Features of reproduction in laboratory-reared Aedes fluviatilis (Lutz, 1904) (Diptera: Culicidae)

Observations were made on 100 female Aedes fluviatilis (Lutz) maintained individually from the first blood meal onwards and allowed one blood meal during each oviposition cycle, 5% dextrose solution been supplied throughout life. The average length of live was 49.9 ± 17.8 days; the logarithm of the mortality rate increased proportionately to physiological age. The insects took an average of 7.3 ± 3.2 blood meals and produced a mean of 7.9 ± 3.7 clutches of eggs. There was a progressive decrease, proportional to advancing physiological age, in the mean numbers of eggs laid in successive oviposition cycles, in the intervals between blood feeding oviposition, and in the numbers of larvae that hatched. Delayed oviposition, transient sterility and a total loss of fertility were also recorded.

Download Full-text

Assessing the blood-host plasticity and dispersal rate of the malaria vector Anopheles coluzzii

10.1101/424051 ◽

2018 ◽

Cited By ~ 1

Author(s):

James Orsborne ◽

Luis Furuya-Kanamori ◽

Claire L. Jeffries ◽

Mojca Kristan ◽

Abdul Rahim Mohammed ◽

...

Keyword(s):

Blood Meal ◽

Disease Transmission ◽

Blood Feeding ◽

Host Choice ◽

Anopheles Coluzzii ◽

Dispersal Rate ◽

Blood Digestion ◽

Novel Method ◽

Blood Meal Digestion ◽

Blood Meals

AbstractDifficulties with observing the dispersal of insect vectors in the field have hampered understanding of several aspects of their behaviour linked to disease transmission. Here, a novel method based on detection of blood-meal sources is introduced to inform two critical and understudied mosquito behaviours: plasticity in the malaria vector’s blood-host choice and vector dispersal. Strategically located collections of Anopheles coluzzii from a malaria-endemic village of southern Ghana showed statistically significant variation in host species composition of mosquito blood-meals. Trialling a new sampling approach gave the first estimates for the remarkably local spatial scale across which host choice is plastic. Using quantitative PCR, the blood-meal digestion was then quantified for field-caught mosquitoes and calibrated according to timed blood digestion in colony mosquitoes. We demonstrate how this new ‘molecular Sella score’ approach can be used to estimate the dispersal rate of blood-feeding vectors caught in the field.

Download Full-text

Malaria parasite immune evasion and adaptation to its mosquito host is influenced by the acquisition of multiple blood meals

10.1101/801480 ◽

2019 ◽

Cited By ~ 3

Author(s):

Hyeogsun Kwon ◽

Rebekah A. Reynolds ◽

Maria L. Simões ◽

George Dimopoulos ◽

Ryan C. Smith

Keyword(s):

Blood Meal ◽

Blood Feeding ◽

Parasite Development ◽

Protein Meal ◽

Infected Blood ◽

Adult Lifespan ◽

Multiple Blood ◽

The Impact ◽

Immune Detection ◽

Blood Meals

AbstractA minimum of two blood meals are required for a mosquito to acquire and transmit malaria, yet Anopheles mosquitoes frequently obtain additional blood meals during their adult lifespan. To determine the impact of subsequent blood-feeding on parasite development in Anopheles gambiae, we examined rodent and human Plasmodium parasite infection with or without an additional non-infected blood meal. We find that an additional blood meal significantly reduces P. berghei immature oocyst numbers, yet does not influence mature oocysts that have already begun sporogony. This is in contrast to experiments performed with the human parasite, P. falciparum, where an additional blood meal does not affect oocyst numbers. These observations are reproduced when mosquitoes were similarly challenged with an artificial protein meal, suggesting that parasite losses are due to the physical distension of the mosquito midgut. We provide evidence that feeding compromises the integrity of the midgut basal lamina, enabling the recognition and lysis of immature P. berghei oocysts by the mosquito complement system. Moreover, we demonstrate that additional feeding promotes P. falciparum oocyst growth, suggesting that human malaria parasites exploit host resources provided with blood-feeding to accelerate their growth. This contrasts experiments with P. berghei, where the size of surviving oocysts is independent of an additional blood meal. Together, these data demonstrate differences in the ability of Plasmodium species to evade immune detection and adapt to utilize host resources at the oocyst stage, representing an additional, yet unexplored component of vectorial capacity that has important implications for transmission of malaria.

