Long-Range But Not Short-Range Attraction of Male Aedes aegypti (Diptera: Culicidae) Mosquitoes to Humans

Female Aedes aegypti (Linnaeus) mosquitoes integrate multiple sensory cues to locate human hosts for blood meals. Although male Ae. aegypti swarm around and land on humans in nature to mate, direct evidence of attraction to humans is limited. Male mosquito attraction to human host cues is often undetectable in confined laboratory assays, leading to a misconception that male mosquitoes are not attracted to humans. We used semifield experiments to demonstrate robust attraction of male Ae. aegypti to humans. Human-baited traps captured up to 25% of released males within 15 min, whereas control traps without humans as bait failed to capture males. Rapid attraction to humans was further demonstrated through videography. Males swarmed around and landed on human subjects, with no activity recorded in paired unbaited controls. Finally, we confirm the lack of discernible male attraction to humans in small laboratory cages. Our experiments demonstrate that both male and female Ae. aegypti show attraction to humans, but with clear sex-specific behavioral differences at short-range. Male mosquito attraction to humans is likely to be important for mating success in wild populations and its basis should be further explored. Our results highlight the importance of arena size and assay design for mosquito behavioral research. A better understanding of host cues that attract males could help us to improve mosquito surveillance and control.

Eave and swarm collections prove effective for biased captures of male Anopheles gambiae mosquitoes in Uganda

Background Traditional malaria vector sampling techniques bias collections towards female mosquitoes. Comprehensive understanding of vector dynamics requires balanced vector sampling of both males and females. Male mosquito sampling is also necessary for population size estimations by male-based mark-release-recapture (MRR) studies and for developing innovations in mosquito control, such as the male-targeted sterile insect technique and other genetic modification approaches. This study evaluated a range of collection methods which show promise in providing a more equal, or even male-biased, sex representation in the sample. Results Swarms were found at all study sites and were more abundant and larger at the peak of the wet season. Swarm sampling caught the most males, but when man/hour effort was factored in, sampling of eaves by aspiration was the more efficient method and also provided a representative sample of females. Grass-roofed houses were the most productive for eave collections. Overall few mosquitoes were caught with artificial resting traps (clay pots and buckets), although these sampling methods performed better at the start of the wet season than at its peak, possibly because of changes in mosquito ecology and an increased availability of natural resting sites later in the season. Aspiration of bushes was more productive at the peak of the wet season than at the start. Conclusions The results of this study demonstrate that eave aspiration was an efficient and useful male mosquito collection method at the study sites and a potentially powerful aid for swarm location and MRR studies. The methods evaluated may together deliver more sex-balanced mosquito captures and can be used in various combinations depending on the aims and ecological parameters of a given study.

Strong attraction of male mosquitoes (Aedes aegypti) to humans

Female Aedes aegypti mosquitoes integrate multiple sensory cues to locate human hosts for blood meals. While male mosquitoes do not blood feed, male Ae. aegypti swarm around and land on humans in nature. Basrur et al. (2020) generated male Aedes aegypti lacking the fruitless gene and discovered that they gained strong attraction to humans, similar to female mosquitoes. The authors assume that host-seeking is a female-specific trait, which they confirmed through experiments. However, all experiments were performed under confined laboratory conditions which appear to inhibit swarming behavior. We used semi-field experiments to demonstrate robust attraction of male Ae. aegypti to humans. Human-baited traps captured up to 25% of released males within 15 min, whereas control traps without humans as bait failed to capture males. Rapid attraction to humans was further demonstrated through videography. Males swarmed around and landed on human subjects, with no activity recorded in paired unbaited controls. The absence of female Ae. aegypti in these experiments rules out a hypothesis by Basrur et al. (2020) that males are attracted not to the human, but to host-seeking females near humans. Finally, we confirm the lack of male attraction to humans in small laboratory cages, even when using recently field-collected males. Our direct observations of male mosquito attraction to humans refute a key assumption of Basrur et al. (2020) and raise questions around conditions under which fruitless prevents male host-seeking. Male mosquito attraction to humans is likely to be important for mating success in wild populations and its basis should be further explored.

