Identification of the core symbiotic bacteria of Laodelphax striatellus

Abstract:

The core symbiotic bacteria of insect vectors have the potential to be used as genetically engineered bacteria to control arboviruses. Laodelphax striatellus is an important agricultural pest and also the transmission vector of rice stripe virus, the causative agent of rice stripe disease that occurred with dramatic yield reduction or even no harvest.[Objective] In this study, the bacterial communities of L. striatellus were sequenced through 16S rDNA next-generation sequencing methods, and the core symbiotic bacteria were identified.[Methods] From 2018 to 2020, L. striatellus have been collected from the rice fields in Kunming of Yunnan Province, and in Kaifeng and Fanxian of Henan province, as well as in the greenhouse, in which microbiomes were sequenced and analyzed.[Results] All 37 L. striatellus sequencing samples carry both intracellular and extracellular bacteria. In the genus level, the intracellular bacteria Wolbachia exhibited the highest average relative abundance of 51.96%. Its representative OTU (OTU45) accounts for 96.55% of the total number of 85 OTUs and exists in all sequenced insect samples. Except for Wolbachia, all the other common core bacteria were extracellular, in which the four core genera with high abundances were Acinetobacter, Pantoea, Enterobacter and Pseudomonas, with average relative abundances of 0.25%-2.97% in all ten common core genera. There are dominant bacteria in insect samples from different rice fields. High-abundant Rickettsia were found in Kunming samples, both Arsonophonus and Cardinium were identified in Fanxian samples, and Acetobacter, Sulcia and Pantoea were found in Kaifeng samples. These rice-field dominant bacteria include a variety of intracellular bacteria. When the rice-field insects were fed with sucrose for 24 h in the greenhouse, the relative abundance of Wolbachia increased significantly and the microbial composition became closer to that of the greenhouse. Within the offsprings of these rice-field insects, the intracellular bacteria, except for Wolbachia, lost or existed in a few samples with low level.[Conclusion] This study preliminarily clarified the symbiotic bacterial composition of L. striatellus, identified common core bacteria and identified dominant symbiotic bacteria in the three Chinese rice areas, providing engineered bacteria for antiviral research through insect vector's core bacteria.