Download Full-text

Blood meal sources of Anopheles vectors of human malaria in Malawi: Implications for malaria transmission and effectiveness of interventions

10.21203/rs.3.rs-841591/v1 ◽

2021 ◽

Author(s):

Rex B Mbewe ◽

John Keven ◽

Themba Mzilahowa ◽

Lauren Cohee ◽

Miriam K Laufer ◽

...

Keyword(s):

Human Blood ◽

Blood Meal ◽

Light Trap ◽

Blood Feeding ◽

Malaria Vectors ◽

Rural Villages ◽

Human Malaria ◽

Anopheles Vectors ◽

Wide Availability ◽

Blood Meals

Abstract BackgroundSelection of blood meal hosts by mosquitoes is a key variable in the vectorial capacity of Anopheles mosquitoes for human malaria. Blood feeding on humans is likely to be modulated by use of different types of long-lasting insecticidal nets (LLINs) and the effectiveness of LLINs is impacted by the relative intensity of insecticide resistance. The aim of this study was to test the hypothesis that LLINs containing pyrethroid and the synergist piperonyl butoxide (PBO) would lead to a reduction of human host utilization than LLINs containing only pyrethroid and that blood feeding patterns of Anopheles in Malawi compromise malaria interventions.MethodsFemale Anopheles mosquitoes were sampled indoors from May 2019 through April 2020 by aspiration, pyrethrum spray catch, and CDC light trap in rural villages of Namanolo (conventional nets) and Ntaja (PBO nets) in Balaka and Machinga districts respectively. Anopheles species, blood meal sources, and infection with Plasmodium falciparum in the head and thorax of individual mosquitoes were determined with PCR.ResultsOf a total of 6,585 Anopheles females sampled indoors in 203 houses, 633 (9.6%) were blood-fed and consisted of An. arabiensis (44.1% (n = 279)), An. gambiae s.s (16.2% (n = 103)), An. funestus s.s (33.5% (n = 212)), An. parensis 0.3% (n = 2), and unidentified Anopheles spp (5.8% (n = 37)). Of the 541 mosquitoes (85.5%) successfully identified blood meals, 436 (81.0%) were solely human, 28 (5.2%) goat, 11 (2.0%) dog, 60 (11.1%) mixed goat-human, 5 (0.9%) dog-human, and 1 dog-goat. Human blood index and EIR was high in Namanolo than Ntaja (0.96 vs 0.89 (p = 0.001) and 0.11 vs 0.06 infective bites per person per year respectively) despite high net ownership (92%) and nightly use (75%) rates. Relative to host availability, non-human hosts were over selected in the two sites.ConclusionThe use of PBO nets was associated with lower HBI and EIR, however, the wide availability of LLINs was still associated with extensive successful human blood meals by the main malaria vectors in Malawi. The presence of a small fraction of mixed blood meals indicates constrained plasticity of Anopheles vectors to switch to non-human hosts and circumvent malaria control interventions.

Download Full-text

Pre-mating Blood Feeding by Anopheles pharoensis (Diptera: Culicidae) and Its Effects on Mating, Longevity and Egg Production

Journal of Entomological Science ◽

10.18474/0749-8004-25.1.57 ◽

1990 ◽

Vol 25 (1) ◽

pp. 57-63

Author(s):

Adel S. El-Akad ◽

J. G. Humphreys

Keyword(s):

Blood Meal ◽

Egg Production ◽

Ovarian Development ◽

Reproductive Potential ◽

Blood Feeding ◽

Field Observations ◽

Laboratory Studies ◽

The Third ◽

Anopheles Pharoensis ◽

Blood Meals

Field observations and laboratory studies were conducted to determine the effects of a pre-mating blood meal on mating, ovarian development and oviposition in Anopheles pharoensis (Theobald). Approximately 24% of the females blood feed before mating; however, swollen abdomens of blood-fed females interfere with the mating process. In females which mated prior to first blood meal, first oviposition occurred at 6.6 days and required only a single blood meal. A second blood meal takes them to the second oviposition in an additional 2.5 days; the third oviposition required 1.4 blood meals and occurred 3 days after the second oviposition. Blood-fed unmated females reach first oviposition at 13.4 days and require an average of 4 blood meals prior to the first oviposition. At this age, the female is chronologically old and even if mating now occurs, egg production is greatly reduced and continues to decrease through subsequent ovipositions until death. The taking of a blood meal prior to mating greatly decreases the reproductive potential of this species.

