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Dynamics Of Sesamia Inferens In Yangz Hou Area And Biology Of Cotesia Flavipes

Posted on:2021-04-09Degree:MasterType:Thesis
Country:ChinaCandidate:Q Y LiFull Text:PDF
GTID:2393330602485642Subject:Plant protection
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Sesamia inferens was once an occasional secondary pest in China.With the global war ming and changes in rice cultivation system,the damages caused by S.inferenshave gradually increased in parts of China and become an important pest on rice in recent years.Cotesia flavipes is the main larval parasitoids of S.inferens,it is distributed in many countries all over the world and thehost range is relatively wide.In order to grasp the dynamics of S.inferens in the fields,we conducted sex pheromone and light trapping to S.inferens in Ganquan Town and Fangxiang Town,Hanjiang District,Yangzhou.In addition,we conducted a field investigation of S.inferens overwintering and set up 3 photoperiods and 2 temperatures combinations to induce diapause in the laboratory,in order to clarify the overwintering characteristics of S.inferens in the field and whether it can be induced into diapause.For evaluating the biological control potential of C.flavipes,an important parasitic nature enemy of S.inferens,the dynamics in fields and parts of biology of C.flavipe were studied in this paper.The main research results are summarized as follows:1.Sex pheromone and light trapping to S.inferens were conducted in Ganquan Town and Fangxiang Town,hanjiang District,Yangzhou in 2019.The results showed that the peak period of the overwintering generation of adults in Yangzhou were in late April or early May;the 1st generation of S.inferens were in mid-July;the 2nd generation of S.inferens were in mid-August;3rd generation of S.inferens occurred in mid-September,the peak period was in late September or early October,the dynamics of S.inferens showed on light and sex pheromone trapping were relatively consistent.2.The field investigation of overwintering characteristics of S.inerens in 2019 and the diapause induction of S.inferens showed that most of the collected larvae could grow and develop normally,indicated S.inferens was dormant in Yangzhou,but in the combination of light and temperature set manually in the laboratory,when exposed at 20? and 10h light duration,most of S.inferens were in diapause,and when exposed at 23? and 16h light duration,the growth and development of S.inferens were going on normally,therefore,it can be induced into diapause under certain conditions.3.The field investigation in Yangzhou showed that only one kind of parasitic wasp C.flavipes was found in overwintering larvae of S.inferens.The parasitisc rate of C.flavipes in the field is up to 33.33%,and considered to be a do minant parasitic natural enemy of S.inferens.The results of biological investigation showed that the maximum time for C.flavipes to pupate from the larvae collected in the field was no more than 12.7 days,which indicated that C.flavipes is in a dormant state in S.inferens when overwintering.Eight species of lepidopteran larvae were selected for parasitism,and the results showed C.flavipes could only parasitize S.inferens effectively,the parasitism rate and emergance rate was up to 50%and 94%respectively.In addition,when the time of feeding nutrition was 3hours,the average parasitism rate was ashigh as 40%,and the cocooning rate and emergence rate werehigher than that of feeding for 1 and 2hours.Compared with non-feeding nutritions,feeding nutritions obviously prolong the lifespan of the C.flavipes,and the prolongation effect of each treatment is:10%Sophora japonicahoney water>10%pollen liquid>10%lime treehoney water>clear water>non-feed nutritions.
Keywords/Search Tags:Sesamia inferens, Sex pheromone and light trapping, Overwintering characteristics, Diapause induction, Cotesia flavipes, Biology
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