Modeling the potential of wAu-Wolbachia strain invasion in mosquitoes to control Aedes-borne arboviral infections

Arboviral infections such as dengue, Zika and chikungunya are fast spreading diseases that pose significant health problems globally. In order to control these infections, an intracellular bacterium called Wolbachia has been introduced into wild-type mosquito populations in the hopes of replacing the vector transmitting agent, Aedes aegypti with one that is incapable of transmission. In this study, we developed a Wolbachia transmission model for the novel wAu strain which possesses several favourable traits (e.g., enhanced viral blockage and maintenance at higher temperature) but not cyctoplasmic incompatibility (CI)—when a Wolbachia-infected male mosquito mates with an uninfected female mosquito, producing no viable offspring. This model describes the competitive dynamics between wAu-Wolbachia-infected and uninfected mosquitoes and the role of imperfect maternal transmission. By analysing the system via computing the basic reproduction number(s) and stability properties, the potential of the wAu strain as a viable strategy to control arboviral infections is established. The results of this work show that enhanced maintenance of Wolbachia infection at higher temperatures can overcome the lack of CI induction to support wAu-Wolbachia infected mosquito invasion. This study will support future arboviral control programs, that rely on the introduction of new Wolbachia variants.

The Influence of Vegetation and House Index on Male Mosquitoes DHF Vector Abundance on Kawengen Sub-District

The environmental conditions of an area can be a major risk factor for potential outbreaks of DHF. Dense areas with a variety of vegetation are facilitated as breeding sites and have an impact on vector density. The high of vector population give an effect the speed of transmission vector-borne diseases. DHF vector population is related to the vector DHF mating pattern. Adult male mosquitoes vector DHF plays an important role in the pattern of mating DHF. The proportion of mating between adult male and females mosquitoes is 1: 1. Thus it can be seen the density of male mosquitoes, it can be easily estimated the number of female mosquitoes which fertilize and lay eggs. Conducted using observational analytics with male mosquito population surveillance approach. This research aimed to effect of vegetation and House Index (HI) on the abundance of male mosquito populations. Adult mosquitoes taken using light traps with a total sampling technique. Using spatial vegetation analysis shows that Kawengen residents, has a variety of monoecious groups and rice fields. Variety of fruit trees (banana,mango,guava,soursop), flower plants (frangipani,hibiscus), bamboo, another plant (i.e teak). Vegetation density is in the low-moderate category. Kawengen included in the category of moderate density (HI=36%). The number of Aedes sp. male mosquitoes trapped by light traps, of the total trapped mosquito was 6.52%. Variety and density of plants give a support the abundance of male mosquitoes. As a resting and feeding place. HI in moderate density category, indicates there is a positive container or a place for laying eggs. The larvae density affects the sex ratio of mosquitoes.

Critical analysis of the mosquito repellency evoked by the 10-34 kHz recorded animal sounds: The case of the African female A. gambiae s.s