Download Full-text

Frequency and Mortality Risk Factors of Acute Ischemic Stroke in Emergency Department in Burkina Faso

Stroke Research and Treatment ◽

10.1155/2020/9745206 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7

Author(s):

Alfred Anselme Dabilgou ◽

Alassane Dravé ◽

Julie Marie Adeline Kyelem ◽

Saïdou Ouedraogo ◽

Christian Napon ◽

...

Keyword(s):

Risk Factors ◽

Emergency Department ◽

Ischemic Stroke ◽

Mortality Rate ◽

Acute Ischemic Stroke ◽

Mortality Risk ◽

Average Length ◽

University Teaching ◽

Vascular Risk ◽

The Mean

Objective. To determine the prevalence of ischemic stroke deaths and their predictive factors in the Emergency Department at Yalgado Ouedraogo University Teaching Hospital (YOUTH). Methodology. This was a retrospective study with an analytical and descriptive focus over a period of three years from January 1, 2015, to December 31, 2017. Results. During the study period, 302 acute ischemic stroke patients with a mean age of 62.2±14.26 years were included. Atrial hypertension was the most common vascular risk factor in 52.5%. On admission, 34.8% of patients had loss of consciousness. The mean time to perform brain CT was 1.5 days. The average length of stay was 4 days. Electrocardiogram, echocardiography, and cervical Doppler were not performed during hospitalization in ED. The mortality rate was 39%, respectively, 37.6% in male and 41.6% in female. The mean age of patients who died in ED was 63.6±13.52 years. Hypertension was the most common vascular risk factors in 54.2% of death. After logistic regression, the predictors of death were past history of heart disease, consciousness disorders, hyperthermia, hyperglycemia on admission, poststroke pneumonia, and urinary tract infection. Conclusions. Acute ischemic stroke was frequent in Emergency Department with high mortality rate. The mortality risk factors were the same than those found in literature. This higher mortality can be avoided by early diagnosis and an adequate management.

Download Full-text

Blood meal source and mixed blood-feeding influence gut bacterial community composition in Aedes aegypti

Parasites & Vectors ◽

10.1186/s13071-021-04579-8 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Ephantus J. Muturi ◽

Teresia M. Njoroge ◽

Christopher Dunlap ◽

Carla E. Cáceres

Keyword(s):

Bacterial Community ◽

Aedes Aegypti ◽

Gut Microbiota ◽

Microbial Communities ◽

Blood Meal ◽

Host Species ◽

Bacterial Community Composition ◽

Blood Feeding ◽

Mixed Blood ◽

Blood Meals

Abstract Background The guts of blood-sucking insects host a community of bacteria that can shift dramatically in response to biotic and abiotic factors. Identifying the key factors structuring these microbial communities has important ecological and epidemiological implications. Methods We used the yellow fever mosquito, Aedes aegypti, to investigate the impact of mixed blood meals on gut microbiota of vector mosquitoes. Adult females were experimentally fed on sugar or blood from chicken, rabbit or a mixture of chicken and rabbit blood, and their gut microbiota were characterized using 16S rRNA gene amplification and MiSeq sequencing. Results The gut bacterial communities of mosquitoes fed on the three blood meal treatments clustered separately, suggesting that host species identity and mixed blood-feeding are key determinants of gut bacterial community composition in mosquitoes. Mixed blood meal had a synergistic effect on both operational taxonomic unit (OTU) richness and the Shannon diversity index, suggesting that mixed blood-feeding can offset the nutritional deficit of blood meals from certain host species. The microbial communities observed in this study were distinct from those identified from similarly fed Ae. aegypti from our previous study. Conclusions These findings demonstrate that vector host-feeding preferences can influence gut microbial composition and diversity, which could potentially impact pathogen acquisition and transmission by the vector. The results also demonstrate that different microenvironmental conditions within the laboratory may play an important role in structuring the microbial communities of independently reared mosquito colonies.

