Anopheles gambiae attraction to floral and human-skin-based odours and their combination is modulated by previous bloodmeal experience

Abstract Background: Mosquitoes use odours to find energy resources, blood hosts and oviposition sites. These odour sources are normally spatio-temporally segregated in a mosquito’s life history. This study was carried out to determine the attractiveness of Anopheles gambiae to flower- and human-mimicking synthetic volatiles.Methods: This study was carried out in Muheza District in northeast of Tanzania. Anopheles gambiae s.s. Kisumu strain was used in all experiments. The chemicals/odour blends used were Vectrax, skin lure and the combination thereof. The attractiveness of Vectrax and Skin Lure were compared to each other in an insectary and semi-field settings. Semi-field experiments were then conducted using mosquito-spheres. In the two settings, parous or non-parous female mosquitoes, were simultaneously offered four treatments: Skin Lure, Vectrax, a combination of the two, and a control (no attractant). Results: In the insectary nulliparous and parous mosquitoes preferred skin odours and combinations thereof over floral odours. However, in semi-field settings significantly more nulliparous mosquitoes more caught with floral odours, whereas no differences were observed for parous females. Combining floral and human volatiles did not augment attractiveness.Conclusions: Nulliparous and parous An. gambiae s.s. are attracted to combinations of odours derived from floral and human volatiles. However, combinations of floral and skin odours did not augment attraction in semi-field settings, in spite of the fact that these blends activate distinct sets of sensory neurons. Instead, mosquito preference appeared to be modulated by blood meal experience from floral to a more generic attraction to odour blends. Results are discussed both from an odour coding, as well as from an application perspective.

Download Full-text

Is Anopheles gambiae attraction to floral and human skin-based odours and their combination modulated by previous blood meal experience?

10.21203/rs.3.rs-33608/v3 ◽

2020 ◽

Author(s):

ELISON ELIEZA KEMIBALA ◽

Agenor Mafra-Neto ◽

Jesse Saroli ◽

Rodrigo Silva ◽

Anitha Philbert ◽

...

Keyword(s):

Life History ◽

Anopheles Gambiae ◽

Human Skin ◽

Sensory Neurons ◽

Blood Meal ◽

Olfactory Receptors ◽

Developmental State ◽

Sensu Stricto ◽

Monitoring And Control ◽

Activation Patterns

Abstract BackgroundMosquitoes use odours to find energy resources, blood hosts and oviposition sites. While these odour sources are normally spatio-temporally segregated in a mosquito’s life history, here this study explored to what extent a combination of flower- and human-mimicking synthetic volatiles would attract the malaria vector Anopheles gambiae sensu stricto (s.s.)MethodsIn the laboratory and in large (80 m2) outdoor cages in Tanzania, nulliparous and parous An. gambiae s.s. were offered choices between a blend of human skin volatiles (Skin Lure), a blend of floral volatiles (Vectrax), or a combination thereof. The blends consisted of odours that induce distinct, non-overlapping activation patterns in the olfactory circuitry, in sensory neurons expressing olfactory receptors (ORs) and ionotropic receptors (IRs), respectively. Catches were compared between treatments.ResultsIn the laboratory nulliparous and parous mosquitoes preferred skin odours and combinations thereof over floral odours. However, in semi-field settings nulliparous were significantly more caught with floral odours, whereas no differences were observed for parous females. Combining floral and human volatiles did not augment attractiveness.ConclusionsNulliparous and parous An. gambiae s.s. are attracted to combinations of odours derived from spatio-temporally segregated resources in mosquito life-history (floral and human volatiles). This is favourable as mosquito populations are comprised of individuals whose nutritional and developmental state steer them to diverging odours sources, baits that attract irrespective of mosquito status could enhance overall effectiveness and use in monitoring and control. However, combinations of floral and skin odours did not augment attraction in semi-field settings, in spite of the fact that these blends activate distinct sets of sensory neurons. Instead, mosquito preference appeared to be modulated by blood meal experience from floral to a more generic attraction to odour blends. Results are discussed both from an odour coding, as well as from an application perspective.

Download Full-text

Anopheles Gambiae s.s Attraction to Floral and Human-Skin-Based Odors and Their Combination is Modulated by Previous Bloodmeal Experience

10.21203/rs.3.rs-33608/v1 ◽

2020 ◽

Author(s):

ELISON ELIEZA KEMIBALA ◽

Agenor Mafra-Neto2 ◽

Jesse Saroli ◽

Rodrigo Silva ◽

Anitha Philbert ◽

...

