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Comparison Of Emergence Of The Overwintering Generation And Correlation Between Fecundity And Body Size Between Two Host Races Of Chilo Suppressalis

Posted on:2018-04-24Degree:MasterType:Thesis
Country:ChinaCandidate:R ChenFull Text:PDF
GTID:2323330515997467Subject:Agricultural Entomology and Pest Control
Abstract/Summary:PDF Full Text Request
Sympatric speciation is one of the basic way of speciation.Studying sympatric speciation is significant for understanding ecological speciation.The striped stem borer Chilo suppressalis Walker is an important pest in the agriculture production,which could divided into rice race and water-oat race according to the different food they fed on.While there is still a lack of accurate observations of the emergence time of the adult.In addition,the difference of fecundity and body size between the host races of C.suppressalis could not be used as sufficient evidences for the development of subspecies differentiation of C.suppressalis.In this study we compared the differences of emergence time of the overwintering generation and analyzed the differences of correlation of fecundity and body size between different host races.The main results were showed as follows:1.Comparison of emergence time of overwintering generation between two host races of C.suppressalisIn order to clarify the emergence time of rice race and water-oat race of C.suppressalis we have observed the occurrence time of C.suppressalis adult.The results showed that(1)under indoor conditions,50% of the water-oat race pupated after 30 days,while the rice race pupation time was 46 days,the difference was 16 days.Under the natural field conditions,the difference was 17 days.(2)Under the natural field conditions,there were two eclosion peaks in both races.The second peak of water-oat race overlapped with the first peak of the rice race,the time of water-oat race to get 50% cumulative pupa rates 16 days earlier than that of the rice race.There are significant differences in the pupation time and eclosion time between the two host races of C.suppressalis.2.Comparison of correlation of fecundity and body size between two host races of the C.suppressalis.In order to clarify the correlation between fecundity and body size of two host races of the C.suppressalis,we measured the fecundity,body size and lifespan of adult.The results show that under the field condition,the data of body size(forewings length,head width and body length)and total egg production of the female adult in the rice field was significantly smaller than that of the female adult in the water-oat field(P<0.01).The life span of rice race was significantly longer than that of water-oat race(t=4.067,P<0.01).While under the indoor condition,the data of body size and total egg production of the female adult of rice race was smaller than that of the oat race(P<0.01),and the lifespan of female adult in this two host races shows no significant differences(t=-0.222,P = 0.825).Through the analysis of the correlation between the fecundity and the adults' size of the rice race and water-oat race,the results showed that: In the field,there was a significant correlation between the fecundity and the adults' size of rice race.When rearing C.suppressalis in the laboratory,there shows no significant correlation between the fecundity and the adult body size.We take the correlation between the fecundity and the adults' size as the race characteristic.The correlation analysis showed that there was a significant difference in this race characteristic between two host races under field conditions.While no significance was found in the indoor races.The results of this study show that there was a significant difference in the emergence time of overwintering generation between two host races of C.suppressalis.This is one of the direct evidence of seasonal different emergence time in different host race C.suppressalis.We take the correlation between the fecundity and the adults' size as the race characteristic.Differences in race characteristics between rice and water-oat races are important evidence for the subspecies different isolation of C.suppressalis.These results provided new method to understand the reason of sympatric speciation.
Keywords/Search Tags:Chilo suppressalis, host race, body size, egg production, overwintering generation, pupation
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