Host plant species determines symbiotic bacterial community mediating suppression of plant defenses

Abstract

Herbivore associated bacteria are vital mediators of plant and insect interactions. Host plants play an important role in shaping the gut bacterial community of insects. Colorado potato beetles (CPB; Leptinotarsa decemlineata) use several Solanum plants as hosts in their natural environment. We previously showed that symbiotic gut bacteria from CPB larvae suppressed jasmonate (JA)-induced defenses in tomato. However, little is known about how changes in the bacterial community may be involved in the manipulation of induced defenses in wild and cultivated Solanum plants of CPB. Here, we examined suppression of JA-mediated defense in wild and cultivated hosts of CPB by chemical elicitors and their symbiotic bacteria. Furthermore, we investigated associations between the gut bacterial community and suppression of plant defenses using 16 S rRNA amplicon sequencing. Symbiotic bacteria decreased plant defenses in all Solanum hosts and there were different gut bacterial communities in CPB fed on different host plants. When larvae were reared on different hosts, defense suppression differed among host plants. These results demonstrate that host plants influence herbivore gut bacterial communities and consequently affect the herbivore’s ability to manipulate JA-mediated plant defenses. Thus, the presence of symbiotic bacteria that suppress plant defenses might help CPB adapt to host plants.

A change in the bacterial community of spider mites decreases fecundity on multiple host plants

“…A couple of different scenarios might explain how these endosymbionts can influence spider mite performance on different host plant species. Herbivore‐associated microbes can positively and negatively influence insect fitness by mediating plant defenses and detoxifying phytochemicals (Chung et al, ) or enzymes, such as hydrolases, glucosidases, phosphatases, and glutathione transferases (Dowd & Shen, ; Shen & Dowd, ). For instance, the presence/absence of the bacterial endosymbionts Wolbachia , Cardinium, or/and Spiroplasma in the spider mite T. urticae has also been previously reported as altering distinct plant defense parameters and affecting mite performance, but there were no indications of a causal link between the two (Staudacher et al, ).…”

“…In this study, the host plants tested strongly altered the composition of the microbial community (diversity and abundance) in spider mites. Similarly, research on Colorado potato beetles (Chung et al, 2017), whiteflies (Su et al, 2016), aphids (Guidolin & Cônsoli, 2016), and pine processionary moths (Strano et al, 2017) have shown that populations that fed on different plant species had differing microbial communities. Here, we found that spider mites that were switched from bean to other host plants experienced changes in bacterial community diversity and species richness, especially for the main bacterial species.…”

“…For example, in polyphagous or oligophagous aphids, including Aphis gossypii (Jones, Bressan, Greenwell, & Fierer, ), Aphis citrcidus (Guidolin & Cônsoli, ), Aphis fabae (Chandler et al, ), and Acyrthosiphon pisum (Tsuchida, Koga, Shibao, Matsumoto, & Fukatsu, ), both primary and secondary symbionts are affected by the plant type on which the aphids feed. Host plants shape the diversity and abundance of larval gut symbiotic bacteria of the Colorado potato beetle, Leptinotarsa decemlineata , and thus affect the insect's ability to manipulate plant defenses in Solanum hosts (Chung et al, ). Similarly, antibiotic treatment can also alter the bacterial communities of herbivores (Lehman, Lundgren, & Petzke, ; Zouache, Voronin, Tran‐Van, & Mavingui, ); in particular, antibiotic treatment significantly influences the relative abundance of Wolbachia , Spiroplasma, and/or Cardinium in the spider mite Tetranychus urticae (Staudacher et al, ).…”

A response to Pennisi - “How do gut microbiomes help herbivores”, a hint into next-generation biocontrol solutions

“…Furthermore, we know that numerous plant defence compounds, such as monoterpenes, diterpenes, phenolics and alkaloids can be metabolized by bacteria (Malecky et al 2012, Marmulla and Harder 2014, Hammer and Bowers 2015, Vilanova et al 2016, and crucially, some invasive insects seem able to tolerate (Piskorski et al 2011) and even benefit (Lefort et al 2015) from such compounds. The presence of gut microbial communities capable of metabolising plant defence compounds (Chung et al 2017) could explain why some phytophagous insects are invasive whilst others are not. Several studies have already clearly stressed the central role of insect gut microbiome in overcoming the plant toxin barriers to facilitate insect host shifts (e.g.…”

Gut commensal bacteria in biological invasions

“…For example, Lymantria dispar Linnaeus, 1758, a notorious invasive pest in North America, was shown to possess abundant gut bacteria that may help the host insect detoxify plant defensive chemicals (Tobin et al 2012;Mason & Raffa 2014;Mason et al 2015). A range of other invasive insects from other orders, such as Anoplophora glabripennis (Motschulsky, 1854), D. valens, Rhynchophorus ferrugineus (Olivier, 1791), Leptinotarsa decemlineata (Say, 1824), Ceratitis capitata (Wiedemann, 1824) and Bactrocera dorsalis (Hendel, 1912), have been documented to have abundant gut bacterial communities (Schloss et al 2006;Ben-Yosef et al 2008;Geib et al 2009;Xu et al 2015;Yao et al 2016;Chung et al 2017).…”