The larva of Eubasilissa maclachlani White 1862 (Trichoptera: Phryganeidae) from Thailand, with notes on its biology

The final-instar larva of Eubasilissa maclachlani White 1862 is described with illustrations for the first time based on Thai specimens. The larva of E. maclachlani exhibits typical morphological characteristics of Phryganeidae. The morphological characteristics of the larva of E. maclachlani can be seen in the following features: First, the band on the frontoclypeus is anchor-like. Second, the ventral apotome is narrowly triangular. Third, the mesonotum is large and membranous, and the mesonotal sa1 sclerites are contiguous mesally. Fourth, comb-like spines, each consisting of tiny points, are distributed over much of the ventromesal surfaces of the fore- and midcoxae. Finally, the shape of tergite IX is heart-like with reddish brown dots. Larvae of E. maclachlani construct cylindrical cases made from many pieces of plant fragments, fastened together by silk in a ring-like pattern, with five successive rings. The larval habitat and phenology are also briefly discussed.

The unusual genus Ramiheithrus (Trichoptera: Philorheithridae)

The descriptions of males of the two described species of Ramiheithrus (R. virgatus Neboiss and R. kocinus Neboiss) are expanded using additional material. The female, pupa and larva of Ramiheithrus virgatus are described for the first time for the genus. Preliminary genetic barcoding analysis suggests the presence of additional undescribed species that are only known as larvae. The unusual larval habitat is described and issues relating to this are discussed.

Oviposition of Culicoides insignis (Diptera: Ceratopogonidae) under laboratory conditions with notes on the developmental life history traits of its immature stages

Background Culicoides insignis is a confirmed vector of bluetongue virus (BTV) throughout the American tropics and a possible vector of epizootic hemorrhagic disease virus (EHDV) in Florida. Despite its importance, fundamental information on the biology and ecology of this vector species is lacking. In this study, we examined the oviposition of C. insignis under laboratory conditions, monitored the development of immature stages and attempted colonization of this species. Methods Live C. insignis females were collected from the field using CDC-UV-LED traps, allowed to blood-feed on live chicken and given various natural substrates for oviposition in two-choice assays. The eggs deposited were transferred to 0.3% agar slants, and the hatched larvae were provided a diet of Panagrellus redivivus Linnaeus nematodes and the development of all immature stages was monitored. Results Culicoides insignis females exhibited an overall oviposition preference for dishes containing mud from their larval habitat as gravid females deposited a significantly higher number of eggs on these dishes (35.3 eggs/female) than on controls (17.7 eggs/female). The ovipositing females also deposited a higher percentage of eggs on substrates with habitat mud and other organically enriched muds (≥ 75.2%) compared to controls (31.0%). The larvae developed successfully to adulthood on the nematode diet, exhibiting high overall larval survival rates (85.0%). Sex ratios of the F1 generation were male biased, approximately 3:1 (male:female). Captive mating could not be induced in the F1 adults. Conclusions Mud from the larval habitat and other organically enriched muds provide strong oviposition cues to C. insignis under laboratory conditions. Further studies will be needed to identify the key biotic/abiotic factors influencing midge oviposition in the field. The agar/nematode method is effective for the rearing of C. insignis larvae. However, further studies will be needed to address the issue of male-biased sex ratios in the progeny and to examine the mating habits/cues of C. insignis in nature, which may provide clues towards inducing captive mating in the F1 adults. Graphical abstract

Australian mosquito assemblages vary between ground and sub-canopy habitats

Background The surveillance and control of mosquito-borne diseases is dependent upon understanding the bionomics and distribution of the vectors. Most studies of mosquito assemblages describe species abundance, richness and composition close to the ground defined often by only one sampling method. In this study, we assessed Australian mosquito species near the ground and in the sub-canopy using two traps baited with a variety of lures. Methods Mosquitoes were sampled using a 4 × 4 Latin square design at the Cattana Wetlands, Australia from February to April 2020, using passive box traps with octenol and carbon dioxide and three variations of a sticky net trap (unbaited, and baited with octenol or octenol and carbon dioxide). The traps were deployed at two different heights: ground level (≤ 1 m above the ground) and sub-canopy level (6 m above the ground). Results In total, 27 mosquito species were identified across the ground and sub-canopy levels from the different traps. The abundance of mosquitoes at the ground level was twofold greater than at the sub-canopy level. While the species richness at ground and sub-canopy levels was not significantly different, species abundance varied by the collection height. Conclusions The composition of mosquito population assemblages was correlated with the trap types and heights at which they were deployed. Coquillettidia species, which prefer feeding on birds, were mainly found in the sub-canopy whereas Anopheles farauti, Aedes vigilax and Mansonia uniformis, which have a preference for feeding on large mammals, were predominantly found near the ground. In addition to trap height, environmental factors and mosquito bionomic characteristics (e.g. larval habitat, resting behaviour and host blood preferences) may explain the vertical distribution of mosquitoes. This information is useful to better understand how vectors may acquire and transmit pathogens to hosts living at different heights. Graphical abstract

