scholarly journals Oral Susceptibility to Ivermectin is Over Fifty Times Greater in a Wild Population of Anopheles Albimanus Mosquitoes from Belize than the STECLA Laboratory Reference Strain of A. Albimanus

2021 ◽  
Author(s):  
Staci M. Dreyer ◽  
Kelsey J. Morin ◽  
Marla Magaña ◽  
Marie Pott ◽  
Donovan Leiva ◽  
...  
Keyword(s):  
Reference Strain ◽  
Laboratory Strain ◽  
Initial Assessment ◽  
Malaria Vector Control ◽  
Toxicity Screening ◽  
Anopheles Albimanus ◽  
Anopheles Species ◽  
Host Seeking ◽  
Membrane Feeding ◽  
Genomic Studies

Abstract Background: The STECLA strain of Anopheles albimanus Wiedemann has been in continuous colony for many years and is the reference strain on which genomic studies for the species are based. Recently, the STECLA strain was demonstrated to be much less susceptible to ivermectin ingested in a blood meal (LC 50 of 1468 ng/ml) than all other Anopheles species tested to-date (LC 50 values range from 7 – 56 ng/ml). The ability of A. albimanus to survive ingestion of ivermectin at concentrations far beyond that typically found in the blood of ivermectin-treated people or livestock ( i.e ., 30 – 70 ng/ml) could invalidate the use of ivermectin as a malaria vector control strategy in areas where A. albimanus is a primary vector. Methods: To investigate this, we captured host-seeking A. albimanus in northern Belize and conducted membrane feeding bioassays of ivermectin, using the same methods as described earlier with the STECLA strain. Results: Field-collected A. albimanus in Belize were 55 times more susceptible to ingested ivermectin than were the STECLA reference strain. Oral susceptible to ivermectin in wild A. albimanus from Belize (LC 50 of 26 ng/ml) was equivalent to that of other Anopheles species tested. Conclusion: Contrary to our initial assessment using a highly inbred laboratory strain of mosquito, we show that ivermectin treatment of livestock could reduce A. albimanus populations in areas of Central America and the Caribbean where malaria transmission may occur. Future toxicity screening of ivermectin and other systemic parasiticides for malaria control should consider examining wild populations of the vector species being targeted.

scholarly journals Optimization of a Membrane Feeding Assay for Plasmodium vivax Infection in Anopheles albimanus

2016 ◽  
Vol 10 (6) ◽  
pp. e0004807 ◽  
Author(s):  
Andrés F. Vallejo ◽  
Kelly Rubiano ◽  
Andres Amado ◽  
Amy R. Krystosik ◽  
Sócrates Herrera ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Vivax Infection ◽  
Anopheles Albimanus ◽  
Feeding Assay ◽  
Membrane Feeding ◽  
Membrane Feeding Assay

scholarly journals Host-seeking behavior and hourly biting rhythm of vectors in malaria endemic district of Arba Minch area, Southwest Ethiopia

2020 ◽  
Author(s):  
Melkam Abiye Zeru ◽  
Simon Shibru ◽  
Fekadu Massebo
Keyword(s):  
Malaria Vector ◽  
Negative Binomial ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Southwest Ethiopia ◽  
Anopheles Mosquitoes ◽  
Host Seeking ◽  
Human Landing ◽  
Seeking Behavior ◽  
The Impact

