Effects Of Ultraviolet Continuous Processing On Population Of Sitobion Avenae(Fabricius) And Aphidius Gifuensis Ashmead

Sitobion avenae?Fabricius?is one of the most important pest in agricultural yield.It feeds on leaves and stems through sucking mouthparts,and then moves on ear of wheat after heading stage;Not only can it causes enormous loss,but also it may cause farmers to reap nothing at harvest time and even spread plant viruses.It belongs to typical R-strategist because of its small size and high reproductive rate and Sitobion avenae is a good material for studying environmental stress.Our research team conducted a preliminary study on different UV intensity,different irradiation time,interaction of irradiation intensity and irradiation time,established experimental conditions which represented the average of current global UV irradiation intensity and rised of 3 degrees Celsius for future global temperature.Our team has has studied the adaptability of 17 generations of aphids under this test conditions.Whether subsequent generations of aphids have adapted to this environmental condition is the scientific issue of this study.Aphidius gifuensis is natural predator of aphids,and can lay its eggs in the host,allows the hatched larvae to feed the tissues of the pests,thereby achieving biological control.Biological control has the advantage of no pollution for the environment.However,both Aphidius gifuensis and Sitobion avenae are subject to UV-induced stress under natural conditions,and how the parasitism rate,emergence rate,and weight of newly emerged parasitoids change during the increase of UV-intensity.It is worth our attention.This experiment continued the previous generation of the 17^th generation studies using ultraviolet rays irradiated by adult.Each generation of adult was irradiated with ultraviolet light of different intensity for 48 hours?16 hours per day?,and then picked up after experiencing UV-B radiation.The 22^nd generation,the 27^th generation,the 32^nd generation,and the 37^th generation of first instar nymph were performed life table studies.Recording the life table and compare the changes with the control group.We used Aphidius gifuensis to parasit the 30^th,34^th and 38^th generations of Sitobion avenae and counted the parasitic rate,emergence rate,and weight of the parasitized bees.The research results provide theoretical basis for the study of environmental stress and provide basic information and basis for practical application of research and development.The result is as follows:1.After UV-B treatment of Sitobion avenae,mean generation time?T?of treatment was significantly increased and then decreased in the same UV-B radiation intensity among different generations.In the low-intensity treatment group,the intrinsic rate of increase?r_m?,net reproductive rate?R₀?,and finite rate of increase???all showed a trend of increasing first,then decreasing and then increasing.In the high-intensity treatment group the intrinsic rate of increase?r_m?,net reproductive rate?R₀?,and finite rate of increase???decreased first and then significantly increased,and both reached the maximum at the 37^th generation.The reproductive parameters of the offspring population also changed significantly.In the low-intensity treatment group,adult longevity?L?,fecundity?F?,and Ovi-days first increased significantly,then decreased and then increased.The adult longevity?L?and fecundity?F?all reached the maximum at the 27^th generation,and the Ovi-days reached the maximum at the37^th generation.In the high-strength treatment group,the adult longevity?L?and Ovi-days of the larvae increased from the 22^nd generation to the 37^th generation,and the fecundity?F?first decreased and then increased significantly.2.The shape parameters of the survival curve of c were all greater than 1,indicating that the death occurred mainly in the later stage of growth and development.The analysis of b values of different generations revealed that the b values of different generations increased first and then decreased under low-intensity treatments,indicating that the survival rate showed a trend of increasing first and then decreasing,reaching the maximum value at the27^th generation and not obvious with the 32^nd and 37^th generations.The b value under high-intensity treatment showed an increasing trend all the time,indicating that as the continuity of the generation,the survival rate showed an increasing trend,and the adaptability increased.3.Under different intensity of UV-B radiation,the reproductive value of increased with the increase of the age,and it reach the maximum value at the stage of adult,which had the biggest contribution to the future population.Under the same generation of different treatments,as the generations increased,the high-strength treatment group of the 32ⁿdd generation and the 37^th generation in the reproductive stage was more than low-intensity treatment group and control group.Under the same treatment of different generations,the low-strength treatment constitutes the saddle-shaped rule that the reproductive value of the pupa increases first,then decreases,and then rises.The high-strength treatment composition first decreases and then rises in the reproductive value of the adult period.The same treatment of different generations,with the rise of generations,adult contribution period first increased and then decreased.4.From 1^st generation to 37^th generation,the r_m value at 37^th generation is higher than other generations in treatment group.5.Different degrees of UV treatment have significant influence on the weight and parasitism rate,and have no significant effect on the emergence rate;the indirect effects of UV-B-treated Sitobion avenae on Aphidius gifuensis:parasitism rate and body weight were significantly affected by Sitobion avenae after 30^th generation UV treatment.The parasitism rate and body weight were not significantly affected by Sitobion avenae after 34^thh generation UV treatment.After the parasitism of the 38^th UV-treated Sitobion avenae,the effect on the parasitism rate was significant,with no significant effect on the body weight,and had no significant effect on the emergence rate;UV-B treatment and the UV-B treatment of Sitobion avenae were different.The tuberculosis will have a significant effect on the body weight and parasitism rate.There is an interaction between the two treatments.In summary,the following conclusions are drawn:1.The Sitobion avenae has been adapted to the high UV intensity after 37 generations of UV treatment,and its adaptation process is ladder type.2.UV rays can affect the natural enemies-the survival of parasitoids.This shows that global warming,increasing of UV-B intensity is so strong on the selective pressure of biology.