Animals sounds have been mimicked in electronic mosquito repellents (EMRs) and exploited as a tool in the control of malaria by targeting the vector, the female Anopheles gambiae s.s. The claimed mosquito repellency of 30.3 % due to Anti-Pic®, an electronic mosquito repellent, had failed to be confirmed in subsequent studies. However, studies on mosquito startle based on initial behavioural activities without an attractant yielded 34.12 % repellency elicited by the 10-34 kHz recorded sound of O. tormota. Other malaria intervention measures involving the use of chemicals have been impeded by the pathogen and vector resistance hence slowing down the rate of decline of malaria morbidity and mortality. The research thus focused on the analytical study of the African female A. gambiae s.s repellency evoked by the 10-34 kHz recorded animal sound of male mosquito, Anopheles gambiae and Delphinapterus leucas. Landing rates and behavioural startle responses of the mated female A. gambiae on food attractant evoked by the individual sound of the male mosquito, A. gambiae, O. tormota and D. leucas were determined and analysed. The male and female A. gambiae were bred and reared under controlled laboratory conditions of 60-80 % humidity, 25±2 °C temperature with equal light-darkness hour cycle in KEMRI, entomology laboratories. Isolation of the male and female mosquitoes from a swarm was based on physical features and affinity to blood meal. The sounds of O. tormota and D. leucas were acquired and the sound of the male A. gambiae were recorded from the Kenya Medical Research Institute (KEMRI) entomology laboratory, Kisumu. The sounds were filtered into 10-34 kHz frequency band and analysed using Avisoft-SAS LAB Pro version 5.2 and Raven Pro 1.5 software. The sound of O. tormota was also studied. A fighto-Y glass cage well designed into control, neutral and treatment chambers was used in the study. Both control and treatment chambers were connected to blood meal maintained at 38.60°C. The treatment cage was also connected to the source of sound and a swarm of 50 female mosquitoes into the neutral cage and observed for 1,200 s. The sounds of the A. gambiae, O. tormota and D. leucas yielded 2.10, 2.20 and 3.00 landings/minute respectively associated with adverse behaviour. The protection index (PI) anchored on the number of mosquitoes that landed, probed and fed on the blood meal in the treatment and neutral cage for the sounds of the A. gambiae, O. tormota and D. leucas was 42.73 %, 40.24 % and 10.64 % respectively. The sound of the A. gambiae was characterised by steady and minimally dipped pulsate acoustic power with wide bandwidth. The protection index achieved by the sound of the male A. gambiae did not differ significantly from the sound of O. tormota (0.1740 > 0.05), though differed significantly from the sound emitted from the Anti-Pic® EMR (p = 5.3440 x 10−5).The author summaryPhilip Amuyunzu Mang’are is a PhD. Physics student in Egerton University. He has authored many papers and books. He is currently a Lecturer of Physics (Electronics), Masinde Muliro University of Science and Technology. He is a member of the Biophysical Society and the current President of Biophysical society (Kenya). Prof. Ndiritu F. Gichuki, is a Professor of Physics Egerton University. Currently he is the Registrar Academic Affairs in Chuka University. His vast experience has seen him supervise many postgraduate students who have taken key positions in the society. Prof. Samwel Rotich is a Profesor of Physics in Moi University specialising in Electronics. He has a wide experience in Physics and Biophysics. He is a registered member of the Biophysical Society and the Patron of Biophysical Society Kenya Chapter. He has published many papers and supervised many postgraduate students. Dr. Makatiani Kubochi is a Lecturer in Moi University with vast experience in entomology. She has published many papers and supervised many postgraduate students. Dr. Rapando Bernard Wakhu is a renown theoretical Physicist with experience in acoustics and Fourier analysis based in Masinde Muliro University of Science and Technology. He has supervised many postgraduate students and published many papers.

The Potency of Polygamy Behavior in Aedes aegypti Mosquitoes by Venereal Transmission Dengue Virus

Male Aedes aegypti mosquito has been considered to not have any important role in transmitting dengue virus (DENV). The purpose of this study is to prove that male Ae. aegypti mosquito does have an important role in transmitting DENV 3 through venereal transmission with their potency of its polygamy behavior. The data collection was done using colonization method and intrathoracal injection. The presence of DENV 3 on male and female mosquitoes was proven by RT-PCR method (profile of DNA band specifically on 511 bp) and serotyping PCR (290 bp). The data were analyzed using univariate analysis followed by bivariate analysis with parametric test ANOVA. The result of the study demonstrated that male Ae. aegypti mosquitoes do have an important role in transmitting DENV 3 through venereal transmission with the potency of their polygamy behavior. There was no significant difference between the polygamy behaviors of Ae. aegypti male mosquito infected by DENV and the non-infectious Ae. aegypti male mosquito.

PLASMODIUM DOMINAN DALAM NYAMUK ANOPHELES BETINA (Anopheles spp.) PADA BEBERAPA TEMPAT DI DISTRIK MANOKWARI BARAT

Malaria contagious by mosquito Anopheles Betina bringing protozoa parasite in its body (Plasmodium). Plasmodium there are four specieses that is Plasmodium vivax, Plasmodium ovale, Plasmodium malariae and Plasmodium falciparum, but often becomes pathogen that is Plasmodium vivax and Plasmodium falciparum. As for intention of this research is to identify Plasmodium which is dominant at female Anopheles mosquito (Anopheles spp.) and knows distribution pattern of female Anopheles mosquito (Anopheles spp.) in some places in Districts Manokwari Barat. Based on research result done to four locations that is area Amban, Wosi, Sanggeng and Kota is found [by] 1024 mosquito tails. From the amounts only 115 mosquito tails was mosquito Anopheles Betina while the other is mosquito Anopheles male, mosquito Culex and Aedes. Mosquito Anopheles Betina found consisted of 4 species that is Anopheles bancrofti, Anopheles kochi, Anopheles farauti and Anopheles koliensis. Mosquito Anopheles Betina which is dissected, obtained 2 the Plasmodium species in mosquito spit gland is Plasmodium vivax and Plasmodium falciparum, and from calculation by index dominant can be told that both types of this very dominant Plasmodium in Districts Manokwari Barat because its the dominant index > 5%.