Abstract Background The early and outdoor biting behaviors of malaria vectors are among the key challenges in malaria control. Hence, understanding the host-seeking behavior and the peak biting time of malaria vectors is important in malaria vector control programs. This study assessed the host-seeking behavior and hourly biting activity of malaria mosquitoes in Chano Mille village in Arba Minch district, southwest Ethiopia. Methods The first trial was done by keeping cattle together with human that collects the entered mosquitoes in tent, while the other was done by keeping cattle outside a 1 m distance from human collector inside a tent. In both trials, mosquito collation was done inside tents baited by cattle and human using human landing catches (HLC) techniques. Four human volunteers’ were recruited and trained to collect mosquitoes in the four tents from 18:00-24:00 for three months. Two tents were selected randomly for human alone and two for cattle baited collections in the first night and then rotated to minimize the variation due to location of tents and collectors skill. The tent trial was done close to the shore of the Lake Abaya to minimize the interference of other animals on mosquito movement. The peak biting hour of malaria vectors was assessed within a Chano village from 18:00-6:00. Mosquito collation was done both indoor and outdoor by HLC. Morphological speciation of Anopheles mosquitoes was done. The sporozoite infectivity status of Anopheles pharoensis was examined using enzyme-linked immuno-sorbent assay technique. The data was analyzed using a Generalized Estimating Equations with a negative binomial distribution. Results An. pharoensis, An. gambiae complex and An. tenebrosus were the three species documented during the trial. Keeping cattle together with human collector inside the tent attracted 42% ( P < 0.001) more An. pharoensis compared to human alone tent. Also, keeping cattle outside near to a tent with human at 1 m distance, attracted the entering An. pharoensis into the tent inside with human by 46% ( P = 0.002) than human in a tent with no cattle outside the same tent. The impact was not significant for An. gambiae complex and An. tenebrosus. Anopheles pharoensis and An. gambiae complex showed early night biting activity with peak biting from 19.00-20:00 which was significant for both An. gambiae complex ( P < 0.001) and An. pharoensis ( P = 0.015). Anopheles gambiae complex was mainly biting humans outdoor in the village. Conclusions Finally, keeping cattle within and close to human dwellings could increase malaria vectors bite exposure particularly to the zoophilic malaria vector An. pharoensis and, hence deployment of cattle far from human residence could be recommended to reduce the human exposure. The outdoor and early hours biting behavior of the An. gambiae complex could be a threat for success of current indoor based interventions and hence, tools could be designed to reduce this threat.

scholarly journals Does membrane feeding compromise the quality ofAedes aegyptimosquitoes?

2019 ◽  
Author(s):  
Perran A. Ross ◽  
Meng-Jia Lau ◽  
Ary A. Hoffmann
Keyword(s):  
Aedes Aegypti ◽  
Disease Control ◽  
Inbreeding Depression ◽  
Mass Rearing ◽  
Feeding Rates ◽  
Female Reproduction ◽  
Control Programs ◽  
Host Seeking ◽  
Membrane Feeding ◽  
Host Cues

AbstractModifiedAedes aegyptimosquitoes are being mass-reared for release in disease control programs around the world. Releases involving female mosquitoes rely on them being able to seek and feed on human hosts. To facilitate the mass-production of mosquitoes for releases, females are often provided blood through artificial membrane feeders. When reared across generations there is a risk that mosquitoes will adapt to feeding on membranes and lose their ability to feed on human hosts. To test adaptation to membrane feeding, we selected replicate populations ofAe. aegyptifor feeding on either human arms or membrane feeders for at least 8 generations. Membrane-selected populations suffered fitness costs, likely due to inbreeding depression arising from bottlenecks. Membrane-selected females had higher feeding rates on membranes than human-selected ones, suggesting adaptation to membrane feeding, but they maintained their attraction to host cues and feeding ability on humans despite a lack of selection for these traits. Host-seeking ability in small laboratory cages did not differ between populations selected on the two blood sources, but membrane-selected females were compromised in a semi-field enclosure where host-seeking was tested over a longer distance. Our findings suggest thatAe. aegyptimay adapt to feeding on blood provided artificially, but this will not substantially compromise field performance or affect experimental assessments of mosquito fitness. However, large population sizes during mass rearing with membrane feeders should be maintained to avoid bottlenecks which lead to inbreeding depression.Author summaryWith modified mosquitoes being mass-reared for release in disease control programs, there is interest in understanding factors that can affect the quality of release stocks. In the laboratory, membrane feeding devices are often used to provide blood to female mosquitoes which they need to lay eggs. Over time, mosquitoes could adapt to membrane feeding and lose their preference for (or ability to feed on) natural hosts. Adaptation could affect the performance of lab-reared mosquitoes when deployed in the field, especially if the success of disease control programs relies on female reproduction such as in gene drive orWolbachia-based approaches. We tested to see ifAedes aegyptimosquitoes, the principal vectors of dengue virus, would adapt to feeding on blood provided via membranes. We found some evidence of adaptation, with membrane-selected mosquitoes having higher feeding rates on membranes, but this didn’t affect their ability to feed on humans or their attraction to host cues. Although membrane feeding alone does not substantially affect mosquito quality, it can lead to inbreeding depression if populations pass through bottlenecks as they adapt to feeding on blood provided artificially. Our results may inform mass-rearing programs involving the release of modified female mosquitoes.

