Endosymbionts, Parasites, and Pathogens

Lopez RP, Díaz-Nieto LM, & Berón CM. 2016

Nuevo hospedador y distribución del parásito de mosquitos Strelkovimermis spiculatus [New host and distribution for the mosquito parasite Strelkovimermis spiculatus].

Revista de la Sociedad Entomologica Argentina 75, 101-104.

Strelkovimermis spiculatus Poinar & Camino 1986 (Nematoda: Mermithidae) was found parasitizing some mosquito genera as Aedes (Ochlerotatus), Culex and Psorophora. In a mosquito distribution project in Buenos Aires, Argentina, we found nematodes infecting mosquito larvae in natural breeding sites in the outskirts of Mar del Plata city. The aim of this work was to identify this parasite in this distribution area and determine the mosquito species host. COI and 18S rRNA-ITS1-5.8S rRNA-ITS2-28S rRNA gene fragments were described and were used for molecular identification of this nematode, confirming the morphological diagnostic traits. In this report, a new host of S. spiculatus, the mosquito larvae of Culex eduardoi was detected, expanding its southeastern distribution.

Flores GAM, Lopez RP, Cerrudo CS, Perotti MA, Consolo VF, & Berón CM. 2023

Wolbachia dominance influences the Culex quinquefasciatus microbiota.

Scientific Reports 13, 18980.

Microorganisms present in mosquitoes and their interactions are key factors affecting insect development. Among them, Wolbachia is closely associated with the host and affects several fitness parameters. In this study, the bacterial and fungal microbiota from two laboratory Culex quinquefasciatus isolines (wild type and tetracycline-cured) were characterized by metagenome amplicon sequencing of the ITS2 and 16S rRNA genes at different developmental stages and feeding conditions. We identified 572 bacterial and 61 fungal OTUs. Both isolines presented variable bacterial communities and different trends in the distribution of diversity among the groups. The lowest bacterial richness was detected in sugar-fed adults of the cured isoline, whereas fungal richness was highly reduced in blood-fed mosquitoes. Beta diversity analysis indicated that isolines are an important factor in the differentiation of mosquito bacterial communities. Considering composition, Penicillium was the dominant fungal genus, whereas Wolbachia dominance was inversely related to that of Enterobacteria (mainly Thorsellia and Serratia). This study provides a more complete overview of the mosquito microbiome, emphasizing specific highly abundant components that should be considered in microorganism manipulation approaches to control vector-borne diseases.

Díaz-Nieto LM, D'Alessio C, Perotti MA, & Berón CM. 2016

Culex pipiens development is greatly influenced by native bacteria and exogenous yeast.

PLoS ONE 11, e0153133.

Culex pipiens is the most cosmopolitan mosquito of the Pipiens Assemblage. By studying the nature of interactions between this species and microorganisms common to its breeding environment we can unravel important pitfalls encountered during development. We tested the survival rate of larval stages, pupae and adults of a Cx. pipiens colony exposed to a variety of microorganisms in laboratory conditions and assessed the transmission to offspring (F1) by those organisms that secured development up to adulthood. Three complementary experiments were designed to: 1) explore the nutritional value of yeasts and other microorganisms during Cx. pipiens development; 2) elucidate the transstadial transmission of yeast to the host offspring; and 3) to examine the relevance of all these microorganisms in female choice for oviposition-substratum. The yeast Saccharomyces cerevisiae proved to be the most nutritional diet, but despite showing the highest survival rates, vertical transmission to F1 was never confirmed. In addition, during the oviposition trials, none of the gravid females was attracted to the yeast substratum. Notably, the two native bacterial strains, Klebsiella sp. and Aeromonas sp., were the preferred oviposition media, the same two bacteria that managed to feed neonates until molting into 2nd instar larvae. Our results not only suggest that Klebsiella sp. or Aeromonas sp. serve as attractants for oviposition habitat selection, but also nurture the most fragile instar, L1, to assure molting into a more resilient stage, L2, while yeast proves to be the most supportive diet for completing development. These experiments unearthed survival traits that might be considered in the future development of strategies of Cx. pipiens control. These studies can be extended to other members of the Pipiens Assemblage.

Díaz-Nieto LM, Gil MF, Lazarte JN, Perotti MA, & Berón CM. 2021

Culex quinquefasciatus carrying Wolbachia is less susceptible to entomopathogenic bacteria.

Scientific Reports 11, 1094.

In an attempt to evaluate the susceptibility of the mosquito Culex quinquefasciatus to bacterial agents, a population naturally infected with a Wolbachia pipientis wPipSJ native strain was tested against the action of three bacterial mosquitocides, Bacillus thuringiensis subsp. israelensis, Bacillus wiedmannii biovar thuringiensis and Lysinibacillus sphaericus. Tests were carried out on mosquito larvae with and without Wolbachia (controls). Cx. quinquefasciatus naturally infected with the native wPipSJ strain proved to be more resistant to the pathogenic action of the three mosquitocidal bacterial strains. Additionally, wPipSJ was fully characterised using metagenome-assembled genomics, PCR–RFLP (PCR-Restriction Fragment Length Polymorphism) and MLST (MultiLocus Sequence Typing) analyses. This Wolbachia strain wPipSJ belongs to haplotype I, group wPip-III and supergroup B, clustering with other mosquito wPip strains, such as wPip PEL, wPip JHB, wPip Mol, and wAlbB; showing the southernmost distribution in America. The cytoplasmic incompatibility phenotype of this strain was revealed via crosses between wildtype (Wolbachia+) and antibiotic treated mosquito populations. The results of the tests with the bacterial agents suggest that Cx. quinquefasciatus naturally infected with wPipSJ is less susceptible to the pathogenic action of mosquitocidal bacterial strains when compared with the antibiotic-treated mosquito isoline and is more susceptible to B. thuringiensis subsp. israelensis than to the other two mosquitocidal agents.

