excellent host plant of the aphid Myzus persicae(Sulzer)to rear the parasitoid Aphidius gifuensis Ashmead.However,it was necessary to find a more suitable host to instead of tobacco because it spent too more time,energy and cost due to its long growth cycle with high temperature.The number of aphids and the amount of nitrogen on the tobacco were also the problems to be solved.The growth and life table parameters of aphids on three host plants,effects of different initial density aphids on tobacco agronomic traits and different nitrogen levels on the growth and reproduction of aphids were studied.Three plants,tobacco,kale,rape were chosen as aphid hosts in this experiment,under the condition of(25± 0.5)?,(75± 5)%RH,14L:10D.The results showed that the nymph period on kale was the longest(8.61d),the average longevity of the aphids on rape was the shortest(13.63d);the generation time on kale was the longest(16.78d)and the shortest on rape(12.11d);average fecundity per female on rape was the highest(36.29),which on kale was the smallest(11.35).So rape is the most suitable host for the growth and development of aphid,it could be used as a substitute for tobacco to breed aphid.The experimental data of different initial density aphid on tobacco showed the nymph period was the shortest at the initial density 16 aphids per plant.The damages of different initial density aphid to tobacco were mainly indicated by agronomic traits,such as maximum leaf length,leaf width,leaf area;the harm degree depended on the initial amount of aphids.The more initial amount of aphids and staying longer on leaves,the more serious damages were;by fitting the number of aphids on the tobacco at different times,the regression equation of the time t(d)for the number of aphids Nt were:T1(4)Nt=1.23e0.35t,T2(8)Nt=4.18e0.30t,T3(16)Nt=9.98e0.27t,T4(32)Nt=19.31e0.24t,T5(64)Nt=44.41e0.22t.The experimental results of the influence of different nitrogen levels on the growth and reproduction of aphids showed the size of the apterous viviparous female adult was largest,the survival time(28d),the average longevity(11.8d)is the longest,and the average fecundity per female(50.07)is the biggest when the concentration of nitrogen fertilizer is 200mg/L.