Keyword(s):

Life History ◽

Anopheles Gambiae ◽

Human Skin ◽

Sensory Neurons ◽

Olfactory Receptors ◽

Developmental State ◽

Monitoring And Control ◽

Anopheles Gambiae S.S ◽

Odor Coding ◽

Activation Patterns

Abstract Background: Mosquitoes use odors in finding energy resources, blood hosts and oviposition sites. While these odor sources are normally spatio-temporally segregated in a mosquito’s life history, here we explored to what extent a combination of flower- and human-mimicking synthetic volatiles would attract the malaria vector Anopheles gambiae s.s.Methodology: In the laboratory and in large (80 m2) outdoor cages in Tanzania, nulliparous and parous Anopheles gambiae s.s. were offered choices between a blend of human skin volatiles (Skin Lure), a blend of floral volatiles (Vectrax), or a combination thereof. The blends consisted of odors that induce distinct, non-overlapping activation patterns in the olfactory circuitry, in sensory neurons expressing olfactory receptors (ORs) and ionotropic receptors (IRs), respectively. Catches were compared between treatments. Results: In the laboratory nulliparous and parous mosquitoes preferred skin odors and combinations thereof over floral odors. However, in semi-field settings nulliparous were significantly more caught with floral odors, whereas no differences were observed for parous females. Combining floral and human volatiles did not augment attractiveness.Conclusions: Nulliparous and parous An. gambiae s.s. are attracted to combinations of odors derived from spatio-temporally segregated resources in mosquito life-history (floral and human volatiles). This is favourable as mosquito populations are comprised of individuals whose nutritional and developmental state steer them to diverging odors sources, baits that attract irrespective of mosquito status could enhance overall effectiveness and use in monitoring and control. However, combinations of floral and skin odors did not augment attraction in semi-field settings, in spite of the fact that these blends activate distinct sets of sensory neurons. Instead, mosquito preference appeared to be modulated by blood meal experience from floral to a more generic attraction to odor blends. Results are discussed both from an odor coding, as well as from an application perspective.

Download Full-text

Is Anopheles gambiae attraction to floral and human skin-based odours and their combination modulated by previous blood meal experience?

Malaria Journal ◽

10.1186/s12936-020-03395-2 ◽

2020 ◽

Vol 19 (1) ◽

Author(s):

Elison E. Kemibala ◽

Agenor Mafra-Neto ◽

Jesse Saroli ◽

Rodrigo Silva ◽

Anitha Philbert ◽

...

Keyword(s):

Anopheles Gambiae ◽

Human Skin ◽

Blood Meal

Download Full-text

Insights into factors sustaining persistence of high malaria transmission in forested areas of sub-Saharan Africa: the case of Mvoua, South Cameroon

Parasites & Vectors ◽

10.1186/s13071-020-04525-0 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Dominique Mieguim Ngninpogni ◽

Cyrille Ndo ◽

Patrick Ntonga Akono ◽

Anicet Nguemo ◽

Amine Nguepi ◽

...

Keyword(s):

Anopheles Gambiae ◽

Malaria Transmission ◽

Anopheles Funestus ◽

Mortality Rates ◽

Molecular Techniques ◽

Sub Saharan Africa ◽

World Health ◽

Enzyme Linked Immunosorbent Assay ◽

Pyrethroid Insecticides ◽

Kisumu Strain

Abstract Background In Mvoua, a village situated in a forested area of Cameroon, recent studies have reported high prevalence of Plasmodium falciparum infection among the population. In order to understand factors that can sustain such a high malaria transmission, we investigated the biology of Anopheles vectors and its susceptibility to insecticides, as well as long-lasting insecticidal net (LLIN) coverage, use and bio-efficacy. Methods A longitudinal entomological survey was conducted from July 2018 to April 2019. Adult mosquitoes were collected using the human landing catch (HLC) method and identified using morphological and molecular techniques. Anopheles gambiae (s.l.) larvae were sampled from several stagnant water pools throughout the village and reared to generate F1 adults. The presence of P. falciparum circumsporozoite antigen was detected in the heads and thoraces of mosquitoes collected as adults using an enzyme-linked immunosorbent assay. The insecticide susceptibility status of the local An. gambiae (s.l.) F1 population to the pyrethroid insecticides deltamethrin 0.5% and permethrin 0.75% was determined using World Health Organization-tube bioassays, while the frequency of the knockdown resistance (kdr) mutation was determined by PCR. Coverage, use and physical integrity of LLINs were assessed in households, then cone assays were used to test for their bio-efficacy on both the reference insecticide-susceptible Kisumu strain and on field F1 An. gambiae (s.l.) Results In total, 110 Anopheles mosquitoes were collected, of which 59.1% were identified as Anopheles funestus (s.l.), 38.18% as An. gambiae (s.l.) and 2.72% as An. ziemanii. Anopheles funestus was the most abundant species except in the long rainy season, when An. gambiae (s.l.) predominated (65.8%). In the dry seasons, vectors were principally endophagous (76% of those collected indoors) while they tended to be exophagous (66% of those collected outdoors) in rainy seasons. High Plasmodium infection was observed in An. gambiae (s.l.) and An. funestus, with a circumsporozoitic rate of 14.29 and 10.77%, respectively. Anopheles gambiae (s.l.) was highly resistant to pyrethroid insecticides (mortality rates: 32% for permethrin and 5% for deltamethrin) and harbored the kdr-L1014F mutation at a high frequency (89.74%). Of the 80 households surveyed, only 47.69% had achieved universal coverage with LLNs. Around 70% of the LLINs sampled were in poor physical condition, with a proportionate hole index > 300. Of the ten LLNs tested, eight were effective against the An. gambiae reference insecticide-susceptible Kisumu strain, showing mortality rate of > 80%, while none of these LLINs were efficient against local An. gamabie (s.l.) populations (mortality rates < 11.5%). Conclusion A combination of elevated P. falciparum infection in Anopheles vector populations, insufficient coverage and loss of effectiveness of LLINs due to physical degradation, as well as high resistance to pyrethroid insecticides is responsible for the persistence of high malaria transmission in forested rural area of Mvoua, Cameroon.