Tracking Microbial Communities Across Aedes Albopictus Life Stages and Larval Habitat Types

Aedes albopictus, the Tiger Mosquito, has been hailed as one of the most invasive arbovirus-transmitting mosquitoes globally. With the growing potential of microbial methods for mosquito control, it has become increasingly imperative to understand the factors that contribute to naturally-occurring microbiome communities. Here, we analyzed the impact of larval water type and life stage on the microbial community of Aedes albopictus. The field-collected water samples from tree holes and tires that were used to rear larval mosquitoes in the laboratory were significantly different from each other in terms of sOTU (bacterial species) richness, with tree holes having a far greater number of sOTUs. For beta diversity measures (Bray-Curtis dissimilarity) Aedes albopictus were not significantly different from adult Aedes aegypti, but mosquito sex, life stage, and overall treatment group were significantly different when analyzed by ANOSIM. Based on our findings, the environment surrounding larval mosquitoes (and subsequent adult mosquitoes from those habitats) and the life stage of mosquitoes (regardless of species) shapes mosquito microbiome assemblages. This work further supports the idea that mosquito adults maintain a microbiome specific to larval habitat, despite major reductions to their microbiome prior to eclosion, which could shape the success of implemented microbial engineering or control methods.

Fauna and Larval Habitat Characteristics of Mosquitoes (Diptera: Culicidae) in Kashan County, Central Iran, 2019

Background: Mosquitoes are responsible for spreading devastating parasites and pathogens causing some important infectious diseases. The present study was done to better understand and update the fauna of Culicidae and to find out the distribution and the type of their larval habitats in Kashan County. Methods: This study was done in four districts of Kashan County (Central, Qamasr, Niasar and Barzok). Mosquito lar-vae were collected from 23 active larval habitats using a standard 350ml capacity mosquito dipper from April to late December 2019. The collected larvae were transferred to containers containing lactophenol, and after two weeks indi-vidually mounted in Berlese's fluid on a microscope slide and identified to species by morphological characters and valid keys. Results: In this study, a total of 9789 larvae were collected from urban and rural areas in Kashan County. The identified genera were Anopheles, Culiseta and Culex. In this study larvae of An. turkhudi, Cx. perexiguus, Cx. mimeticus, Cx. deserticola and Cs. subochrea were collected for the first time from Kashan County. Conclusion: The results of this study indicate the presence and activity of different mosquito species in Kashan County that some of them are vectors of arbovirus and other vector-borne diseases.

Impact of underground storm drain systems on larval ecology of Culex and Aedes species in urban environments of Southern California

An extensive network of storm water conveyance systems in urban areas, often referred to as the “underground storm drain system” (USDS), serves as significant production habitats for mosquitoes. Knowledge of whether USDS habitats are suitable for newly introduced dengue vectors Aedes aegypti and Ae. albopictus will help guide surveillance and control efforts. To determine whether the USDS functions as a suitable larval habitat for Culex, Ae. aegypti and Ae. albopictus in southern California, we examined mosquito habitat utilization and larval survivorship using laboratory microcosm studies. The data showed that USDS constituted 4.1% of sampled larval habitats for Ae. aegypti and Ae. albopictus, and 22.0% for Cx. quinquefasciatus. Furthermore, USDS water collected in the summer completely inhibited Aedes larval development, but yielded a 15.0% pupation rate for Cx. quinquefasciatus. Food supplementation in the microcosms suggests that nutrient deficiency, toxins and other factors in the USDS water led to low success or complete failure of larval development. These results suggest that USDS habitats are currently not major productive larval habitats for Aedes mosquitoes in southern California. Our findings prompt inclusion of assessments of pupal productivity in USDS habitats and adult mosquito resting sites in the mosquito surveillance program.

