| The Asian citrus psyllid,Diaphorina citri Kuwayama,is a vector for the bacterium that spreads citrus huanglongbing,which has a serious impact on the citrus industry.At present,the control of Asian citrus psyllid mainly relies on chemical control,insecticides,but the frequent use of insecticides increases the resistance of Asian citrus psyllid and seriously pollutes the environment.It is urgent to develop a new biological control technology for Asian citrus psyllid population.It is known that endosymbionts can affect the biological characteristics of insect hosts in many aspects,such as reproduction and body color.And it has been reported that there are differences in flight ability and insecticide sensitivity of Asian citrus psyllid with different body colors.However,the intrinsic relationship among reproduction and development,endosymbionts and body color has not yet been reported.Therefore,we measured the parameters of the reproduction and development of three color morphs(blue/green,gray/brown,orange/yellow),firstly.And then 16 S rDNA sequencing was used to comparatively quantify the endosymbionts of the three color morphs.In this way can we explore the relationship between color polymorphisms and the diversity of endosymbionts in color morphs,and thus,provide a theoretical basis for developing new bioagents for the control of this insect.We obtained eight main results.(1)The sex ratio and quantity of Asian citrus psyllid with different body colors were compared.The results showed that there was no significant difference in the number of male and female.In addition,there was no significant difference in the number of female and male adults,indicating that the female to male ratio of Asian citrus psyllid was close to 1:1 under laboratory conditions.Moreover,we compared the total numbers of individuals in the color morph groups to find out that there were significant differences(p < 0.001),and the orange/yellow morph was the least abundant.(2)The developmental and reproductive parameters of Asian citrus psyllid with different body colors were compared.We recorded the immature developmental time.The results showed that there were significant differences in the egg hatching period(p= 0.064),first instar,second instar,third instar,and fifth instar(p < 0.001).There was no significant difference in the development time of the fourth instar(p = 0.783).Except for the first and fourth instars,the early stage of the orange/yellow morph had the longest duration as compared to other life stages.Female and male adults from each color morph group were weighed on an analytical microbalance(sensitivity = 0.0001mg).It was observed that the weight of blue/green female adults was significantly different from that of the blue/green males(p = 0.014).It recorded the daily spawning quantity of color morphs and tested the difference.The number of eggs spawned by each mated female in the different color morph groups was not significantly different(p > 0.05).The results showed that the number of eggs laid per female was not affected by body color.We mated adults of the same color and found that the three color morph groups appeared in the F1 generation born from the mating of same-color Asian citrus psyllid.The blue/green morph was the most abundant,and the difference in number was significant.For the gray/brown group,there were significant differences in the F1 generation color morphs,where the gray/brown morph was the most abundant,and the difference in number was highly significant.However,for the orange/yellow morphs,no significant differences in the number of F1 generation color morphs were observed(p > 0.05).(3)We used 16 S rDNA sequencing technology was used to detect differences among endosymionts of three color morphs.The results showed that no significant differences were observed across the three color morph groups of Asian citrus psyllid in richness and diversity of endosymbionts(p > 0.05).However,by calculating the Beta-diversity,the results indicated that significant differences in the structure of endosymbiont communities in different color morphs,and the structures of endosymiont in the same color morphs were similar.In order to screen the strains that can be used as biomarkers to distinguish from three color morphs,we combined the linear discriminant analysis with the biomarker screening method of random forest model.It was eventually found there were two potential microbial biomarkers,Rhodobacteraceae and Pseudomonas.qPCR was used to verify the significantly different strains,and the contents of these two strains were significantly different among the three body colors of Asian citrus psyllid(p < 0.05).In order to determine the relationship between endosymbiontsa and the difference in three color forms,we predicted the functions of symbiotic bacteria in Asian psyllid citrus with different body colors.Results showed that there were three significant differences which related to the survival of Asian psyllid citrus: D-Glutamine and Dglutamate metabolism,porphyrin and chlorophyll metabolism,and biosynthesis of unsaturated fatty acids.Fatty acids are one of the important components of fat body of insects.Previous studies had shown that there were differences in body mass and biosynthesis of unsaturated fatty acids predicted by endosymbionts of three color morphs.Nevertheless,it was precisely because of extraction and detection of unsaturated fatty acids in the different color morphs that there was no significant difference in the content of unsaturated fatty acids of two genders(p > 0.05),and there was significant difference in the content of unsaturated fatty acids of different color morphs.At the same time,the unsaturated fatty acid content was the highest among orange/yellow male adults.In summary,this study selected two significantly different and abundant endosymbionts as potential biomarkers,Rhodobacteraceae and Pseudomonas.These two endosymbionts are related to the metabolism of Asian citrus psyllid,especially the metabolism of the unsaturated fatty acid,which,in turn,allows them to influence color polymorphism in Asian citrus psyllid.The highlighted endosymbiont species and specific color morphism may be key factors to consider in management decisions for control of the Asian citrus psyllid. |
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