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OBJECTIVE: To investigate the microbiota composition and diversity between autogenous and anautogenous Culex pipiens pallens, so as to provide insights into unraveling the pathogenesis of autogeny in Cx. pipiens pallens. METHODS: Autogenous and anautogenous adult Cx. pipiens pallens samples were collected at 25 ℃, and the hypervariable regions of the microbial 16S ribosomal RNA (16S rRNA) gene was sequenced on the Illumina NovaSeq 6000 sequencing platform. The microbiota abundance and diversity were evaluated using the alpha diversity index, and the difference in the microbiota structure was examined using the beta diversity index. The microbiota with significant differences in the abundance between autogenous and anautogenous adult Cx. pipiens pallens samples was identified using the linear discriminant analysis effect size (LEfSe). RESULTS: The microbiota in autogenous and anautogenous Cx. pipiens pallens samples belonged to 18 phyla, 28 classes, 70 orders, 113 families, and 170 genera, and the dominant phyla included Proteobacteria, Bacteroidetes, and so on. At the genus level, Wolbachia was a common dominant genus, and the relative abundance was (77.6 ± 11.3)% in autogenous Cx. pipiens pallens samples and (47.5 ± 8.5)% in anautogenous mosquito samples, while Faecalibaculum (0.4% ± 0.1%), Dubosiella (0.5% ± 0.0%) and Massilia (0.5% ± 0.1%) were specific species in autogenous Cx. pipiens pallens samples. Alpha diversity analysis showed that higher Chao1 index and ACE index in autogenous Cx. pipiens pallens samples than in anautogenous samples (both P values > 0.05), and lower Shannon index (P > 0.05) and Simpson index (P < 0.05) in autogenous Cx. pipiens pallens samples than in anautogenous samples. LEfSe analysis showed a total of 48 significantly different taxa between autogenous and anautogenous Cx. pipiens pallens samples (all P values < 0.05). CONCLUSIONS: There is a significant difference in the microbiota diversity between autogenous and anautogenous Cx. pipiens pallens.

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Objective To investigate the microbiota composition and diversity between autogenous and anautogenous Culex pipiens pallens, so as to provide insights into unraveling the pathogenesis of autogeny in Cx. pipiens pallens. Methods Autogenous and anautogenous adult Cx. pipiens pallens samples were collected at 25 ℃, and the hypervariable regions of the microbial 16S ribosomal RNA (16S rRNA) gene was sequenced on the Illumina NovaSeq 6000 sequencing platform. The microbiota abundance and diversity were evaluated using the alpha diversity index, and the difference in the microbiota structure was examined using the beta diversity index. The microbiota with significant differences in the abundance between autogenous and anautogenous adult Cx. pipiens pallens samples was identified using the linear discriminant analysis effect size (LEfSe). Results The microbiota in autogenous and anautogenous Cx. pipiens pallens samples belonged to 18 phyla, 28 classes, 70 orders, 113 families, and 170 genera, and the dominant phyla included Proteobacteria, Bacteroidetes, and so on. At the genus level, Wolbachia was a common dominant genus, and the relative abundance was (77.6 ± 11.3)% in autogenous Cx. pipiens pallens samples and (47.5 ± 8.5)% in anautogenous mosquito samples, while Faecalibaculum (0.4% ± 0.1%), Dubosiella (0.5% ± 0.0%) and Massilia (0.5% ± 0.1%) were specific species in autogenous Cx. pipiens pallens samples. Alpha diversity analysis showed that higher Chao1 index and ACE index in autogenous Cx. pipiens pallens samples than in anautogenous samples (both P values > 0.05), and lower Shannon index (P > 0.05) and Simpson index (P < 0.05) in autogenous Cx. pipiens pallens samples than in anautogenous samples. LEfSe analysis showed a total of 48 significantly different taxa between autogenous and anautogenous Cx. pipiens pallens samples (all P values < 0.05). Conclusion There is a significant difference in the microbiota diversity between autogenous and anautogenous Cx. pipiens pallens.

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IMPORTANCE: Previous research has implicated Ornithodoros ticks, including Ornithodoros turicata, as long-term reservoirs of relapsing fever (RF) spirochetes. Considering the tick's long lifespan and their efficiency in maintaining and transferring spirochetes within the population, the infection could persist in a given enzootic focus for decades. However, little is known about the relative importance of horizontal and vertical transmission routes in the persistence and evolution of RF Borrelia. Our observations on the reproductive biology of O. turicata in the absence of vertebrate hosts indicate an additional mechanism by which Borrelia turicatae can be maintained in the environment. This work establishes the foundation for studying O. turicata reproduction and spirochete-vector interactions, which will aid in devising control measures for Ornithodoros ticks and RF spirochetes.