scholarly journals Genome Report: Whole Genome Sequence and Annotation of the Parasitoid Jewel Wasp Nasonia giraulti Laboratory Strain RV2X[u]

2020 ◽  
Vol 10 (8) ◽  
pp. 2565-2572 ◽  
Author(s):  
Xiaozhu Wang ◽  
Yogeshwar D. Kelkar ◽  
Xiao Xiong ◽  
Ellen O. Martinson ◽  
Jeremy Lynch ◽  
...  
Keyword(s):  
De Novo ◽  
Rapid Development ◽  
Laboratory Strain ◽  
Whole Genome Sequence ◽  
High Quality ◽  
Important Species ◽  
A Genome ◽  
Behavioral Expression ◽  
Genomic Studies ◽  
Low Coverage

Jewel wasps in the genus of Nasonia are parasitoids with haplodiploidy sex determination, rapid development and are easy to culture in the laboratory. They are excellent models for insect genetics, genomics, epigenetics, development, and evolution. Nasonia vitripennis (Nv) and N. giraulti (Ng) are closely-related species that can be intercrossed, particularly after removal of the intracellular bacterium Wolbachia, which serve as a powerful tool to map and positionally clone morphological, behavioral, expression and methylation phenotypes. The Nv reference genome was assembled using Sanger, PacBio and Nanopore approaches and annotated with extensive RNA-seq data. In contrast, Ng genome is only available through low coverage resequencing. Therefore, de novo Ng assembly is in urgent need to advance this system. In this study, we report a high-quality Ng assembly using 10X Genomics linked-reads with 670X sequencing depth. The current assembly has a genome size of 259,040,977 bp in 3,160 scaffolds with 38.05% G-C and a 98.6% BUSCO completeness score. 97% of the RNA reads are perfectly aligned to the genome, indicating high quality in contiguity and completeness. A total of 14,777 genes are annotated in the Ng genome, and 72% of the annotated genes have a one-to-one ortholog in the Nv genome. We reported 5 million Ng-Nv SNPs which will facility mapping and population genomic studies in Nasonia. In addition, 42 Ng-specific genes were identified by comparing with Nv genome and annotation. This is the first de novo assembly for this important species in the Nasonia model system, providing a useful new genomic toolkit.

scholarly journals Temperature and Sugar Feeding Effects on the Activity of a Laboratory Strain of Aedes aegypti

Insects ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 347 ◽  
Author(s):  
Irvin Forde Upshur ◽  
Elizabeth Annadel Bose ◽  
Cameron Hart ◽  
Chloé Lahondère
Keyword(s):  
Aedes Aegypti ◽  
Mosquito Species ◽  
Thermal Conditions ◽  
Laboratory Strain ◽  
Blood Feeding ◽  
Effect Of Temperature ◽  
Total Carbohydrate ◽  
Sugar Feeding ◽  
Host Seeking ◽  
Invasive Mosquito

Aedes aegypti is an invasive mosquito species that is expected to expand its global distribution through climate change. As poikilotherms, mosquitoes are greatly affected by the temperature of the environment which can impact host-seeking, blood-feeding, and flight activity as well as survival and ability to transmit pathogens. However, an important aspect of mosquito biology on which the effect of temperature has not been investigated is water and sugar-feeding and how access to a sugar source might affect the insect’s activity and survival under different thermal conditions. To close this knowledge gap, we relied on actometer experiments to study the activity of both female and male Ae. aegypti at 20 °C, 25 °C, and 30 °C, providing either water or 10% sucrose to the insects. We then measured the total carbohydrate contents of alive mosquitoes using the anthrone protocol. Survival was assessed and compared between all groups. Results from this study will inform on the thermal biology of Ae. aegypti mosquitoes and how access to sugar affects their activity.

