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

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.

Exposure of Primate Reservoir Hosts to Mosquito Vectors in Malaysian Borneo

Several vector-borne pathogens of primates have potential for human spillover. An example is the simian malaria Plasmodium knowlesi which is now a major public health problem in Malaysia. Characterization of exposure to mosquito vectors is essential for assessment of the force of infection within wild simian populations, however few methods exist to do so. Here we demonstrate the use of thermal imaging and mosquito magnet independence traps (MMIT) to assess the abundance, diversity and infection rates in mosquitoes host seeking near long-tailed macaque (Macaca fasicularis) sleeping sites in the Lower Kinabatangan Wildlife Sanctuary, Malaysian Borneo. The primary Plasmodium knowlesi vector, Anopheles balabacensis, was trapped at higher abundance near sleeping sites than control trees. Although none of the An. balabacensis collected (n = 15) were positive for P. knowlesi by PCR screening, two were infected with another simian malaria Plasmodium inui. Analysis of macaque stools from sleeping sites confirmed a high prevalence of Plasmodium infection, suspected to be P. inui. Recently, natural transmission of P. inui has been detected in humans and An. cracens in Peninsular Malaysia. The presence of P. inui in An. balabacensis here and previously in human-biting collections highlight its potential for spillover from macaques to humans in Sabah. We advocate the use of MMITs for non-invasive sampling of mosquito vectors that host seek on wild simian populations.

Evaluation of Methods to Collect Diurnal Culicidae (Diptera) at Canopy and Ground Strata, in the Atlantic Forest Biome

Hand-held insect nets are the standard method for capturing vector mosquitoes of sylvatic arboviruses; however, occupational risks and biases due to individual skill and attractiveness are important limitations. The use of chemical attractants and automatic traps could be an alternative to resolve these limitations. This study compares the yields achieved using nets with those employing electrical traps with CO2 and BG-Lure®, near the ground and in the canopy strata (6.0 and 8.0 m high). The study was conducted at the Cantareira State Park, which is in the Brazilian Atlantic Forest biome. In the 18 collections performed, 3570 specimens of 52 taxa were obtained. The most frequent species captured near the ground were Wyeomyia confusa and Limatus durhamii, whereas Sabethes albiprivus, Sabethes purpureus, and Haemagogus leucocelaenus were the most frequent in the canopy. The nets resulted in greater species richness and abundance, followed by the trap employing CO2. The combination of CO2 traps with BG-Lure® did not improve performance. The use of BG-Lure® alone resulted in low abundance and a low number of species. Our results demonstrate that the use of traps with CO2 can be complementary to collections with nets; however, for species of epidemiological interest such as those of the genera Haemagogus and Sabethes, especially in the canopy, the net remains the method of choice.

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.

Comparison of climatic factors on mosquito abundance at US Army Garrison Humphreys, Republic of Korea

Introduction

A number of studies have been conducted on the relationship between the distribution of mosquito abundance and meteorological variables. However, few studies have specifically provided specific ranges of temperatures for estimating the maximum abundance of mosquitoes as an empirical basis for climatic dynamics for estimating mosquito-borne infectious disease risks.

Methods

Adult mosquitoes were collected for three consecutive nights/week using Mosquito Magnet® Independence® model traps during 2018 and 2019 at US Army Garrison (USAG) Humphreys, Pyeongtaek, Gyeonggi Province, Republic of Korea (ROK). An estimate of daily mean temperatures (provided by the Korea Meteorological Administration) were distributed at the maximum abundance for selected species of mosquitoes using daily mosquito collection data after controlling for mosquito ecological cycles and environmental factors.

Results

Using the Monte-Carlo simulation, the overall mosquito population abundance peaked at 22.7°C (2.5^th—97.5^th: 21.7°C–23.8°C). Aedes albopictus, vector of Zika, chikungunya, dengue fever and other viruses, abundance peaked at 24.6°C (2.5^th–97.5^th, 22.3°C–25.6°C), while Japanese encephalitis virus (JEV) vectors, e.g., Culex tritaeniorhynchus and Culex pipiens, peaked at 24.3°C (2.5^th–97.5^th: 21.9°C–26.3°C) and 22.6°C (2.5^th–97.5^th: 21.9°C–25.2°C), respectively. Members of the Anopheles Hyrcanus Group, some of which are vivax malaria vectors in the ROK, abundance peaked at 22.4°C (2.5^th–97.5^th: 21.5°C–23.8°C).