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Aedes koreicus Edwards, 1917 (Hulecoetomyia koreica) is a mosquito (Diptera: Culicidae) from Northeast Asia with a rapidly expanding presence outside its original native range. Over the years, the species has been discovered in several new countries, either spreading after first introduction or remaining localised to limited areas. Notably, recent studies have demonstrated the ability of the species to transmit zoonotic parasites and viruses both in the field and in laboratory settings. Combined with its invasive potential, the possible role of Ae. koreicus in pathogen transmission highlights the public health risks resulting from its invasion. In this study, we used a recently established population from Italy to investigate aspects of biology that influence reproductive success in Ae. koreicus: autogeny, mating behaviour, mating disruption by the sympatric invasive species Aedes albopictus Skuse, 1894, and the presence of the endosymbiont Wolbachia pipientis Hertig, 1936. Our laboratory population did not exhibit autogenic behaviour and required a bloodmeal to complete its ovarian cycle. When we exposed Ae. koreicus females to males of Ae. albopictus, we observed repeated attempts at insemination and an aggressive, disruptive mating behaviour initiated by male Ae. albopictus. Despite this, no sperm was identified in Ae. koreicus spermathecae. Wolbachia, an endosymbiotic bacterium capable of influencing mosquito reproductive behaviour, was not detected in this Ae. koreicus population and, therefore, had no effect on Ae. koreicus reproduction.

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BACKGROUND: Mosquitoes of the Culex pipiens complex are found across the globe and are the focus of many research studies. Among the temperate species C. pipiens sensu stricto (s.s.), two forms are usually described: molestus and pipiens. These two forms are indistinguishable in terms of morphology but show behavioral and physiological differences that may have consequences for their associated epidemiology. The two forms are well defined in the northern part of the species distribution, where autogeny is strictly associated with the molestus form. However, whether the two remain distinct and show the characteristic differences in behavior is less clear in North Africa, at the southern edge of their range. METHODS: The association between autogeny, as determined by ovarian dissection, and molecular forms, based on the CQ11 microsatellite marker, was studied in six Moroccan populations of C. pipiens. RESULTS: An overall low prevalence of autogeny was found at three of the Moroccan regions studied, although it reached 17.5% in the Agadir population. The prevalence of form-specific CQ11 alleles was quite similar across all populations, with the molestus allele being rarer (approx. 15%), except in the Agadir population where it reached 43.3%. We found significant deficits in heterozygotes at the diagnostic CQ11 locus in three populations, but the three other populations showed no significant departure from panmixia, which is in line with the results of a retrospective analysis of the published data. More importantly, we found no association between the autogeny status and CQ11 genotypes, despite the many females analyzed. CONCLUSIONS: There was limited evidence for two discrete forms in Morocco, where individuals carrying pipiens and molestus alleles breed and mate in the same sites and are equally likely to be capable of autogeny. These observations are discussed in the epidemiological context of Morocco, where C. pipiens is the main vector of several arboviruses.

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Most mosquito species are anautogenous, which means they must blood feed on a vertebrate host to produce eggs, while a few are autogenous and can produce eggs without blood feeding. Egg formation is best understood in the anautogenous mosquito Aedes aegypti, where insulin-like peptides (ILPs), ovary ecdysteroidogenic hormone (OEH) and 20-hydroxyecdysone (20E) interact to regulate gonadotrophic cycles. Circulating hemocytes also approximately double in abundance in conjunction with a gonadotrophic cycle, but the factors responsible for stimulating this increase remain unclear. Focusing on Ae. aegypti, we determined that hemocyte abundance similarly increased in intact blood-fed females and decapitated blood-fed females that were injected with ILP3, whereas OEH, 20E or heat-killed bacteria had no stimulatory activity. ILP3 upregulated insulin-insulin growth factor signaling in hemocytes, but few genes - including almost no transcripts for immune factors - were differentially expressed. ILP3 also stimulated circulating hemocytes to increase in two other anautogenous (Anopheles gambiae and Culex quinquefasciatus) and two facultatively autogenous mosquitoes (Aedes atropalpus and Culex pipiens molestus), but had no stimulatory activity in the obligately autogenous mosquito Toxorhynchites amboinensis. Altogether, our results identify ILPs as the primary regulators of hemocyte proliferation in association with egg formation, but also suggest this response has been lost in the evolution of obligate autogeny.

