Abstract
Simple SummaryAedes aegypti and Ae. albopictus are the most important mosquito vectors of dengue, chikungunya and Zika virus. There is growing interest in the control of these vectors using the sterile insect technique in which large numbers of sterilized males are released and compete with wild fertile males for mates. Females that mate with sterile males do not produce viable offspring. A study was performed on the population fluctuations of Ae. aegypti and Ae. albopictus using egg traps in two rural villages with a history of dengue in Chiapas, southern Mexico. Higher numbers of Aedes eggs were recorded in Hidalgo village compared with the village of Río Florido. In contrast, higher number of eggs were collected in areas surrounding Río Florido, compared with those around Hidalgo. Aedes aegypti was the dominant species during the dry season and at the start of the rainy season in both villages. Aedes albopictus populations were lower for most of the dry season, but increased during the rainy season and became dominant at the end of the rainy season in both villages. Aedes albopictus was also the dominant species in the zones of natural vegetation surrounding both villages. We conclude that the efficacy of a program of vector control involving the sterile insect technique could be evaluated in future studies on the isolated mosquito populations in these rural villages, in combination with habitat elimination and appropriate treatment of water sources.Indoor and outdoor ovitraps were placed in 15 randomly selected houses in two rural villages in Chiapas, southern Mexico. In addition, ovitraps were placed in five transects surrounding each village, with three traps per transect, one at the edge, one at 50 m, and another at 100 m from the edge of the village. All traps were inspected weekly. A transect with eight traps along a road between the two villages was also included. Population fluctuations of Aedes aegypti and Ae. albopictus were examined during 2016–2018 by counting egg numbers. A higher number of Aedes spp. eggs was recorded at Hidalgo village with 257,712 eggs (60.9%), of which 58.1% were present in outdoor ovitraps and 41.9% in indoor ovitraps, compared with 165,623 eggs (39.1%) collected in the village of Río Florido, 49.0% in outdoor and 51.0% in indoor ovitraps. A total of 84,047 eggs was collected from ovitraps placed along transects around Río Florido, compared to 67,542 eggs recorded from transects around Hidalgo. Fluctuations in egg counts were associated with annual variation in precipitation, with 2.3 to 3.2-fold more eggs collected from ovitraps placed in houses and 4.8 to 5.1-fold more eggs in ovitraps from the surrounding transects during the rainy season than in the dry season, respectively. Aedes aegypti was the dominant species during the dry season and at the start of the rainy season in both villages. Aedes albopictus populations were lower for most of the dry season, but increased during the rainy season and predominated at the end of the rainy season in both villages. Aedes albopictus was also the dominant species in the zones surrounding both villages. The numbers of eggs collected from intradomiciliary ovitraps were strongly correlated with the numbers of eggs in peridomiciliary ovitraps in both Río Florido (R2adj = 0.92) and Hidalgo (R2adj = 0.94), suggesting that peridomiciliary sampling could provide an accurate estimate of intradomiciliary oviposition by Aedes spp. in future studies in these villages. We conclude that the feasibility of sterile insect technique (SIT)-based program of vector control could be evaluated in the isolated Ae. aegypti populations in the rural villages of our baseline study.
Highlights
Aedes aegypti and Ae. albopictus are the most important insect vectors of human diseases in tropical urban habitats across the world [1]
Mean air temperature in the area surrounding each village was similar or slightly lower than temperatures measured in each village, whereas mean relative humidity was ~15% higher in the area surrounding Río Florido compared to the inhabited zone and was similar in both inhabited and surrounding zones of Hidalgo
We suggest that the persistence of the Ae. aegypti population in Hidalgo during both the dry and rainy seasons may be related to the abundance of household trash abandoned in this village, and the presence of water tanks without larvivorous fish or larvicidal granules, which likely favored oviposition by this species
Summary
Aedes aegypti and Ae. albopictus are the most important insect vectors of human diseases in tropical urban habitats across the world [1]. The Asian tiger mosquito, Ae. Albopictus, can transmit 26 species of arboviruses, including dengue virus [6], it is considered to be a vector of secondary importance in semi-urban habitats in the Americas [3,6,7]. Between the late 19th and early 20th century, this species was implicated as the vector of yellow fever and was the target of an eradication program in Mexico [9,10]. This was successful, and Mexico was certified by the Pan American Sanitary Bureau as free of Ae. aegypti in 1963 (Novo, 1995). In 1965, it re-infested Mexico through the northern border, and in the late 1970s, it was found at the southern border [11], when it was associated with the resurgence of dengue virus in this region [12,13]
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