Comparison of automatic traps to capture mosquitoes (Diptera: Culicidae) in rural areas in the tropical Atlantic rainforest

Evaluation of Methods for Collecting Mosquitoes (Culicidae: Diptera) in Canopy and Ground Strata in the Brazilian Savanna

The hand-net is the standard method for capturing mosquitoes with sylvatic diurnal activity in disease outbreaks in Brazil. However, occupational risks and biases related to the collectors' abilities and attractiveness are important limitations. In this study, we compared hand-nets with automatic traps (CDC) associated to CO₂ and BG-Lure^® in the Vassununga State Park, a Brazilian Savanna protection area. The collections carried out over 27 days on the ground and the forest canopy. A total of 1555 mosquitoes were obtained in 20 taxa. The diversity index ranged between 1.12 and 1.79 and the dominance index from 0.22 to 0.40. The dominant species on the ground was Aedes scapularis (46.0%), and in the canopy, Hg. janthinomys/capricornii (31.9%). Haemagogus leucocelaenus was rare (n = 2). The hand-net resulted in the greatest diversity and abundance of species in both strata, followed by the traps associated with CO₂. A low degree of similarity was observed between the hand-net on the ground compared to the other capture methods. The use of BG-Lure^® alone resulted in a low number of specimens. In conclusion, the hand-net is still the method of choice for collecting arbovirus vectors in the diurnal period, especially yellow fever vectors.

Modification of the Folmer primers for the cytochrome c oxidase gene facilitates identification of mosquitoes

BACKGROUND

Accurate identification of mosquito species is essential for the development and optimization of strategies to control mosquitoes and mosquito-borne diseases. Problems with the morphological identification of mosquito species have led to the use of molecular identification techniques, in particular the Folmer cytochrome c oxidase subunit I (COI) PCR system (FCOS), originally designed to identify a range of other invertebrates.

METHODS

As there can be difficulties identifying mosquitoes using FCOS, we re-evaluated the FCOS primers and developed a new COI-based SYBR PCR (the Auburn COI system-AUCOS) to improve the molecular identification of mosquitoes. Sequence data in GenBank for 33 species from 10 genera of mosquitoes were used to develop our AUCOS primers. Two molecular assays (AUCOS, FCOS) and morphological identification were carried out on mosquitoes collected from the field in Auburn, Alabama (USA) and on Saint Kitts.

RESULTS

With a convenience sample of individual mosquitoes comprising 19 species from six genera in Saint Kitts (n = 77) and Auburn (n = 48), our AUCOS provided higher-quality sequence data than FCOS. It also proved more sensitive than FCOS, successfully amplifying 67.5% (85/126) as opposed to 16.7% (21/126) of the samples. The species determined by morphology, or genus with damaged samples, matched that as determined by AUCOS for 84.9% (62/73) of the samples. Morphological classification was confirmed by FCOS with 81.0% (17/21) of samples producing utilizable sequences. While both FCOS and AUCOS correctly identified all the Aedes, Anopheles, Deinocerites, and Uranotaenia species in the study, identification of Culex species was less successful with both methods: 50.0% (3/6) by FCOS and 35.7% (5/14) by AUCOS.

CONCLUSIONS

The AUCOS DNA barcoding system for mosquito species described in this study is superior to the existing FCOS for the identification of mosquito species. As AUCOS and FCOS amplify the same variable region of the COI, the large amount of existing data on GenBank can be used to identify mosquito species with sequences produced by either PCR.

Comparison of sand fly trapping approaches for vector surveillance of Leishmania and Bartonella species in ecologically distinct, endemic regions of Peru

BACKGROUND

In Peru, the information regarding sand fly vectors of leishmaniasis and bartonellosis in the Amazon region is limited. In this study, we carried out sand fly collections in Peruvian lowland and highland jungle areas using different trap type configurations and screened them for Leishmania and Bartonella DNA.