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The insecticide resistance in Triatoma infestans (Klug, 1834) was detected in different areas of its geographical distribution. The mechanisms of resistance involved can affect different biological processes in addition to toxicological ones. Previous studies showed that reproductive efficiency was modified in resistant females compared to susceptible ones. The objective of this study was to compare the autogenic capacity and subsequent reproductive potential between deltamethrin-resistant and susceptible T. infestans. For each toxicological phenotype, pairs were formed between unfed adult females and recently fed adult male, which were separated after confirming copulation. Females were observed weekly until death, and reproductive parameters (initiation of mating, initiation of oviposition, fecundity, fertility and period between mating and initiation of oviposition) were recorded. Females from both toxicological phenotypes showed autogenic capacity. However, a lower proportion of deltamethrin-resistant unfed females laid eggs. Autogenic females showed a higher nutritional status than non-autogenic ones. No other differences in reproductive parameters were found between resistant and susceptible autogenic females. The possible mechanisms underlying the differences observed and their consequences on the spread of resistance are discussed. This is the first report describing the effect of pyrethroid resistance on T. infestans autogeny.

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OBJECTIVES: Culiseta longiareolata is a cosmopolitan species and has implicated in the transmission of avian malaria, tularemia, and arboviruses. Despite the wide distribution of Cs. longiareolata in Iran, little is known about its biology and physiology. The current research was conducted to study the autogeny behavior in this potential vector. During 2018, larvae and pupae were collected from Nazloo region in Urmia City using standard methods. Mosquitoes were reared in cages and fed by 5% sugar in laboratory conditions and were then dissected in phosphate-buffered saline (PBS) under a stereo microscope. RESULTS: In total, 230 adult female Cs. longiareolata mosquitoes were dissected. Egg rafts were observed in the ovary of only 10.86% unfed female mosquitoes. Autogeny behavior is a significant factor in the growth of population without a blood feeding. Therefore, it is necessary to study how autogenous reproduction affects mosquito-borne diseases.

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Culex pipiens molestus Forskål is common in subterranean and aboveground environments in Shanghai, China. However, little is known about its autogeny, fecundity, and other life history traits. In this study, Cx. p. molestus larvae were collected from four different types of underground parking lots and artificially maintained, without blood feeding, in a laboratory. Life history traits parameters were recorded from the F0 to F9 generation. Culex pipiens molestus from Shanghai can autogenously persist for at least 10 generations, and some females can develop more than one egg batch without blood feeding (oviposition rate in Lot C was >100% in some generations). The average number of eggs per raft produced autogenously ranged from 36.94 to 42.19. The average generation time (GT) ranged from 20.06 to 21.30 d, and the pre-oviposition time (POT) ranged from 2.17 to 12.68 d among the generations. Culex pipiens molestus from the four groups had different autogeny, fecundity, and longevity patterns. This variability may result from genetic polymorphism caused by co-occurrence with other Culex pipiens subspecies (Diptera: Culicidae).

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BACKGROUND: The Culex pipiens complex (Diptera: Culicidae) includes the most widespread mosquito species in the world. Members of this complex are the primary enzootic and epidemic vectors of the West Nile virus (genus Flavivirus) in several countries. The two recognized forms of Cx. pipiens (Linnaeus, 1758) - pipiens and molestus - exhibit behavioral and physiological differences. Natural populations of Cx. pipiens were investigated in several sites in Tunisia to evaluate the ecophysiological and molecular characteristics of their forms. RESULTS: The analysis showed the sympatric presence of Cx. pipiens forms and hybrids in all studied sites. Of all the tested larvae of Cx. pipiens, 33.5% were identified as pipiens, 30.8% were identified as molestus, and 35.6% were identified as hybrids. The molestus and hybrid forms were positively correlated with urban habitats and belowground sites while the pipiens form was positively correlated with rural habitats and aboveground sites. Autogeny was expressed in all types of habitats and breeding sites. By contrast with the microsatellite CQ11, the two molecular markers, ace-2 and cytb, did not allow differentiation between the Cx. pipiens forms. CONCLUSIONS: Our study shows the ubiquitous distribution and the plasticity of the different forms of Cx. pipiens in a wide range of ecological conditions. It suggests that the behavioral traits assigned to the forms of Cx. pipiens seem to be more flexible than previously assumed. Our analysis also proves that the microsatellite CQ11 remains an efficient tool for distinguishing between Cx. pipiens forms.

