Effects Of Temperature On Two Drosophila Species And Their Transmitted Grape Sour Rot Disease

Grape sour rot disease is one of the major diseases in the vineyard.Fruit flies are some indispensable vector for the occurrence of grape sour rot disease.This project will focus on the research of an important invasive pest,D.suzukii,because it has resulted in serious harm to the fruit farming industry and economy in the invaded countries.Therefore,it is very essential to predict the potential geographical distribution of D.suzukii for making effective control strategies.The geographical distribution of organisms is determined by their tolerance to local environmental conditions(such as thermal tolerance)and their interactions with another species.Now,the research on thermal tolerance of D.suzukii mainly focus on cold tolerance,but little is known about heat tolerance.Moreover,studies on the interspecific relationship between the invasive species D.suzukii and the native species D.melanogaster have not been extensively carried out.In addition,whether the invasion of D.suzukii will affect the occurrence of grape sour rot disease is still unknown.The rise of global average temperature resulted from climate change has a significant impact on the organisms on the earth.Thus,based on these scientific questions,we studied the plastic response of adults of D.suzukii to heat stress,the interspecific relationship between D.suzukii and D.melanogaster,and the impact of invasion of D.suzukii on the occurrence of grape sour rot disease.The main results are as follows:1 The basal and plastic heat tolerance of D.suzukii adults in different mating status were determined.Adults of D.suzukii have limited basal heat tolerance(less than 36~oC)and its plasticity(maximum about1.5~oC).In addition,we found that those mated females have higher basal heat tolerance than virgin females,but mated males have lower basal heat tolerance than virgin males,and the thermal acclimation ability of virgin adults was generally higher than that of mated adults.2 The interspecific relationship between D.melanogaster and D.suzukii was determined.For D.melanogaster,the presence of D.suzukii benefits the increase in number of offspring adults.However,as to D.suzukii,the presence of D.melanogaster inhibit the increase in number of offspring adults.Moreover,this specific interspecific relationship is not altered by temperature(23~oC,26~oC,29~oC)and host(sound and rotten grapes).In addition,we also found D.suzukii preferred to lay eggs on fresh and sound grapes,while D.melanogaster preferred to lay eggs on rotten grapes.3 The occurrence of grape sour rot disease caused by different fruit flies was determined.The presence of fruit flies can promote the outbreak of grape sour rot disease.The grape sour rot disease is gradually becoming serious on different treatments of drosophila species,no drosophila species,D.suzukii,D.melanogaster,mixed population of D.suzukii and D.melanogaster.Moreover,according to the total bacterial colonies in 1 ml of grape juice,there were significant differences in the number of bacterial colonies that transmitted by different drosophila species,D.melanogaster(9.99±0.06),mixed population of D.melanogaster and D.suzukii(9.95±0.06),D.suzukii(9.62±0.24)and no drosophila species(9.45±0.28).The amount of bacteria transmitted by drosophila species are significantly different at different temperatures,29~oC(9.82±0.21),26~oC(9.80±0.31)and 23~oC(9.64±0.33).In addition,in the absence of no drosophila species,pre-inoculation of pathogens on grapes would promote the occurrence of spur rot disease,but in the preference of any drosophila species,such as D.suzukii and D.melanogaster,pre-inoculation of pathogens on grapes has no significant impact on the occurrence of spur rot disease.The temperature increase could contribute to the occurrence of grape sour rot disease,but the difference is not significant.