METHODOLOGY/PRINCIPAL FINDINGS

Phlebotomine sand flies were collected in Peruvian Amazon jungle and inter Andean regions using CDC light trap, UV and color LED traps, Mosquito Magnet trap, BG Sentinel trap, and a Shannon trap placed outside the houses. Leishmania spp. screening was performed by kDNA PCR and confirmed by a nested cytochrome B gene (cytB) PCR. Bartonella spp. screening was performed by ITS PCR and confirmed by citrate synthase gene (gltA). The PCR amplicons were sequenced to identify Leishmania and Bartonella species. UV and Blue LED traps collected the highest average number of sand flies per hour in low jungle; UV, Mosquito Magnet and Shannon traps in high jungle; and Mosquito Magnet in inter Andean region. Leishmania guyanensis in Lutzomyia carrerai carrerai and L. naiffi in Lu. hirsuta hirsuta were identified based on cytB sequencing. Bartonella spp. related to Bartonella bacilliformis in Lu. whitmani, Lu. nevesi, Lu. hirsuta hirsuta and Lu. sherlocki, and a Bartonella sp. related to Candidatus B. rondoniensis in Lu. nevesi and Lu. maranonensis were identified based on gltA gene sequencing.

CONCLUSIONS/SIGNIFICANCE

UV, Blue LED, Mosquito Magnet and Shannon traps were more efficient than the BG-Sentinel, Green, and Red LED traps. This is the first report of L. naiffi and of two genotypes of Bartonella spp. related to B. bacilliformis and Candidatus B. rondoniensis infecting sand fly species from the Amazon region in Peru.

Phlebotomines (Diptera: Psychodidae) and Mosquitoes (Diptera: Culicidae) Surrounding an Environmental Protection Zone in the Metropolitan Region of Natal: Use of Light-Emitting Diode (LED) Bulbs in Entomological Surveillance

Entomological surveillance is very important for parasite and arbovirus vector control programs. Light traps with incandescent bulbs are used to attract insects and analyze the factors that contribute to the occurrence of species surrounding an environmental protection zone. Phlebotomine and mosquito abundance and their diversity were analyzed. Captures occurred monthly using six CDC light traps with two incandescent bulbs, two blue and two red LED lights. A total of 2211 phlebotomines of seven species and 4486 mosquitoes belonging to 20 taxa were captured. Different phlebotomine and mosquito species were found in the forest and peridomestic environments, with a predominance of the sand fly Evandromyia walkeri (Newstead) and the mosquito Coquillettidia venezuelensis (Theobald). There was a significant difference in the abundance of sand flies captured with the three bulbs tested, the blue bulb being the most efficient. The Shannon-Wiener diversity index showed that the trap equipped with a red LED light obtained a higher value than that of the blue LED and incandescent bulb. Analyses showed that the potential vectors and non-vectors of the two groups circulate between the forest and the peridomestic environment, suggesting an adaptation process of species to the altered environment. An incandescent light bulb can be substituted by an LED bulb, without compromising the sensitivity of the method. A blue LED is indicated for the abundant capture of mosquitoes and sand flies, while a red LED obtains a better result in terms of species diversity per capture.

Culicidae-centric metabarcoding through targeted use of D2 ribosomal DNA primers

A practical limitation to many metabarcoding initiatives is that sampling methods tend to collect many non-target taxa, which become “amplicon noise” that can saturate Next Generation Sequencing results and lead to both financial and resource inefficiencies. An available molecular tool that can significantly decrease these non-target amplicons and decrease the need for pre-DNA-extraction sorting of bycatch is the design of PCR primers tailored to the taxa under investigation. We assessed whether the D2 extension segment of the 28S ribosomal operon can limit this shortcoming within the context of mosquito (Culicidae) monitoring. We designed PCR primers that are fully conserved across mosquitos and exclude from amplification most other taxa likely to be collected with current sampling apparatuses. We show that, given enough sequencing depth, D2 is an effective marker for the detection of mosquito sequences within mock genomic DNA pools. As few as 3,050 quality-filtered Illumina reads were able to recover all 17 species in a bulk pool containing as little as 0.2% of constituent DNA from single taxa. We also mixed these mosquito DNA pools with high concentrations of non-Culicidae bycatch DNA and show that the component mosquito species are generally still recoverable and faithful to their original relative frequencies. Finally, we show that there is little loss of fidelity in abundance parameters when pools from degraded DNA samples were sequenced using the D2 primers.

Revision of the Atratus Group of Culex (Melanoconion) (Diptera: Culicidae)

BACKGROUND

Despite the importance of some species of Culex (Melanoconion) (Diptera: Culicidae) as vectors of several arboviruses that cause diseases in humans and other animals, there are few taxonomic studies focusing on species of the subgenus, especially providing morphological keys for species identification.