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BACKGROUND: We investigated the ecological differentiation of two members of the Culex pipiens complex, Cx. p. pipiens form pipiens and Cx. p. pipiens form molestus in three sites, El-Kala, M'Sila and Tinerkouk in Algeria. These two forms are the most widespread mosquito vectors in temperate regions exhibiting important behavioural and physiological differences. Nevertheless, this group of potential vectors has been poorly studied, particularly in North Africa. METHODS: Ten larval populations of Cx. p. pipiens were sampled from various above- and underground habitats in three zones representing the three bioclimatic regions in Algeria. The reproduction characteristics were also investigated in the laboratory to define the rates of autogeny and stenogamy. Identification of Cx. p. pipiens members present in Algeria was achieved using a molecular analysis with the microsatellite CQ11 locus. RESULTS: We detected larvae of Cx. p. pipiens in all areas suggesting that the species is a ubiquitous mosquito well adapted to various environments. To our knowledge, this study provides the first molecular evidence of the presence of the Cx. p. pipiens form molestus and hybrids (molestus/pipiens) in Algeria with a high proportion of molestus form (48.3 %) in comparison with hybrids (36.8 %) and pipiens form (14.9 %). CONCLUSIONS: Some unexpected correlations between the proportion of forms pipiens, molestus and hybrids, and mosquito biological characteristics were observed suggesting some epigenetic effects controlling Cx. p. pipiens mating and reproduction. Consequences for pathogen transmission are discussed.

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Aedes aegypti is an anautogenous mosquito that must blood feed on a vertebrate host to produce and lay a clutch of eggs. The rockpool mosquito, Georgecraigius atropalpus, is related to A. aegypti but is a facultatively autogenous species that produces its first clutch of eggs shortly after emerging without blood feeding. Consumption of a blood meal by A. aegypti triggers the release of ovary ecdysteroidogenic hormone (OEH) and insulin-like peptide 3 (ILP3) from the brain, which stimulate egg formation. OEH and ILP3 also stimulate egg formation in G. atropalpus but are released at eclosion independently of blood feeding. These results collectively suggest that blood meal dependent release of OEH and ILP3 is one factor that prevents A. aegypti from reproducing autogenously. Here, we examined two other factors that potentially inhibit autogeny in A. aegypti: teneral nutrient reserves and the ability of OEH and ILP3 to stimulate egg formation in the absence of blood feeding. Measures of nutrient reserves showed that newly emerged A. aegypti females had similar wet weights but significantly lower protein and glycogen reserves than G. atropalpus females when larvae were reared under identical conditions. OEH stimulated non-blood fed A. aegypti females to produce ecdysteroid hormone and package yolk into oocytes more strongly than ILP3. OEH also reduced host seeking and blood feeding behavior, yet females produced few mature eggs. Overall, our results indicate that multiple factors prevent A. aegypti from reproducing autogenously.

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The present study recorded mosquito autogeny for the first time amongst Aedes caspius species in the Eastern region of Saudi Arabia. Laboratory rearing showed an obligatory autogenous species of Ae. caspius since it foregoes blood feeding during its first ovarian cycle, even in the presence of the hosts (CD mouse), but produces its second egg batch only if ingested a blood meal. Both morphological and molecular identification confirmed that both autogenous and anautogenous strains belong to the same species of Ae. caspius. Data from biochemical analysis showed significant 2, 1.6, and 1.4 folds higher total carbohydrates, proteins, and lipids reserves respectively in the fourth larval instar of the autogenous strain compared to that of the anautogenous ones. In addition, exposing the fourth larval instars of autogenous strain to the infection stress by the mosquito larvicidal bacterium, Bacillus thuringiensis var kurstaki has significantly reduced total carbohydrates, proteins and lipids reserves by 29%, 35%, and 46%, respectively, at 12 h postinfection compared to those of uninfected ones. These reductions in nourishment reserves were more pronounced at 24 h postinfection in the case of proteins and lipids, but not carbohydrates. These results may indicate that bacterial infection is a health stress that significantly reduced nourishments reservation, which may interrupt the success of adult autogeny. However, the impact of infection-induced decline in larval nourishments reservation on successful adult autogeny is still to be investigated.

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The ovary development in autogenous and anautogenous strains of Aedes togoi was stud led.Under the laboratory conditions, autogenous and anautogenous strains were selected from the wild caught Aedes togoi, and different stages of ovary development were observed.The experiment demonstrated that the biological characteristics of the ovary development in these two strains were evidently different, such as the size and number of matured follicles, the continuity and the pace of developing pro:esses.The main cause for the differences is the time and amount of vitellogenin deposited in oocytes.

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This report deals with the comparative study on the vitellogenesis in autogenous and anautogenous strains of Aedes togoi. Histochemical and immunohistochemical methods were used. It was found that rule of vitellogenesis is characteristic in different strains within the same species. Synthesis of vitellogenin in autogenous strain begins as soon as post-emergence and the process goes on continuously, up to the oocytes to take in vitellin for maturation. Vitellogenin synthesis in anautogenous strain starts after blood meal, and there is an apparent testing stage before blood feeding. The capacity of vitellogenin synthesis is also different between two strains.