Download Full-text

Assessing the blood meal hosts of Culex quinquefasciatus and Aedes taeniorhynchus in Isla Santa Cruz, Galápagos

Parasites & Vectors ◽

10.1186/s13071-019-3835-7 ◽

2019 ◽

Vol 12 (1) ◽

Author(s):

Samoa Asigau ◽

Sawsan Salah ◽

Patricia G. Parker

Keyword(s):

Feeding Behavior ◽

Culex Quinquefasciatus ◽

Blood Meal ◽

Disease Transmission ◽

Avian Malaria ◽

Mosquito Species ◽

Blood Feeding ◽

Santa Cruz ◽

Aedes Taeniorhynchus ◽

Blood Meals

Abstract Background Blood meal host selection by mosquito vectors is an important component in understanding disease dynamics of pathogens that threaten endemic fauna in isolated islands such as Galápagos. Research on the feeding behavior of mosquitoes can provide clues to the hosts and vectors involved in disease transmission. This information is particularly critical for endemic wildlife fauna in island systems that have evolved without resistance to novel diseases such as avian malaria. The aims of this study were to determine the blood-feeding patterns of two species of mosquitoes found in Galápagos and discuss how their feeding behavior may influence the transmission of pathogens such as avian malaria. Methods In the summer of 2015, we sampled two mosquito species (Aedes taeniorhynchus and Culex quinquefasciatus) across 18 different sites on Isla Santa Cruz, which is the second largest island in Galápagos and has the largest human population. We trapped mosquitoes using CDC light traps and CDC gravid traps and identified sources of blood meals for engorged mosquitoes by sequencing a portion of the vertebrate mitochondrial cytochrome b gene. Results Out of 947 female mosquitoes captured, 320 were blood-fed, and PCR amplifications were successful for 301 of the blood meals. Results revealed that both Aedes taeniorhynchus and Culex quinquefasciatus feed from a variety of vertebrate taxa, numerically dominated by humans on Isla Santa Cruz. Conclusions The high proportion of mammalian blood meals could represent locally available and abundant hosts on Santa Cruz. However, host surveys and estimates of relative abundances of vertebrate species will need to accompany mosquito trapping studies on non-inhabited and inhabited islands in Galápagos to further validate this.

Download Full-text

Mosquito blood-feeding patterns and nesting behavior of American crows, an amplifying host of West Nile virus

Parasites & Vectors ◽

10.1186/s13071-021-04827-x ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Sarah S. Wheeler ◽

Conor C. Taff ◽

William K. Reisen ◽

Andrea K. Townsend

Keyword(s):

