The Role of Abiotic Environmental Conditions and Herbivory in Shaping Bacterial Community Composition in Floral Nectar

Abstract

Identifying the processes that drive community assembly has long been a central theme in ecology. For microorganisms, a traditional prevailing hypothesis states that “everything is everywhere, but the environment selects”. Although the bacterial community in floral nectar may be affected by both atmosphere (air-borne bacteria) and animals as dispersal vectors, the environmental and geographic factors that shape microbial communities in floral nectar are unknown. We studied culturable bacterial communities in Asphodelus aestivus floral nectar and in its typical herbivorous bug Capsodes infuscatus, along an aridity gradient. Bacteria were sampled from floral nectar and bugs at four sites, spanning a geographical range of 200 km from Mediterranean to semi-arid conditions, under open and bagged flower treatments. In agreement with the niche assembly hypothesis, the differences in bacterial community compositions were explained by differences in abiotic environmental conditions. These results suggest that microbial model systems are useful for addressing macro-ecological questions. In addition, similar bacterial communities were found in the nectar and on the surface of the bugs that were documented visiting the flowers. These similarities imply that floral nectar bacteria dispersal is shaped not only by air borne bacteria and nectar consumers as previously reported, but also by visiting vectors like the mirid bugs.

Legitimate visitors and nectar robbers of Aquilegia formosa have different effects on nectar bacterial communities

“…), and Leuconostoc (Álvarez‐Pérez and Herrera , Samuni‐Blank et al. ). Others belong to families that have been isolated from floral tissue, including Enterobacteriaceae (Jacquemyn et al.…”

Linked networks reveal dual roles of insect dispersal and species sorting for bacterial communities in flowers

“…Unlike other systems where bacterial dispersal is difficult or near impossible to track, our flower visitor -plant -floral bacteria system allowed us to construct a detailed network of potential microbial vectors to plant hosts. Previous studies have used visitor guilds or observed single plant species to link visitor composition to variation in microbial community structure , Samuni-Blank et al 2014) but this study offers detailed species-level identification of floral visitors including predators and parasitoids across a relatively diverse coflowering plant community. This rich dataset allowed us to examine the relative contribution of each taxonomic guild of floral visitors.…”

“…However, poor vectors of pollen could be just as effective in vectoring microbes as pollinators. Previous work has shown that herbivores (Samuni-Blank et al 2014) and nectar robbers (Zemenick et al 2018) have distinct effects on microbial community composition. In the current study, a strong correlation between non-bee Hymenoptera and floral bacterial communities (Fig.…”

Izhakiella capsodis gen. nov., sp. nov., in the family Enterobacteriaceae, isolated from the mirid bug Capsodes infuscatus

“…T , N8PO1 and N8PI1 were isolated from the mirid bug Capsodes infuscatus during the course of a study on bacterial communities in floral nectar of Asphodelus aestivus plants (Samuni-Blank et al, 2014). Capsodes infuscatus bugs (Hemiptera: Miridae) deposit eggs inside the inflorescence stalk of its host (Asphodelus aestivus).…”