Bionomy of Mosquitoes in Bamboo Internodes in an Atlantic Forest Remnant of the State of Rio De Janeiro, Brazil

ABSTRACT Living bamboo stalks are one of the most specialized habitats for mosquito oviposition and immature development. Most of the mosquito species that breed in these habitats are sylvatic, and some are of importance for public health as possible vectors of pathogens. Perforated internodes are a very specialized environment due to the difficulty of access. Furthermore, due to their relatively simple fauna, they represent a valuable model for ecological studies that may be applicable to more complex environments. This study aims to assess the mosquito bionomics of species raised in bamboo internodes. Therefore, the diversity of mosquito species and the influence of abiotic variables (pH and temperature) on the distribution of mosquitoes that breed in this habitat were analyzed. The study area is a fragment of Atlantic Forest within the Association of da Armada (ATA) in Nova Iguaçu, state of Rio de Janeiro, Brazil. Immature mosquitoes were sampled with suction tubes (mouth aspirators) between August 2017 and July 2018. A total of 3,170 larvae were collected in 5 bamboo plants, each with 8 stalks perforated. Of these, 688 larvae reached the adult stage, representing 10 genera and 19 species. The most common species were Culex neglectus (43%), Trichoprosopon digitatum (22%), Culex iridescens (8%), Sabethes identicus (7%), and Orthopodomyia albicosta (7%). The richness of the immatures collected in the ATA was 19 species, with a diversity of 1.10 and Shannon evenness of 0.57. A diverse composition of Culicidae in bamboo stalks was found, although dominance was low.

Fish-Released Kairomones Affect Mosquito Oviposition and Larval Life History

Several species of mosquitoes respond to the presence of kairomones released by larvivorous predators during oviposition habitat selection and larval development. These responses may differ among mosquito species and do not always correlate with larval survival. This study examined the responses of the mosquito Culiseta longiareolata Macquart (Diptera: Culicidae) to kairomones released by three species of fish, Gambusia affinis (Cyprinodontiformes: Poeciliidae), Aphanius mento (Cyprinodontiformes: Cyprinodontidae) and Garra rufa (Cypriniformes: Cyprinidae) during oviposition. In addition, the study examined the effects of kairomones released by Gm. affinis on larval development and survival. Results show that ovipositing female avoided cues from the two larvivorous fish species but not the algivorous Gr. rufa. In addition, developing larvae metamorphosed slower and showed increased mortality when exposed to fish-released kairomones. Culiseta longiareolata larvae are known as dominant competitors, and the straightforward responses of both larvae and adult female to fish-released kairomones may be explained by the lack of additional sources of larval stress other than the presence of predators.

Microorganisms Associated with Mosquito Oviposition Sites: Implications for Habitat Selection and Insect Life Histories

Mosquitoes are considered one of the most important threats worldwide due to their ability to vector pathogens. They are responsible for the transmission of major pathogens such as malaria, dengue, zika, or chikungunya. Due to the lack of treatments or prophylaxis against many of the transmitted pathogens and an increasing prevalence of mosquito resistance to insecticides and drugs available, alternative strategies are now being explored. Some of these involve the use of microorganisms as promising agent to limit the fitness of mosquitoes, attract or repel them, and decrease the replication and transmission of pathogenic agents. In recent years, the importance of microorganisms colonizing the habitat of mosquitoes has particularly been investigated since they appeared to play major roles in their development and diseases transmission. In this issue, we will synthesize researches investigating how microorganisms present within water habitats may influence breeding site selection and oviposition strategies of gravid mosquito females. We will also highlight the impact of such microbes on the fate of females’ progeny during their immature stages with a specific focus on egg hatching, development rate, and larvae or pupae survival.

Screening and Identification of the Botanical Attractant From a Chinese Tea for Aedes Albopictus Oviposition

Background: The use of oviposition attractants is a promising approach to control populations of mosquito vectors at the source; however, the knowledge on oviposition stimulation in Aedes albopictus is very limited. In recent years, tea bags have been proven to attract Aedes aegypti to lay eggs, but the sources of tea are wide and varied; moreover, the factors and mechanisms in tea bags that attract mosquitoes remain unclear.Methods: The effects of three kinds of Chinese tea, nonfermented, fully fermented and postfermented, were comparatively evaluated for their ability to attract mosquito oviposition at dose of 5g/L, 1.5g/L and 0.5g/L, respectively. The attractants in the Liu-pao tea infusion were isolated with gas chromatography–mass spectrometry (GC-MS).Results: Among the three types of fermented teas, the Guangxi Liu-pao tea infusion was a successful oviposition attractant for Ae. albopictus at all the dose tested, and the average OAIs of 5 g/L Liu-pao tea soaked for 7 d and 14 d were 0.73 and 0.67, respectively. Further, in one month of soaking 0.5g/L Liu-Pao tea, the average oviposition activity indexes (OAIs) for Ae.aegypti of soaking for 21 d and 28 d were 0.89 and 0.63, respectively. Functional analyses showed that the compound cedrol at 1 mg/L tested for Ae. albopictus, the average OAI was 0.38.Conclusion: Liu-pao tea can effectively attract Ae. albopictus to lay eggs, and cedrol is one of the ingredients attracting Aedes mosquitoes to lay eggs. These results shed light on the development of Aedes mosquito oviposition attractants and will help to develop innovative monitoring and prevention strategies for Aedes-borne diseases.