scholarly journals Pyrethroid exposure altersAnopheles albimanusmicrobiota and resistant mosquitoes harbor more insecticide-metabolizing bacteria

2019 ◽  
Author(s):  
Nsa Dada ◽  
Juan C. Lol ◽  
Ana Cristina Benedict ◽  
Francisco López ◽  
Mili Sheth ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Malaria Vector ◽  
Bacterial Communities ◽  
Pyrethroid Resistance ◽  
Malaria Vector Control ◽  
Anopheles Albimanus ◽  
Larval Cuticle ◽  
Specific Effects ◽  
First Time ◽  
Time Type

AbstractA deeper understanding of the mechanisms underlying insecticide resistance is needed to mitigate its threat to malaria vector control. Building upon our earlier identified associations between mosquito microbiota and insecticide resistance, we demonstrate for the first time, type-specific effects of pyrethroid exposure on internal and cuticle surface bacteria in adult progeny of field-collectedAnopheles albimanus. In contrast, larval cuticle surface—but not internal—bacteria were affected by pyrethroid exposure. Being over five-folds more abundant in pyrethroid resistant adults, as compared to susceptible or non-insecticide-exposed mosquitoes,Klebsiella(alphacypermethrin),PantoeaandAsaia(permethrin) were identified as potential markers of pyrethroid resistance inAn. albimanus. We also show for the first time thatAn. albimanuslarvae and adult cuticles harbor more diverse bacterial communities than their internal microbial niches. Our findings indicate insecticide selection pressures on mosquito microbiota, and support the hypothesis of an undescribed microbe-mediated mechanism of insecticide metabolism in mosquitoes.

scholarly journals Physical Mapping of the Anopheles (Nyssorhynchus) darlingi Genomic Scaffolds

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 164
Author(s):  
Míriam Silva Rafael ◽  
Leticia Cegatti Bridi ◽  
Igor V. Sharakhov ◽  
Osvaldo Marinotti ◽  
Maria V. Sharakhova ◽  
...  
Keyword(s):  
Physical Mapping ◽  
Genomic Dna ◽  
Chromosomal Rearrangements ◽  
Polytene Chromosomes ◽  
Anopheles Darlingi ◽  
Anopheles Albimanus ◽  
Anopheles Species ◽  
Homologous Sequences ◽  
Genome Assemblies

The genome assembly of Anopheles darlingi consists of 2221 scaffolds (N50 = 115,072 bp) and has a size spanning 136.94 Mbp. This assembly represents one of the smallest genomes among Anopheles species. Anopheles darlingi genomic DNA fragments of ~37 Kb were cloned, end-sequenced, and used as probes for fluorescence in situ hybridization (FISH) with salivary gland polytene chromosomes. In total, we mapped nine DNA probes to scaffolds and autosomal arms. Comparative analysis of the An. darlingi scaffolds with homologous sequences of the Anopheles albimanus and Anopheles gambiae genomes identified chromosomal rearrangements among these species. Our results confirmed that physical mapping is a useful tool for anchoring genome assemblies to mosquito chromosomes.

scholarly journals Cryogenically preserved RBCs support gametocytogenesis of Plasmodium falciparum in vitro and gametogenesis in mosquitoes

2018 ◽  
Author(s):  
Ashutosh K. Pathak ◽  
Justine C. Shiau ◽  
Matthew B. Thomas ◽  
Courtney Murdock
Keyword(s):  
Plasmodium Falciparum ◽  
Laboratory Strain ◽  
Parasite Development ◽  
Physico Chemical ◽  
Membrane Feeding ◽  
Using Data ◽  
Fresh Rbcs ◽  
Cryo Preservation ◽  
Universal Substrate

