Study On Effects Of Nectar Composition,Rainfall At Pre-flowering And Flowering Stage On Mythimna Separata

Mythimna separata(Walker),is an important migratory agricultural pests.Wang Gaoping(2006)has pointed out that the amount of the first generation armyworm in the wheat field was positively correlated with Astragalus sinicus L.that was the main nectar plant in central and eastern China,nevertheless,it had no correlation with the area of Brassica napus L.in this area from 1950 to 1992.As a supplemental nutrition host of adult M.separata,the effect of nectar plants on the M.separata is much higher than wheat that is the host plants of larvae.Whether rape nectar has an adverse impact on the reproduction of Oriental armyworm(OAW)remains to be seen.The nectar viscosity can exert an effect on the intake of nectar.A moderate amount of rainfall during the periods of pre-flower is beneficial to nectar secretion.In addition,the rainfall of flowering stage can reduce nectar viscosity.The hilly region of Henan province should be the important insect source of the second generation of OAW because the wheat field management is relatively extensive and the distribution of early summer nectar plants is more extensive in this area.Whereas,it's not clear that the effect of the precipitation during the pre-flowering and flowering phase of nectar source plants on the occurrence of armyworm in different regions.In this study,the data relating to the reproduction of the OAW adult that were fed with 8%(w/w)monose(The ratio of glucose to fructose is 1:1)and a series concentration gradient of glucosinolates were measured.Analyzing the influence of the precipitation of florescence(16 April to 15 May–The generation of OAW larvae)and pre-flowering(16 March to 5 April–Overwintering adults migrated to their peak,20 May to 10June–Emergence of adults of the first generation of adult armyworm)on the occurrence of the first generation of larvae and adult OAW and the second generation of the larvae in different hilly regions(The distribution areas of spring and summer nectar plants)in Henan province from 2005 to 2017.The result showed as follows:(1)Effects of Sinigrin hydrate on adult OAWPre-oviposition period of adult OAW: The OAW moth which intake glucosinolate solutions with a concentration of 4mg/g have the longest pre-oviposition period that is 5.10±0.19 d,it is significantly higher than 1mg/g concentration experimental it is significantly higher than 1mg/g concentration experimental group(4.13±0.31d),8mg/g concentration experimental group(4.10±0.31d)and control group(4.10±0.24d).Oviposition period of adult OAW: The OAW moth which intake glucosinolate solutions with a concentration of 4mg/g have the longest oviposition period that can reach to 8.03±0.60 d,it is significantly higher than 1mg/g concentration experimental group(4.83±0.59d),2mg/g concentration experimental group(6.27±0.68d),8mg/g concentration experimental group(4.60±0.41d)and control group(6.30±0.53d).The average amount of egg laying per female adult OAW: The OAW moth which intake glucosinolate solutions with a concentration of 4mg/g have the largest average amount of egg laying per female adult OAW,even up to 1269.60±123.27,it is significantly higher than 1mg/g concentration experimental group(911.57±125.23),8mg/g concentration experimental group(602.37±73.16).Egg hatchability : The OAW moth which intake glucosinolate solutions wit-h a concentration of 2mg/g have the highest egg hatchability,it's 62.01±4.13%,which apparently higher than 8mg/g concentration experimental group(36.41±5.77%).(2)Effects of the precipitation of florescence and pre-flowering on the occurrence of the first generation of larvae and adult OAW and the second generation of the larvae in different hilly regionsAcorrding to the analysis of the correlation between the rainfall in flowering phrase of spring nectar plants(16 March to 5April)and the occurrence of the first and second generation of larvae in different hilly regions in Henan province from 2005 to 2017,we discoverd that there was a prominent negative correlation between the first generation of OAW larvae and the rainfall in flowering phrase of spring nectar plants in the west of Henan province(Sanmenxia and Lushi).On the contrary,there was a conspicuous positive correlation between the second generation of OAW larvae and the rainfall in flowering phrase of spring nectar plants.The precipitation of florescence of spring nectar plants of other flowering periods were not associated with the first and second generation of larvae occurrence.Through analyzing the relationship between rainfall of early flowering(16 March to 5 April)and flowering(20 May to 10 June)of early summer nectar plants and the first generation of OAW moths in different hilly regions in Henan province from 2005 to 2007,we found that there was a prominent negative correlation between the rainfall in flowering phrase of early summer nectar plants and the occurrence of the first generation of adult OAW in the central(Dengfeng,Xinmi,Yuzhou,Lushan)and Midwest(Mengjin,Yanshi,Xin,an,Yiyang,Yichuan,Songxian,Luanchuan,Jiyuan,Ruyang)of Henan province.The precipitation of flowering phrase of early summer nectar plants were not associated with the first generation of adult OAW occurrence.Through analyzing the relationship between rainfall of early flowering(16 March to 5 April)and flowering(20 May to 10 June)of early summer nectar plants and the second generation of OAW larvae in different hilly regions in Henan province from 2005 to 2007,we found that there was a conspicuous positive correlation between the rainfall in early flowering period of early summer nectar plants and the occurrence of the second generation of OAW larvae in the west(Sanmenxia and Lushi)and north((Anyang and Linzhou)of Henan province.The precipitation of flowering phrase of early summer nectar plants were not associated with the second generation of adult OAW occurrence.