| Frankliniella occidentalis(Perganda)is an important invasive pest.It has the characteristics of small size,high fecundity,short generation,strong concealment,and omnivorous,which make F.occidentalis colonize in various areas and outbreak rapidly.It can directly damage by feeding and oviposition,causing shrinkage of leaves,fading of petals and scarring of fruit.It also indirectly spread various viruses such as Tomato spotted wilt virus(TSWV)and Impatiens necrotic spot virus(INSV),It has caused serious damage to vegetables,flowers and crops all over the world.The serious damage of F.occidentalis is related to its omnivorous characteristics of feeding pollen nectar in addition to plants.Pollen nectar can significantly promote the population growth.Does F.occidentalis feeding on different foods have the same gut bacteria.Based on 16 S rDNA library technology and Illumina MiSeq sequencing technology,the gut bacterial diversity of F.occidentalis feeding on Chinese rose,kidney bean pod and kidney bean leaf was analyzed.The effect of antibiotic treatment on the removal of gut bacteria was studied.And the effect of removal of gut bacteria on the growth,development and reproduction of F.occidentalis was studied too.The results will provide a theoretical basis for understanding the gut bacterial function in F.occidentalis and a new idea for the prevention and control on F.occidentalis,the main results were as follows: 1.Diversity were compared of gut bacteria in F.occidentalis after feeding on different foodsIn order to determine the composition and diversity of intestinal bacteria in thrips feeding Chinese rose(FF),kidney bean pod(PF)and kidney bean leaf(LF),the 16 S rDNA(V3+V4)variable region was sequenced on Illumina Miseq platform.The results showed that through OTUs annotation on each classified order,F.occidentalis feeding on Chinese rose(FF)had the highest number of gut bacterial annotation,there were 17 phyla,41 classes,66 orders,87 families and 89 genera.followed by F.occidentalis feeding on bean leaf(LF),and feeding on bean pod(PF).The diversity analysis of gut bacterial populations of F.occidentalis feeding on three different foods showed that the Chao and Ace indexes of PF were the highest,which were 1569.40 and 1609.27 respectively,indicating the highest bacterial abundance in PF.In FF,the Simpson index was 0.96,PF was 0.82 and LF was 0.77,respectively,from which it could be known that the FF diversity of feeding Chinese rose was the highest.The dominant bacteria of F.occidentalis that feed on three different foods at the phylum level was Proteobacteria,and the relative abundancewas 84.08% in FF,95.58% in PF and 95.33% in LF,respectively.The secondary dominant bacteria were Actinobacteria,and the relative abundance was 3.63% in FF,3.04% in PF and 2.42% in LF,respectively.At the level of dominant bacteria in genus,the dominant one was Stenotrophomonas in PF and LF.In FF the dominant one was Rosenbergiella,and secondary dominat one was Pantoea.The KEGG pathway annotation predicted that the gut bacterial gene function of F.occidentalis was involved in carbohydrate metabolism and amino acid metabolism.2.The effect of three antibiotics on the survival of F.occidentalis and culturable gut bacteriaTo explore the effect of different antibiotics on F.occidentalis,Ampicillin(AMP),chloramphenicol(CAP)and streptomycin sulphate(SM)were used to treat F.occidentalis by membrane feeding and leaf dipping methods respectively.The influences of three kinds of antibiotics on the mortality and the removal effects on the culturable gut bacteria in F.occidentalis were determined.The results showed that the antibiotics had significant effect on the mortality of F.occidentali,and the mortality increased with the increase of concentration and extension of time.The mortality was biggest under the concentration of 50.00 mg/m L of all 3 antibiotics at 72 h at both methods.The membrane feeding method had stronger effect than leaf dipping method.25.00 mg/mL ampicillin and 50.00 mg/m L streptomycin sulfate had best remove effects on culturable bacteria in the gut of F.occidentalis under the two methods.The concentration of chloramphenicol with 50.00 mg/m L at 24 h had biggest remove effect at the membrane feeding method,while it hadn't the effect at leaf dipping method.The results indicated that the effect of antibiotics on the mortality of F.occidentalis and the removal effect were positively correlated with antibiotic type,concentration and treatment time,it also had the relative with treatment method.3.Effects of gut bacteria on the growth and development of F.occidentalisTo determine the effect of gut bacteria on the growth,development and reproduction on F.occidentalis.Ampicillin(25 mg/mL)was used to treat F.occidentalis,and the effects were evaluated after removing gut bacteria.The results showed that the development time of first instar nymphs and pre-pupae were shorter than that of the control group after treatment with 25 mg/m L ampicillin,and the development time of second instar nymph was 0.71 day longer than that of the control group.Ampicillin also resulted in a 1.15-day advance in oviposition of F.occidentalis,extending the life longevity of female adults and decreased oviposition by 25.53 compared to the control group.The results indicated that the gut bacteria in F.occidentalis had the effect on the development of some stages,but not on immature period.The gut bacteria had an important promoting effect on the reproduction of F.occidentalis. |
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