Characterization of Burkholderia bacteria clade compositions in soil and Riptortus pedestris (Hemiptera: Alydidae) in South Korea

Abstract

Riptortus pedestris (Hemiptera: Alydidae) is known to acquire the genus Burkholderia, symbiotic bacteria, from soil. Therefore, symbiont acquisition of R. pedestris would be directly affected by bacterial diversity in soil. Soil typically harbors diverse microbes including different Burkholderia clades such as SBE (stinkbug-associated beneficial and environmental), PBE (plant-associated beneficial and environmental), and BCC (Burkholderia cepacia and complex). Nevertheless, little is known about Burkholderia acquisition patterns of R. pedestris in nature, especially in the context of bacteria clade compositions in soil. Therefore, based on diagnostic PCR analysis, we investigated Burkholderia clade compositions in field-collected soil itself and R. pedestris when the insects were provided with the soil. Also, wild R. pedestris were surveyed to characterize their Burkholderia compositions. First, 88.44% of soil samples were detected with the genus Burkholderia, and triple clade (SBE + PBE + BCC) was most frequently detected. Second, R. pedestris nymphs readily acquired Burkholderia bacteria from field-collected soil where 91.25% of the reared insects harbored the bacteria in their midguts. In contrast to soil, the detection of single BCC clade was the most dominant among the three identified Burkholderia clades. Third, from wild R. pedestris, 80.62% of the insects were found to harbor the genus Burkholderia, and single BCC clade was most frequently detected. Finally, 29.13% and 47.06% of the reared and wild R. pedestris were detected with unidentified Burkholderia clade, which does not belong to any of the three identified clades. Our findings provide baseline information to better understand ecological associations between R. pedestris and Burkholderia bacteria in different clades.