West Nile Virus ◽

Blood Meal ◽

Blood Feeding ◽

West Nile ◽

Active Nest ◽

Transmission Cycle ◽

Resting Sites ◽

Mosquito Sampling ◽

American Crows ◽

Blood Meals

Abstract Background Although American crows are a key indicator species for West Nile virus (WNV) and mount among the highest viremias reported for any host, the importance of crows in the WNV transmission cycle has been called into question because of their consistent underrepresentation in studies of Culex blood meal sources. Here, we test the hypothesis that this apparent underrepresentation could be due, in part, to underrepresentation of crow nesting habitat from mosquito sampling designs. Specifically, we examine how the likelihood of a crow blood meal changes with distance to and timing of active crow nests in a Davis, California, population. Methods Sixty artificial mosquito resting sites were deployed from May to September 2014 in varying proximity to known crow nesting sites, and Culex blood meal hosts were identified by DNA barcoding. Genotypes from crow blood meals and local crows (72 nestlings from 30 broods and 389 local breeders and helpers) were used to match mosquito blood meals to specific local crows. Results Among the 297 identified Culex blood meals, 20 (6.7%) were attributable to crows. The mean percentage of blood meals of crow origin was 19% in the nesting period (1 May–18 June 2014), but 0% in the weeks after fledging (19 June–1 September 2014), and the likelihood of a crow blood meal increased with proximity to an active nest: the odds that crows hosted a Culex blood meal were 38.07 times greater within 10 m of an active nest than > 10 m from an active nest. Nine of ten crow blood meals that could be matched to a genotype of a specific crow belonged to either nestlings in these nests or their mothers. Six of the seven genotypes that could not be attributed to sampled birds belonged to females, a sex bias likely due to mosquitoes targeting incubating or brooding females. Conclusion Data herein indicate that breeding crows serve as hosts for Culex in the initial stages of the WNV spring enzootic cycle. Given their high viremia, infected crows could thereby contribute to the re-initiation and early amplification of the virus, increasing its availability as mosquitoes shift to other moderately competent later-breeding avian hosts.

Download Full-text

Pilonidal Sinus: How to Choose Between Excision and Open Granulation Versus Excision and Primary Closure?

Swiss Surgery ◽

10.1024/1023-9332.8.6.255 ◽

2002 ◽

Vol 8 (6) ◽

pp. 255-258 ◽

Cited By ~ 28

Author(s):

Perruchoud ◽

Vuilleumier ◽

Givel

Keyword(s):

Hospital Stay ◽

Pilonidal Sinus ◽

Primary Closure ◽

Average Length ◽

Length Of Hospital Stay ◽

Healing Time ◽

Incision And Drainage ◽

The Mean ◽

Primary Healing

Aims: The purpose of this study was to evaluate excision and open granulation versus excision and primary closure as treatments for pilonidal sinus. Subjects and methods: We evaluated a group of 141 patients operated on for a pilonidal sinus between 1991 and 1995. Ninety patients were treated by excision and open granulation, 34 patients by excision and primary closure and 17 patients by incision and drainage, as a unique treatment of an infected pilonidal sinus. Results: The first group, receiving treatment of excision and open granulation, experienced the following outcomes: average length of hospital stay, four days; average healing time; 72 days; average number of post-operative ambulatory visits, 40; average off-work delay, 38 days; and average follow-up time, 43 months. There were five recurrences (6%) in this group during the follow-up period. For the second group treated by excision and primary closure, the corresponding outcome measurements were as follows: average length of hospital stay, four days; average healing time, 23 days; primary healing failure rate, 9%; average number of post-operative ambulatory visits, 6; average off-work delay, 21 days. The average follow-up time was 34 months, and two recurrences (6%) were observed during the follow-up period. In the third group, seventeen patients benefited from an incision and drainage as unique treatment. The mean follow-up was 37 months. Five recurrences (29%) were noticed, requiring a new operation in all the cases. Discussion and conclusion: This series of 141 patients is too limited to permit final conclusions to be drawn concerning significant advantages of one form of treatment compared to the other. Nevertheless, primary closure offers the advantages of quicker healing time, fewer post-operative visits and shorter time off work. When a primary closure can be carried out, it should be routinely considered for socio-economical and comfort reasons.

Download Full-text

The global dynamics of stochastic Holling type II predator-prey models with non constant mortality rate

Filomat ◽

10.2298/fil1718811z ◽

2017 ◽

Vol 31 (18) ◽

pp. 5811-5825

Author(s):

Xinhong Zhang

Keyword(s):

Mortality Rate ◽

Stochastic Model ◽

Sufficient Conditions ◽

Positive Periodic Solution ◽

Global Dynamics ◽

Type Ii ◽

Predator Prey ◽

Persistence In The Mean ◽

The Mean ◽

Predator Prey Models

In this paper we study the global dynamics of stochastic predator-prey models with non constant mortality rate and Holling type II response. Concretely, we establish sufficient conditions for the extinction and persistence in the mean of autonomous stochastic model and obtain a critical value between them. Then by constructing appropriate Lyapunov functions, we prove that there is a nontrivial positive periodic solution to the non-autonomous stochastic model. Finally, numerical examples are introduced to illustrate the results developed.

Download Full-text