Microorganisms Associated With Mosquito Oviposition Sites: Implications for Habitat Selection and Insect Life Histories

Mosquitoes are considered one of the most important threats worldwide due to their ability to vector pathogens. They are responsible for the transmission of major pathogens such as Malaria, dengue, Zika or Chikungunya. Due to the lack of treatments or prophylaxis against many of the transmitted pathogens and an increasing prevalence of mosquito resistance to insecticides and drugs available, alternative strategies are now being explored. Some of these involve the use of microorganisms as promising agent to limit the fitness of mosquitoes, attract or repel them and decrease the replication and transmission of pathogenic agents. In recent years, the importance of microorganisms colonizing the habitat of mosquitoes has particularly been investigated since they appeared to play major roles in their development and diseases transmission. In this issue we will synthesize researches investigating how microorganisms present within water habitats may influence breeding site selection and oviposition strategy of gravid mosquito females. We will also highlight the impact, effect of such microbes on the fate of females’ progeny during their immature stages with a specific focus on egg hatching, development rate and larvae of pupae survival.

Habitat Aedes aegypti dan Aedes albopictus sebagai Vektor Potensial Demam Berdarah Dengue di Kecamatan Ranomeeto Barat, Provinsi Sulawesi Tenggara

Dengue hemorrhagic fever (DHF) is still a problem in some countries, resulting in 390 millioninfections a year in the world. DHF vaccine has not found so the treatment is focused on vector controls.Entomological data describing the bio ecology of vectors in the region can help vector control diseases moreeffectively. The study aims at assessing distribution, characteristic and risk factors in the habitat of Aedes larvain the DHF endemic region of West Ranomeeto subdistrict of Southeast Sulawesi province. This study is ananalytic observational study with a sectional study approach. Data collection was carried out using singlelarva method in 600 houses by purposive sampling. Data analysis uses chi square’s descriptive analysis andlogistics multinomial regression. The result shows larva density in Sindangkasih higher than Jati Bali. Ae.aegypti dominated in Sindangkasih and Ae. albopictus dominated in Jati Bali. Buckets, dispenser tray,refrigerator tray, container made of cements and plastics and container with volume <1 L and 20-100 L arerisk factors affected the exixtence of larvae in Sindangkasih (p<0.05). Plastic containers and dark-coloredcontainer are risk factors that influence the larva’s existence in Jati Bali (p<0.05). Differences in charateristicsof the larvae affect mosquito oviposition in Sindangkasih and Jati Bali. Therefore, it is important to monitorvector populations dynamic and breeding mosquito to prevent outbreak.Keywords: Ae. aegypti, Ae. albopictus, , Sindangkasih, Jati Bali, larval habitat

Oviposition Behavior of Culex tarsalis (Diptera: Culicidae) Responding to Semiochemicals Associated with the Western Mosquitofish, Gambusia affinis (Cyprinodontiformes: Poecilliidae)

Considerable previous research has focused on predator-associated semiochemicals and how they affect mosquito oviposition behavior. However, most of this work has been done without taking into consideration either the natural density of the predators or how other semiochemicals in aquatic environments might affect the responses of gravid mosquitoes. The influence of mosquitofish density, source water (tap vs pond), presence of freshly laid egg rafts, and removal of a putative source of semiochemicals (bacteria) on oviposition by Culex tarsalis Coquillett (Diptera: Culicidae) was studied in laboratory bioassays. Culex tarsalis females were deterred from laying egg rafts on water that contained semiochemicals associated with Gambusia affinis (Baird & Girard), but this deterrence was not strongly associated with the density of fish used to condition aged tap water. The number of egg rafts laid onto Gambusia-exudate water made with either tap water (density &lt; 1 fish per liter) or pond water was typically ≥ 50% of that onto water that did not house mosquitofish. Gravid mosquitoes tested individually did not reduce oviposition onto Gambusia-exudate water as compared to controls. Likewise, oviposition by females with ablated wings did not differ significantly between Gambusia-exudate water and controls. Oviposition onto filter-sterilized Gambusia-exudate water was reduced relative to unfiltered water, suggesting that semiochemicals deterring egg-laying were still present after bacteria were removed. Taken together, these findings suggest that the responses of gravid Cx. tarsalis to chemicals from habitats containing mosquitofish are complex and the origin of the semiochemicals present in the Gambusia-exudate water needs to be elucidated.