Conclusion

The empirical mean temperature ranges for maximum abundance were determined for each mosquito species collected at USAG Humphreys. These data contributed to the identification of relative mosquito abundance patterns for estimating mosquito-borne disease risks and developing and implementing disease prevention practices.

Effectiveness of mosquito magnets for reducing mosquito (Diptera) populations in coastal areas of Samut Songkhram province, Thailand

OBJECTIVE

The aim of this research is to study the effectiveness of mosquito magnet (MM) for reducing mosquitoes (Diptera) populations in coastal areas.

MATERIALS AND METHODS

The study sites are in the coastal area of Samut Songkhram province, Thailand, which is divided into two locations; one that is 2 km and another that is 4 km in distance from the sea. We used the Mosquito Magnet® Independence (MMI) trap for effective field testing in Samut Songkhram Province, Thailand. Traps were placed 100 m away from the house (one trap per location) and mosquitoes were collected at night from 6 PM to 6 AM during September and October 2017 (30 days).

RESULTS

A total of 2,561 adult mosquitoes, including Anopheles epiroticus Linton & Harbach, Culex quinquefasciatus Say, Cx. sitiens Wiedmann, and Cx. gelidus Theobald were collected by MMI. At a 2-km distance from the sea were captured more mosquitoes per night more than at a 4-km distance (63.63 ± 42.30 vs. 21.70 ± 12.42). The comparison of effectiveness of MMI in two locations of the coastal area was shown to have a statistically significant difference (p < 0.05) and analysis of the correlation between the number of mosquitoes caught in coastal areas, including at a 2- and 4-km distance from the sea, accounting for weather factors, we found that the effectiveness of MMI was not correlated with weather (p > 0.05).

CONCLUSION

Overall, this study demonstrated that MM can be used to control mosquitoes in coastal areas with high efficiency, especially 2 km away from the sea.

Is Dengue Vector Control Deficient in Effectiveness or Evidence?: Systematic Review and Meta-analysis

BACKGROUND

Although a vaccine could be available as early as 2016, vector control remains the primary approach used to prevent dengue, the most common and widespread arbovirus of humans worldwide. We reviewed the evidence for effectiveness of vector control methods in reducing its transmission.

METHODOLOGY/PRINCIPAL FINDINGS

Studies of any design published since 1980 were included if they evaluated method(s) targeting Aedes aegypti or Ae. albopictus for at least 3 months. Primary outcome was dengue incidence. Following Cochrane and PRISMA Group guidelines, database searches yielded 960 reports, and 41 were eligible for inclusion, with 19 providing data for meta-analysis. Study duration ranged from 5 months to 10 years. Studies evaluating multiple tools/approaches (23 records) were more common than single methods, while environmental management was the most common method (19 studies). Only 9/41 reports were randomized controlled trials (RCTs). Two out of 19 studies evaluating dengue incidence were RCTs, and neither reported any statistically significant impact. No RCTs evaluated effectiveness of insecticide space-spraying (fogging) against dengue. Based on meta-analyses, house screening significantly reduced dengue risk, OR 0.22 (95% CI 0.05-0.93, p = 0.04), as did combining community-based environmental management and water container covers, OR 0.22 (95% CI 0.15-0.32, p<0.0001). Indoor residual spraying (IRS) did not impact significantly on infection risk (OR 0.67; 95% CI 0.22-2.11; p = 0.50). Skin repellents, insecticide-treated bed nets or traps had no effect (p>0.5), but insecticide aerosols (OR 2.03; 95% CI 1.44-2.86) and mosquito coils (OR 1.44; 95% CI 1.09-1.91) were associated with higher dengue risk (p = 0.01). Although 23/41 studies examined the impact of insecticide-based tools, only 9 evaluated the insecticide susceptibility status of the target vector population during the study.

CONCLUSIONS/SIGNIFICANCE

This review and meta-analysis demonstrate the remarkable paucity of reliable evidence for the effectiveness of any dengue vector control method. Standardised studies of higher quality to evaluate and compare methods must be prioritised to optimise cost-effective dengue prevention.