RESULTS

Thirteen species of the Atratus Group of Culex (Melanoconion) were reviewed, five new species are described, and two taxonomic changes are proposed: Cx. (Mel.) exedrus Root, 1927 and Cx. (Mel.) loturus Dyar, 1925 are resurrected from synonymy with Cx. (Mel.) dunni Dyar, 1918 and Cx. (Mel.) zeteki Dyar, 1918, respectively. The Atratus Group now includes fourteen species: Cx. (Mel.) atratus Theobald, 1901; Cx. (Mel.) caribeanus Galindo & Blanton, 1954; Cx. (Mel.) columnaris Sá & Hutchings n. sp.; Cx. (Mel.) commevynensis Bonne-Wepster & Bonne, 1919; Cx. (Mel.) comptus Sá & Sallum n. sp.; Cx. (Mel.) dunni; Cx. (Mel.) ensiformis Bonne-Wepster & Bonne, 1919; Cx. (Mel.) exedrus; Cx. (Mel.) longisetosus Sá & Sallum n. sp.; Cx. (Mel.) longistylus Sá & Sallum n. sp.; Cx. (Mel.) loturus; Cx. (Mel.) spinifer Sá & Sallum n. sp.; Cx. (Mel.) trigeminatus Clastrier, 1970; and Cx. (Mel.) zeteki. Keys, descriptions and illustrations for the identification of the male, female, pupal and fourth-instar larval stages of each species are provided. The treatment of each species includes a complete synonymy, descriptions of available life stages, a taxonomic discussion, updated bionomics and geographical distribution, and a list of material examined.

CONCLUSIONS

The taxonomy of the Atratus Group of Culex (Melanoconion) is updated, including descriptions of five new species. The number of valid species is greater than the number recognized in the previous taxonomic study of the group, increasing from seven to 14 species. Distributional and bionomical data are updated. Morphology-based identification keys for females, males, fourth-instar larvae and pupae provided in this study will facilitate species identification.

Effectiveness of Mosquito Magnet® trap in rural areas in the southeastern tropical Atlantic Forest

Traps are widely employed for sampling and monitoring mosquito populations for surveillance, ecological and fauna studies. Considering the importance of assessing other technologies for sampling mosquitoes, we addressed the effectiveness of Mosquito Magnet® Independence (MMI) in comparison with those of the CDC trap with CO2 and Lurex3® (CDC-A) and the CDC light trap (CDC-LT). Field collections were performed in a rural area within the Atlantic Forest biome, southeastern state of São Paulo, Brazil. The MMI sampled 53.84% of the total number of mosquitoes, the CDC-A (26.43%) and CDC-LT (19.73%). Results of the Pearson chi-squared test (χ2) showed a positive association between CDC-LT and species of Culicini and Uranotaeniini tribes. Additionally, our results suggested a positive association between CDC-A and representatives of the Culicini and Aedini tribes, whereas the MMI was positively associated with the Mansoniini and Sabethini as well as with Anophelinae species. The MMI sampled a greater proportion (78.27%) of individuals of Anopheles than either the CDC-LT (0.82%) or the CDC-A traps (20.91%). Results of the present study showed that MMI performed better than CDC-LT or CDC-A in sampling mosquitoes in large numbers, medically important species and assessing diversity parameters in rural southeastern Atlantic Forest.

Effectiveness of mosquito magnet in preserved area on the coastal Atlantic rainforest: implication for entomological surveillance

A variety of traps are used for sampling, surveillance, and monitoring of mosquito vector species associated with parasite and pathogen transmission. Here, we assessed the performance of the Mosquito Magnet Independence trap with Lurex3 (MMI), by comparing its effectiveness with those of a Centers forDisease Control and Prevention light trap (CDC-LT) and CDC with CO2 and Lurex3 (CDC-A) in a dense tropical rainforest. Multivariate generalized linear models revealed significant differences among the traps regarding mosquito composition and abundance (deviance = 768; P = 0.016). Variance analyses indicated that the MMI captured significantly more mosquitoes compared with CDC-LT (P < 0.01) and CDC-A (P < 0.03). The abundance values did not significantly differ between the CDC-LT and CDC-A traps (P = 0.7). Mosquito species richness was higher from the MMI than from the CDC-LT and CDC-A traps. Furthermore, medically important mosquito species captured by the three traps showed high association with MMI. These results suggest the potential to use the MMI in studies aiming to obtain entomological surveillance information about medically important mosquitoes that occur in tropical rainforest areas. The MMI could also be used in faunal studies focusing on increasing knowledge about mosquito diversity. Considering the present positive results, the effectiveness of the MMI should additionally be evaluated in other Brazilian natural ecosystems. Further studies are also needed to address demographic data from the mosquito population sampled by the MMI.