Combining sterile and incompatible insect techniques for the population suppression of Drosophila suzukii

International audienceThe spotted wing Drosophila, Drosophila suzukii, has recently invaded Europe and the Americas, and it is a major threat for a wide variety of commercial soft fruits both in open field and greenhouse production systems. D. suzukii infests a wide range of ripening fruits, leading to substantial yield and revenue losses. As the application of insecticides close to the harvest period poses great concerns, the development of an efficient environment-friendly control approach to fight D. suzukii is necessary. In this study, we exploited the sterile insect technique (SIT) in combination with Wolbachia symbiosis as a population suppression approach that can constitute a potential component of an area-wide integrated pest management program. We aimed to establish a combined SIT/incompatible insect technique (IIT) protocol that would require lower irradiation doses as a complementary tool for D. suzukii management. Two D. suzukii lines trans-infected with the Wolbachia wHa and wTei strains were irradiated at doses four times less than usual (e.g., 45 Gy), and the egg hatching and adult emergence were determined. Our results indicated that wHa and wTei females as well as wHa males were sterile at this low dose. The longevity, adult emergence and flight ability of adults were evaluated, and no major effect caused by irradiation was detected. Our data indicate that a SIT/IIT protocol can be a competent approach for D. suzukii management

Functional characterization of TtgABC efflux pump of the RND family in the entomopathogenic bacterium Pseudomonas entomophila

Pseudomonas entomophila is a recently characterized entomopathogenic bacterium that can infect and kill Drosophila melanogaster upon ingestion. Although it is an environmental strain, it exhibits intrinsic resistance towards several antibiotics, as demonstrated in the present study. The intrinsic antibiotic resistance of P. entomophila was tested for ampicillin, chloramphenicol, kanamycin, streptomycine, tetracycline, imipenem, and ethidium bromide. Minimum inhibitory concentrations (MICs) were 1000 μg/ml for ampicillin, 150 μg/ml for chloramphenicol, 100 μg/ml for streptomycin, and >2000 μg/ml for ethidium bromide. The MIC values for kanamycin, tetracycline, and imipenem were much lower (5, 4, and <1 μg/ml respectively). Genome mining of the P. entomophila genome identified genes belonging to the resistance-nodulation-division (RND) family which encode efflux pumps. The ttgABC operon encoding an RND-type efflux pump in the P. entomophila genome was disrupted and its implication in ampicillin, chloramphenicol, streptomycin and ethidium bormide resistance was confirmed. © 2015, Springer-Verlag Berlin Heidelberg and the University of Milan

Prokaryotic diversity in biodeteriorated wood coming from the Bükkábrány fossil forest

The oldest standing paleo-forest in the world is located at Bükkábrány in Hungary. Some 7 million years ago a sudden and rapid deposition of sands from a prograding delta resulted in rise of the level of Lake Pannon that covered the landscape. The flood created an anoxic burial environment which preserved unmineralised tree trunks to the present day. Examination of wood sample coming from these trunks using light and scanning electron microscopy revealed extended wood biodeterioration. Culture-independent molecular methods were used to study prokaryotic diversity present in biodeteriorated wood. Phylogenetic analysis of 16S gene clone libraries and 454 pyrosequencing analysis revealed the presence of prokaryotes, including methylotrophic bacteria and bacteria that could be members of the indigenous microbiota found inside the trunk. The rest of identified bacteria are commonly isolated from freshwater habitats possibly reflecting the shift of bacterial biota that occurred in the wood and its close environment after the rise of Lake Pannon. Moreover Archaea were detected in biodeteriorated wood for the first time. The detection of Archaea raises for the first time the question of their possible implication in wood biodeterioration as well as their possible interactions with bacterial communities that colonize wood. © 2015 Elsevier Ltd

Microbial diversity in biodeteriorated Greek historical documents dating back to the 19th and 20th century: A case study

Paper documents in archives, libraries, and museums often undergo biodeterioration by microorganisms. Fungi and less often bacteria have been described to advance paper staining, so called “foxing” and degradation of paper substrates. In this study, for the first time, the fungal and bacterial diversity in biodeteriorated paper documents of Hellenic General State Archives dating back to the 19th and 20th century has been assessed by culture-dependent and independent methods. The internally transcribed spacer (ITS) region and 16S rRNA gene were amplified by PCR from fungal and bacterial isolates and amplicons were sequenced. Sequence analysis and phylogeny revealed fungal phylotypes like Penicillium sp., Cladosporium sp., Penicillium citrinum, Alternaria infectoria, Alternaria alternata, Epicoccum nigrum, and Penicillium chrysogenum which are often implicated in paper deterioration. Bacterial phylotypes closely related to known biodeteriogenic bacteria such as Bacillus spp., Micrococcus spp., Kocuria sp. in accordance with previous studies were characterized. Among the fungal phylotypes described in this study are included well-known allergens such as Penicillium spp., Alternaria spp., and Cladosporium spp. that impose a serious health threat on staff members and scholars. Furthermore, fungal isolates such as Chalastospora gossypii and Trametes ochracea have been identified and implicated in biodeterioration of historical paper manuscripts in this study for the first time. Certain new or less known fungi and bacteria implicated in paper degradation were retrieved, indicating that particular ambient conditions, substrate chemistry, or even location might influence the composition of colonizing microbiota. © 2018 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd

White pupae phenotype of tephritids is caused by parallel mutations of a MFS transporter

Mass releases of sterilized male insects, in the frame of sterile insect technique programs, have helped suppress insect pest populations since the 1950s. In the major horticultural pests Bactrocera dorsalis, Ceratitis capitata, and Zeugodacus cucurbitae, a key phenotype white pupae (wp) has been used for decades to selectively remove females before releases, yet the gene responsible remained unknown. Here, we use classical and modern genetic approaches to identify and functionally characterize causal wp- mutations in these distantly related fruit fly species. We find that the wp phenotype is produced by parallel mutations in a single, conserved gene. CRISPR/Cas9-mediated knockout of the wp gene leads to the rapid generation of white pupae strains in C. capitata and B. tryoni. The conserved phenotype and independent nature of wp- mutations suggest this technique can provide a generic approach to produce sexing strains in other major medical and agricultural insect pests

Mutant <em>KRAS </em>promotes malignant pleural effusion formation.

Malignant pleural effusion (MPE) is the lethal consequence of various human cancers metastatic to the pleural cavity. However, the mechanisms responsible for the development of MPE are still obscure. Here we show that mutant KRAS is important for MPE induction in mice. Pleural disseminated, mutant KRAS bearing tumour cells upregulate and systemically release chemokine ligand 2 (CCL2) into the bloodstream to mobilize myeloid cells from the host bone marrow to the pleural space via the spleen. These cells promote MPE formation, as indicated by splenectomy and splenocyte restoration experiments. In addition, KRAS mutations are frequently detected in human MPE and cell lines isolated thereof, but are often lost during automated analyses, as indicated by manual versus automated examination of Sanger sequencing traces. Finally, the novel KRAS inhibitor deltarasin and a monoclonal antibody directed against CCL2 are equally effective against an experimental mouse model of MPE, a result that holds promise for future efficient therapies against the human condition

Mutant KRAS promotes malignant pleural effusion formation

Malignant pleural effusion (MPE) is the lethal consequence of various human cancers metastatic to the pleural cavity. However, the mechanisms responsible for the development of MPE are still obscure. Here we show that mutant KRAS is important for MPE induction in mice. Pleural disseminated, mutant KRAS bearing tumour cells upregulate and systemically release chemokine ligand 2 (CCL2) into the bloodstream to mobilize myeloid cells from the host bone marrow to the pleural space via the spleen. These cells promote MPE formation, as indicated by splenectomy and splenocyte restoration experiments. In addition, KRAS mutations are frequently detected in human MPE and cell lines isolated thereof, but are often lost during automated analyses, as indicated by manual versus automated examination of Sanger sequencing traces. Finally, the novel KRAS inhibitor deltarasin and a monoclonal antibody directed against CCL2 are equally effective against an experimental mouse model of MPE, a result that holds promise for future efficient therapies against the human condition

Functional characterization of TtgABC efflux pump of the RND family in the entomopathogenic bacterium Pseudomonas entomophila

Pseudomonas entomophila is a recently characterized entomopathogenic bacterium that can infect and kill Drosophila melanogaster upon ingestion. Although it is an environmental strain, it exhibits intrinsic resistance towards several antibiotics, as demonstrated in the present study. The intrinsic antibiotic resistance of P. entomophila was tested for ampicillin, chloramphenicol, kanamycin, streptomycine, tetracycline, imipenem, and ethidium bromide. Minimum inhibitory concentrations (MICs) were 1000 μg/ml for ampicillin, 150 μg/ml for chloramphenicol, 100 μg/ml for streptomycin, and >2000 μg/ml for ethidium bromide. The MIC values for kanamycin, tetracycline, and imipenem were much lower (5, 4, and <1 μg/ml respectively). Genome mining of the P. entomophila genome identified genes belonging to the resistance-nodulation-division (RND) family which encode efflux pumps. The ttgABC operon encoding an RND-type efflux pump in the P. entomophila genome was disrupted and its implication in ampicillin, chloramphenicol, streptomycin and ethidium bormide resistance was confirmed. © 2015 Springer-Verlag Berlin Heidelberg and the University of Mila