Download Full-text

A field study of competition and interaction between Lemna minor and Lemna trisulca

Canadian Journal of Botany ◽

10.1139/b89-373 ◽

1989 ◽

Vol 67 (10) ◽

pp. 2904-2911 ◽

Cited By ~ 9

Author(s):

Alexander L. McIlraith ◽

Gordon G. C. Robinson ◽

Jennifer M. Shay

Keyword(s):

Life History ◽

Field Study ◽

Key Words ◽

Field Experiments ◽

Lemna Minor ◽

Survey Methods ◽

The Other ◽

Transplant Experiment ◽

Replacement Series ◽

Vegetative Biomass

Field experiments and survey methods were used to assess competition and interaction between Lemna minor L. and Lemna trisulca L. at Delta Marsh, Manitoba. Sites were dominated by one or the other species or codominated by both. Replacement series experiments predicted codominance of L. minor and L. trisulca in an unshaded eutrophic site but predicted L. minor dominance when run for a longer time. Similar experiments conducted in a shaded eutrophic site predicted L. minor dominance. Addition series experiments showed that intraspecific and interspecific competition occurred in the unshaded site. In a eutrophic unshaded ditch, high densities of L. minor suppressed L. trisulca. In a eutrophic shaded site, high densities of L. minor and green algae inhibited L. trisulca, and in a sunny, less eutrophic site high density of each species inhibited the other. In a transplant experiment, L. minor biomass in shaded enclosures approached that found naturally in two shaded sites. Lemna trisulca persisted when shaded. Vegetative biomass trends in an unshaded eutrophic marsh ditch indicated spring and fall L. trisulca dominance and summer L. minor dominance. Shaded eutrophic sites were dominated by L. minor, whereas a less eutrophic site was dominated by L. trisulca. A model is developed to explain dominance patterns, and seasonal life-history responses are considered. Key words: Lemna, duckweed, competition, interaction, resources, light, nutrients.

Download Full-text

The influence of multi-stage predation on population growth and the distribution of the pond-breeding salamander, Ambystoma jeffersonianum

Canadian Journal of Zoology ◽

10.1139/z06-015 ◽

2006 ◽

Vol 84 (3) ◽

pp. 449-458 ◽

Cited By ~ 9

Author(s):

M J Rubbo ◽

K Shea ◽

J M Kiesecker

Keyword(s):

Life History ◽

Population Growth ◽

Field Experiments ◽

Predation Pressure ◽

Field Surveys ◽

Life History Stages ◽

Ambystoma Jeffersonianum ◽

Multi Stage ◽

Fundamental Goal ◽

Distributional Patterns

Understanding the drivers of distributional patterns is a fundamental goal of ecology. For many organisms, distributions are determined by the habitats in which breeding occurs. Therefore, determining the factors that limit post-ovipositional success in specific habitats is critical to deciphering the factors that shape distributions. Using field surveys and laboratory, mesocosm, and field experiments, we conducted a study of the breeding effort of the salamander Ambystoma jeffersonianum (Green, 1827) in sites of varying predation pressure and the susceptibility of its embryos and larvae to predators. We then used these data to parameterize a matrix model examining the effects of predation on population growth. We found that A. jeffersonianum egg masses were less abundant in ponds with higher predation pressure. Moreover, A. jeffersonianum performance was negatively affected by both embryonic and larval predators. The results of the model suggest that only predation acting upon multiple life-history stages can limit population growth for A. jeffersonianum. These data provide support for the hypothesis that multi-stage predation can shape breeding distributions by imposing strong selective costs in specific environments. Furthermore, these data highlight the importance of conducting multi-stage studies and utilizing multiple ecological methodologies when addressing the factors that limit the distribution and abundance of organisms.

