In a study carried out in the waterlogged canals that run through Thiruvananthapuram, a team of researchers found that residue released into the water from plastic waste unravels a chemical environment that facilitates the full life cycle of mosquitoes in rapid succession that that of water devoid of plastic waste. .
The study was carried out by RV Ayana Gayathri and DA Evans attached to the Department of Zoology, University College Thiruvananthapuram.
The study highlighted that bisphenol A, bisphenol S and phthalates are identified as the main residues released to water from plastic waste.
“Quantitative estimation of bisphenol A (BPA) by gas chromatography and mass spectroscopy revealed that water samples from mosquito breeding sites possess the compound at a concentration of 1 mg/L (1 ppm). At this concentration, BPA can shorten the life cycle of mosquitoes from 13 days to 10 days,” the study notes.
The life cycle of mosquito ends in polluted water and has four stages such as egg, larva, pupa and adult mosquito. Female mosquitoes lay eggs four days after the blood meal on the water surface or on floating wet objects.
The study observed that under the atmospheric temperature range of 26 to 31 degrees, the eggs hatch into larvae after 36 hours.
Technically, the study found that in the presence of BPA, hatching time is reduced to 18 hours.
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Mosquito-borne diseases such as malaria, dengue fever, encephalitis, chikungunya and Kyasanur forest disease are major health concerns for people living in tropical countries.
The globe’s equator offers plenty of chances for mosquitoes to survive with heavy rainfall, high humidity, and high temperatures. Therefore, the mosquito population density is high in these regions compared to temperate regions.
Anthropogenic factors such as the disposal of plastic waste provide additional chances for mosquitoes to complete their life cycle, as this waste creates stagnation.
Thus, the present study found that instead of providing additional chances of survival, the residue released to water from plastic waste unravels a chemical environment that facilitates the full life cycle of mosquitoes in rapid succession relative to that of water devoid of plastic waste.
“During the peak of summer, the atmospheric temperature is high in the range of 30 to 38 degrees Celsius, while the life cycle of mosquitoes is completed in 12 days, which is further shortened to 9 days by BPA. Mosquitoes typically complete two life cycles within a month, and the presence of BPA in their breeding sites may facilitate the completion of the life cycle within 30 days,” the study notes.
They said this could have far-reaching implications for the mosquito threat and that humans act as facilitators.