Martinez-Sañudo I, Perotti MA, Scaccini D, Pozzebon A, Marri L, & Mazzon L. 2020

Co-haplotyping symbiont and host to unravel invasion pathways of the exotic pest Halyomorpha halys in Italy.

Scientific Reports 10,18441.

The brown marmorated stink bug Halyomorpha halys (Stål) is a globally invasive species that harbours the primary bacterial symbiont ‘Candidatus Pantoea carbekii’. In this work, P. carbekii was used as another genetic marker to investigate the biodiversity and biogeographical patterns of this important pest, in native and newly invaded areas, especially in Italy. The correlation between the genetic structure of the symbiont and that of its host was studied through the analyses of one bacterial and one host marker, the putative pseudogene ΔybgF and the mitochondrial gene COI, respectively. As a result, five new P. carbekii haplotypes were identified, and an association pattern between host-symbiont haplotypes was observed. Host species showed higher haplotype diversity than symbiont, which can be expected in a long term host-symbiont association. Populations from the north-eastern Italy showed the highest values of genetic diversity for both markers, highlighting that this particular Italian area could be the result of multiple ongoing introductions. Moreover, some of the symbiont-host haplotypes observed were shared only by populations from north-eastern Italy and native areas, especially Japan, suggesting further introductions from this native country to Italy. Overall, our findings improve the understanding of the potential origin of multiple accidental introductions of H. halys in Italy.

Image: Manar Sanad

Berón CM, Díaz-Nieto LM, Lazarte JN, & Lopez RP. 2016

Bacterias como agentes de control biológico de poblaciones de mosquitos [Bacteria as biological control agents of mosquito populations].

In: Investigaciones sobre Mosquitos de Argentina [Research on Mosquitoes in Argentina]. Berón CM, Campos RE, Gleiser R, Díaz-Nieto LM, Salomón OD, & Schweigmann N (eds). Mar del Plata: Universidad Nacional de Mar del Plata; 251-268.

Hubert J, Kopecky J, Nesvorna M, Perotti MA, & Erban T. 2016

Detection and localization of Solitalea-like and Cardinium bacteria in three Acarus siro populations (Astigmata: Acaridae).

Experimental and Applied Acarology 70, 309-327.

Kopecky J, Perotti MA, Nesvorna M, Erban T, & Hubert J. 2013

Cardinium endosymbionts are widespread in synanthropic mite species (Acari: Astigmata).

Journal of Invertebrate Pathology 112, 20-23.

Dubuffet A, Smith JE, Solter L, Perotti M A, Braig HR, & Dunn AM. 2013

Specific detection and localization of microsporidian parasites in invertebrate hosts by using in situ hybridization.

Applied and Environmental Microbiology 79, 385-388.

Hubert J, Kopecký J, Perotti MA, Nesvorná M, Braig HR, Ságová-Marečková M, ..., & Zurek L. 2012

Detection and identification of species-specific bacteria associated with synanthropic mites.

Microbial Ecology 63, 919-928.

Perotti MA & Braig HR. 2011

Eukaryotic ectosymbionts of Acari.

Journal of Applied Entomology 135, 514-523.

Perotti MA, Kirkness EF, Reed DL, & Braig HR. 2009

Endosymbionts of lice.

In: Insect Symbiosis 3. Bourtzis K & TA Miller TA (eds.). Boca Raton: Taylor & Francis; 205-219.

Braig HR, Turner BD, & Perotti MA. 2009

Symbiotic Rickettsia.

In: Insect Symbiosis 3. Bourtzis K & TA Miller TA (eds.). Boca Raton: Taylor & Francis; 221-249

Allen JM, Light JE, Perotti MA, Braig HR, & Reed DL. 2009

Mutational meltdown in primary endosymbionts: Selection limits Muller's ratchet.

PLoS ONE 4, e4969.

Perotti MA, Allen JM, Reed DL, & Braig HR. 2007

Host-symbiont interactions of the primary endosymbiont of human head and body lice.

FASEB Journal 21, 1058-1066.

Allen JM, Reed DL, Perotti MA, & Braig HR. 2007

Evolutionary relationships of "Candidatus Riesia spp.," endosymbiotic Enterobacteriaceae living within hematophagous primate lice.

Applied and Environmental Microbiology 73, 1659-1664.

Perotti MA, Clarke HK, Turner BD, & Braig HR. 2006

Rickettsia as obligate and mycetomic bacteria.

FASEB Journal 20, 2372-2374.

Perotti MA, & Braig HR. 2005

Endosymbionts of Acari.

Phytophaga 14, 457-474.

Perotti MA, Catalá SS, Ormeño AD, Zelazowska M, Bilinski SM, & Braig HR. 2004

The sex ratio distortion in the human head louse is conserved over time.

BMC Genetics 5, e10.