The structure of the cereal leaf beetle (Oulema melanopus) microbiome depends on the insect’s developmental stage, host plant, and origin

Abstract

Cereal leaf beetle (CLB, Oulema melanopus, Coleoptera, Chrysomelidae) is a serious agricultural pest that causes considerable damages to agricultural production. The aim of this study was to characterize the bacterial communities associated with larvae and imagoes of CLB collected from various cereal host species and locations. The bacterial profile was characterized by 16S rRNA gene sequencing at the V3-V4 hypervariable region. Using taxonomy-based analysis, the bacterial community of CLB containing 16 phyla, 26 classes, 49 orders, 78 families, 94 genera, and 63 species of bacteria was identified. The abundance of Wolbachia, Rickettsia, and Lactococcus genus was significantly higher in CLB imagoes than in larvae. Statistical analysis confirmed that the bacterial community of the larvae is more diverse in comparison to imagoes and that insects collected from spring barley and wheat are characterized by a much higher biodiversity level of bacterial genera and species than insects collected from other cereals. Obtained results indicated that the developmental stage, the host plant, and the insect’s sampling location affected the CLB’s microbiome. Additionally, the CLB core microbiome was determined. It consists of 2 genera (Wolbachia and Rickettsia) shared by at least 90% tested CLB insects, regardless of the variables analysed.

Does Leptinotarsa decemlineata larval survival after pesticide treatment depend on microbiome composition?

“…The manipulative experiment showed that larvae fed with L. lactis before chlorpyrifos treatment had a five‐fold lower mortality rate. Lactococcus lactis is a member of the lactic acid bacteria that are commonly associated with the microbiomes of insects, 66 contributing to the digestion of polysaccharides and sucrose 61,67–69 . This provides two possible explanations for our findings: (i) L. lactis degraded chlorpyrifos or (ii) it provided nutrients to the host to overcome pesticide stress.…”

The Impact of Oulema melanopus—Associated Bacteria on the Wheat Defense Response to the Feeding of Their Insect Hosts

“…Chung et al [ 16 ] have indicated that Wolbachia may play a key role in shaping the tomato plant’s defensive response to CPB feeding. We have previously indicated that at least 90% of the CLB populations tested are associated with Wolbachia and Rickettsia [ 12 ], which may suggest that the above-mentioned genera of bacteria may have a significant impact not only on the insect host but also on the plant defense response. Therefore, the main aim of this study was to check how the bacteria associated with the CLB larvae modulated the wheat’s response upon larvae feeding.…”

“…Generally, herbivorous insects are associated with a wide variety of microorganisms, including bacteria. The CLB is known to be associated with a whole range of bacteria (such as those belonging to the Acinetobacter , Stenotrophomonas , Streptococcus , Serratia , Moraxella , Lactobacillus , Pseudomonas , and Pantoea genus), and their composition can be influenced by various factors, including diet [ 12 ]. However, regardless of the variables analysed (developmental stage, cereal host species and locations from which insects were collected), at least 90% of the tested CLB insects were associated with bacteria belonging to the genera Wolbachia and Rickettsia [ 12 ].…”

Insect Gut Bacteria Promoting the Growth of Tomato Plants (Solanum lycopersicum L.)

“…The NGS analysis of plant DNA was performed to assess if the microbiome composition of bacteria-treated plants differs from the microbiome of the control group treated with water. We used the methodology previously described [ 21 ]. The plant DNA extraction process was verified against the presence of 16S rDNA using bacterial universal primers [ 66 ], and against the presence of commonly reported [ 67 ] contaminations in NGS projects (e.g., with Cutibacterium acnes ) using the nested-PCR technique [ 68 ].…”

“…Bacteria-insect relationships are complex and among positive interactions involve both commensalism and mutualism [ 18 ]. The internal diversity of the insect microbiome is related to a variety of gut structures and compartments, various pH levels, redox potential, digestive enzymes [ 19 , 20 ], and insect food [ 21 ]. The studies show that there is a relationship between gut structure and variation of the microbiome.…”