Oviposition and Larval Development of Culicoides Insignis Lutz (Diptera: Ceratopogonidae) under Laboratory Conditions

BackgroundCulicoides insignis Lutz (Diptera: Ceratopogonidae) is a confirmed vector of bluetongue virus (BTV) throughout the American tropics and a possible vector of epizootic hemorrhagic disease virus (EHDV) in Florida. Despite its importance, fundamental information on the biology and ecology of this species is lacking. In this study, we examined the oviposition and larval development of C. insignis under laboratory conditions and attempted colonization of this species. MethodsLive C. insignis females were collected from the field using CDC-UV-LED traps, allowed to blood-feed on live chicken, and given various natural substrates for oviposition in two-choice assays. The eggs deposited were transferred to 0.3% agar slants and the hatched larvae were provided a diet of Panagrellus redivivus Linnaeus nematodes. ResultsCulicoides insignis females exhibited an overall oviposition preference for dishes containing mud from their larval habitat as gravid females deposited a significantly higher number of eggs on these dishes (35.3 eggs/female) than on deionized water (DI) substrates (17.7eggs/female). The ovipositing females also deposited a higher percentage of eggs on substrates with habitat mud and other organically enriched muds (≥ 75.2%) compared to DI substrates (31.0%). The larvae developed successfully to adulthood on the nematode diet, exhibiting high overall larval survival rates (85.0%). Sex-ratios of the F1 generation were male biased ~3:1 (M:F). Captive mating could not be induced in the F1 adults. ConclusionsMud from the larval habitat and other organically enriched muds provide strong oviposition cues to C. insignis. Further studies will be needed to examine whether these cues are olfactory/tactile in nature. Further studies will also be needed to characterize the larval habitat of C. insignis and identify the key biotic/abiotic factors influencing midge oviposition in the field. This information, in the long term, can be potentially exploited to discourage the oviposition of C. insignis in local habitats. The agar/nematode method is effective for the rearing of C. insignis larvae. However, further studies will be needed to address the issue of male-biased sex-ratios in the progeny. Further studies will also be needed to examine the mating habits/cues of C. insignis in nature, which may provide clues towards inducing captive mating in the F1 adults.

The application of drones for mosquito larval habitat identification in rural environments: a practical approach for malaria control?

Background Spatio-temporal trends in mosquito-borne diseases are driven by the locations and seasonality of larval habitat. One method of disease control is to decrease the mosquito population by modifying larval habitat, known as larval source management (LSM). In malaria control, LSM is currently considered impractical in rural areas due to perceived difficulties in identifying target areas. High resolution drone mapping is being considered as a practical solution to address this barrier. In this paper, the authors’ experiences of drone-led larval habitat identification in Malawi were used to assess the feasibility of this approach. Methods Drone mapping and larval surveys were conducted in Kasungu district, Malawi between 2018 and 2020. Water bodies and aquatic vegetation were identified in the imagery using manual methods and geographical object-based image analysis (GeoOBIA) and the performances of the classifications were compared. Further, observations were documented on the practical aspects of capturing drone imagery for informing malaria control including cost, time, computing, and skills requirements. Larval sampling sites were characterized by biotic factors visible in drone imagery and generalized linear mixed models were used to determine their association with larval presence. Results Imagery covering an area of 8.9 km2 across eight sites was captured. Larval habitat characteristics were successfully identified using GeoOBIA on images captured by a standard camera (median accuracy = 98%) with no notable improvement observed after incorporating data from a near-infrared sensor. This approach however required greater processing time and technical skills compared to manual identification. Larval samples captured from 326 sites confirmed that drone-captured characteristics, including aquatic vegetation presence and type, were significantly associated with larval presence. Conclusions This study demonstrates the potential for drone-acquired imagery to support mosquito larval habitat identification in rural, malaria-endemic areas, although technical challenges were identified which may hinder the scale up of this approach. Potential solutions have however been identified, including strengthening linkages with the flourishing drone industry in countries such as Malawi. Further consultations are therefore needed between experts in the fields of drones, image analysis and vector control are needed to develop more detailed guidance on how this technology can be most effectively exploited in malaria control.