Download Full-text

20-Hydroxyecdysone Primes Innate Immune Responses That Limit Bacterial and Malarial Parasite Survival in Anopheles gambiae

mSphere ◽

10.1128/msphere.00983-19 ◽

2020 ◽

Vol 5 (2) ◽

Cited By ~ 5

Author(s):

Rebekah A. Reynolds ◽

Hyeogsun Kwon ◽

Ryan C. Smith

Keyword(s):

Immune Function ◽

Anopheles Gambiae ◽

Blood Meal ◽

Egg Production ◽

Blood Feeding ◽

Innate Immune ◽

Content Type ◽

Innate Immune Function ◽

Cellular Immune Function ◽

Cellular Immune

ABSTRACT Blood feeding is an integral behavior of mosquitoes to acquire nutritional resources needed for reproduction. This requirement also enables mosquitoes to serve as efficient vectors to acquire and potentially transmit a multitude of mosquito-borne diseases, most notably malaria. Recent studies suggest that mosquito immunity is stimulated following a blood meal, independent of infection status. Since blood feeding promotes production of the hormone 20-hydroxyecdysone (20E), we hypothesized that 20E plays an important role in priming the immune response for pathogen challenge. Here, we examine the immunological effects of priming Anopheles gambiae with 20E prior to pathogen infection, demonstrating a significant reduction in bacteria and Plasmodium berghei survival in the mosquito host. Transcriptome sequencing (RNA-seq) analysis following 20E treatment identifies several known 20E-regulated genes, as well as several immune genes with previously reported function in antipathogen defense. Together, these data demonstrate that 20E influences cellular immune function and antipathogen immunity following mosquito blood feeding, arguing the importance of hormones in the regulation of mosquito innate immune function. IMPORTANCE Blood feeding is required to provide nutrients for mosquito egg production and serves as a mechanism to acquire and transmit pathogens. Shortly after a blood meal is taken, there is a peak in the production of 20-hydroxyecdysone (20E), a mosquito hormone that initiates physiological changes, including yolk protein production and mating refractoriness. Here, we examine additional roles of 20E in the regulation of mosquito immunity, demonstrating that priming the immune system with 20E increases mosquito resistance to pathogens. We identify differentially expressed genes in response to 20E treatment, including several involved in innate immune function as well as lipid metabolism and transport. Together, these data argue that 20E stimulates mosquito cellular immune function and innate immunity shortly after blood feeding.

Download Full-text

582 Differentiation of human skin-derived precursors (SKPs) into functional sensory neurons

Journal of Investigative Dermatology ◽

10.1016/j.jid.2019.07.586 ◽

2019 ◽

Vol 139 (9) ◽

pp. S315

Author(s):

A. Bataille ◽

R. Leschiera ◽

N. Le Goux ◽

O. Mignen ◽

C. Brun ◽

...

Keyword(s):

Human Skin ◽

Sensory Neurons

Download Full-text

The life history of a tropical dragonfly: Cora marina (Odonata: Polythoridae) in Guanacaste, Costa Rica

Journal of Tropical Ecology ◽

10.1017/s0266467400009792 ◽

1996 ◽

Vol 12 (4) ◽

pp. 573-581 ◽

Cited By ~ 11

Author(s):

Gordon Pritchard

Keyword(s):

Life History ◽

Costa Rica ◽

Hyporheic Zone ◽

Flight Period ◽

Low Oxygen ◽

Wet Season ◽

Oxygen Conditions ◽

History Of ◽

One Year ◽

Oviposition Sites

ABSTRACTThe life history of Cora marina was followed for one year in two permanent streams at 600 m elevation in Guanacaste National Park; Costa Rica. The water temperature was c. 21°C year-round, but there was a distinct wet-dry seasonality, very little rain falling from January to May. In both streams, C. marina was univoltine. Adults first appeared at the beginning of May and the flight period coincided with the wet season. The availability of water-soaked logs as oviposition sites probably restricts reproduction to the wet season. Eggs hatched from mid-July to December. Recruitment to subsequent larval instars was slow during the wet season but increased at the start of the dry season. Final-instar larvae were collected from March to October. Oviposition in logs above the stream and the ability to live in the low oxygen conditions of the hyporheic zone probably allow eggs and small larvae to survive wet season spates.El ciclo biológico de una libelula tropical: Cora marina (Odonata: Polythoridae) en Guanacaste, Costa Rica.

Download Full-text