AbstractBackgroundThe malaria Eradication Research Agenda (malERA) has identified human-to-mosquito transmission of Plasmodium falciparum as a major target for eradication. The cornerstone for identifying and evaluating transmission in the laboratory is small membrane feeding assays (SMFAs) where mature gametocytes of P. falciparum generated in vitro are offered to mosquitoes as part of a blood-meal. However, propagation of “infectious” gametocytes requires 10-12 days with considerable physico-chemical demands imposed on host RBCs and thus, “fresh” RBCs that are ≤1-week old post-collection are generally recommended. However, in addition to the costs, physico-chemical characteristics unique to RBC donors may confound reproducibility and interpretation of SMFAs. Cryogenic storage of RBCs (cryo-preserved RBCs herein) is approved by the European and US FDAs as an alternative to refrigeration (4°C) for preserving RBC quality and while cryo-preserved RBCs have been used for in vitro cultures of other Plasmodia and the asexual stages of P. falciparum, none of the studies required RBCs to support parasite development for >4 days.ResultsUsing the standard laboratory strain, P. falciparum NF54, we first demonstrate that cryo-preserved RBCs preserved in the gaseous phase of liquid nitrogen and thawed after storage for 1, 4, 8 and 12 weeks, supported gametocytogenesis in vitro and subsequent gametogenesis in Anopheles stephensi mosquitoes. Using data from 11 SMFAs and RBCs from 4 separate donors with 3 donors re-tested following various periods of cryo-preservation, we show that overall levels of sporogony in the mosquito, as measured by oocyst prevalence and burdens in the midguts and sporozoites in salivary glands, were similar or better than using ≤1-week old refrigerated RBCs. Additionally, the potential for cryo-preserved RBCs to serve as a universal substrate for SMFAs is shown for a Cambodian isolate of P. falciparum.ConclusionsConsidering the suitability of cryo-preserved RBCs for P. falciparum SMFAs, we suggest guidelines for their use and how they can be integrated into an existing laboratory/insectary framework with the potential to significantly reduce running costs and provide greater reliability. Finally, we discuss scenarios where cryo-preserved RBCs may be especially useful in enhancing our understanding and/or providing novel insights into the patterns and process underlying human-to-mosquito transmission.

scholarly journals A pyrethroïd-treated bed net increases host attractiveness for Anopheles gambiae s.s. carrying the kdr allele in a dual-choice olfactometer

2016 ◽  
Author(s):  
Angélique Porciani ◽  
Malal Diop ◽  
Nicolas Moiroux ◽  
Tatiana Kadoke-Lambi ◽  
Anna Cohuet ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Sub Saharan Africa ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Anopheles Gambiae S.S ◽  
Host Seeking ◽  
Seeking Behavior ◽  
Sub Saharan ◽  
The Impact

AbstractThe use of long lasting insecticide nets (LLINs) treated with pyrethroïd is known for its major contribution in malaria control. However, LLINs are suspected to induce behavioral changes in malaria vectors, which may in turn drastically affect their efficacy against Plasmodium sp. transmission. In sub Saharan Africa, where malaria imposes the heaviest burden, the main malaria vectors are widely resistant to pyrethroïds, the insecticide family used on LLINs, which also threatens LLIN efficiency. There is therefore a crucial need for deciphering how insecticide-impregnated materials might affect the host-seeking behavior of malaria vectors in regards to insecticide resistance. In this study, we explored the impact of permethrin-impregnated net on the host attractiveness for Anopheles gambiae mosquitoes, either susceptible to insecticides, or carrying the insecticide resistance conferring allele kdr. Groups of female mosquitoes were released in a dual-choice olfactometer and their movements towards an attractive odor source (a rabbit) protected by insecticide-treated (ITN) or untreated nets (UTN) were monitored. Kdr homozygous mosquitoes, resistant to insecticides, were more attracted by a host behind an ITN than an UTN, while the presence of insecticide on the net did not affect the choice of susceptible mosquitoes. These results suggest that permethrin-impregnated net is detectable by malaria vectors and that the kdr mutation impacts their response to a LLIN protected host. We discuss the implication of these results for malaria vector control.

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