| The scale insects in Coccidae are common forest pests,harm to numerous urban landscaping plants,nursery ornamental plants or economic forests.They stick on the surface of plants and suck the plant sap by using mouthpart.Most of the time,scale insects fix on their hosts and secret wax to protect themselves.Considering many kinds of nutrients that indispensable to scale insects are absent in plant sap,scale insects usually depend on symbiotic microorganisms which can provide those missing nutrients.However,the symbiotic microorganisms in Coccidae are less known and inconclusive.In this study,30 representative Coccidae species were choose,and high-throughput sequencing technology was used to detect the microorganism community in these Coccidae species.The 16 S rRNA gene and the ITS gene were amplified to distinguish bacterial and fungal species,respectively.Then,the dominant bacteria and fungus in Coccidae species were analyzed.The main results are listed below.1.In the high-throughput sequencing analysis of bacterial community,28 species among Coccidae were used,without Saissetia coffeae and Parasaissetia sp.species.22 species have high diversity of bacterial communities,and the community richness of each bacteria averaged is less than 20%.So,these 22 kinds of scale insects presumably don't have any symbiotic bacteria.Whereas in another 6 kinds of scale insects,they probably had facultative symbiotic bacteria that capable of inducing reproductive abnormalities in their host: Ceroplastes rubens,Ce.sp.,Pulvinaria aurantii and Milviscutulus sp.host Rickettsia,average community richness is 89.36%.Coccus praetermissus hosts Spiroplasma,community richness is 99.11%.Sa.oleae hosts Candidatus Cardinium,community richness is 43.71%.2.In the analysis of fungal community,each sample we used host the dominant fungus placed same within the entomoparasitic fungal genus Ophiocordyceps,average community richness is more than 80%.These dominant fungi possibly be the symbiotic microorganism for scale insects that take part in the nutrient metabolism of host.In addition,the molecular phylogenetic analysis of these Ophiocordyceps-allied fungi clearly indicated that Ophiocordyceps fungi in Coccidae species was divided into two branches: The Ophiocordyceps fungi in Ce.ceriferus,Ce.cirripediformis,Ce.floridensis,Ce.japonicus,Ce.kunmingensis,Ce.pseudoceriferus,Ce.rubens,Ce.rusci,Ce.sp.,Co.hesperidum,Co.praetermissus,Co.sp.,Pu.aurantii,Mi.pyriformis,Mi.sp.,Eucalymnatus tessellatus,Dicyphococcus ficicola,Di.sp.,Ericerus pela,Rhodococcus sariuoni,Takahashia japonica were in same branch Clade A with O.coccidiicola,a pathogenic fungi of scale insect.The Ophiocordyceps fungi in Sa.coffeae,Sa.miranda,Sa.oleae,Sa.sp.,Pa.sp.,Co.celatus,Co.viridis,Pu.psidii,Megapulvinaria maxima were in another branch Clade B,the pathogenic fungi of ant O.unilateralis was close this branch.The abvoe results show that the symbiotic microorganism has a dominant position in Coccidae is a kind of fungus.In summary,the primary symbiotic microorganism in Coccidae is different to a group of scale insects had studied.Not the symbiotic bacteria Flavobacteriia or ?-Proteobacteria,but the member of Ophiocordyceps fungi.This kind of symbiotic fungus is nonpathogenic and may be involved in host nutrient metabolism probably.The phylogenetic tree analysis consequence of the ITS gene of Ophiocordyceps reflected that two types of Ophiocordyceps fungi had been found and divided the Coccidae species.Maybe the dominant position of these symbiotic fungi suppressing the exist of symbiotic bacteria,so,only three kinds of secondary symbiotic bacteria had been found in a few of Coccidae speecies.A comprehensive survey of the bacterial community and fungal community of the representative insects in Coccidae had been studied and the dominant microorganism had been clarified in our study.This study provides new clues for the symbiotic microorganism in scale insects. |
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