Professor Yaw Asare Afrane, a distinguished Medical Entomologist at the Department of Medical Microbiology, University of Ghana Medical School, has issued a cautionary statement regarding the pervasive and sustained use of agricultural pesticides. He asserts that this practice is significantly contributing to the increasing resistance of mosquitoes to insecticides employed in malaria control efforts.
Professor Afrane elucidated that mosquito populations are progressively adapting to the chemicals intended to exterminate them, thereby rendering conventional malaria prevention measures less effective.
“Farmers utilize pesticides or other forms of insecticides to eradicate pests that threaten their crops. However, these substances often wash into nearby water bodies where mosquitoes breed,” he explained. “Consequently, from their immature stages, before reaching adulthood and biting humans, mosquitoes are exposed to these chemicals, leading to the development of tolerance to insecticides.”
This warning was delivered during an inaugural lecture organized by the University of Ghana in Accra, titled “Fighting the Bite: Human Activities and the Changing Landscape of Mosquito-Borne Diseases in Africa.”
Professor Afrane clarified that insecticide resistance occurs when mosquitoes gradually develop biological mechanisms enabling them to withstand chemicals designed to eliminate them. Certain mosquitoes now produce enzymes—substances in living organisms that accelerate chemical reactions—capable of detoxifying insecticides applied in homes or incorporated into treated mosquito nets.
Furthermore, he noted that mosquitoes reproduce rapidly and can develop genetic mutations that allow them to survive repeated insecticide exposure. Some mosquitoes now exhibit “knockdown resistance,” where they appear temporarily incapacitated after insecticide exposure but soon recover.
“All distributed bed nets are treated with insecticide. Nevertheless, mosquitoes are adept and reproduce swiftly, leading to the development of mutations that enable them to evade the insecticides used against them,” he stated.
Professor Afrane also observed that mosquito behavior is evolving due to pressure from control interventions such as insecticide-treated bed nets and cautioned against uncontrolled human activities that create ideal breeding environments for mosquitoes across Ghana and Africa.
His research across various ecological zones in Ghana reveals a strong correlation between mosquito abundance, environmental conditions, and human activities.
Reflecting on earlier research conducted in Kumasi, Professor Afrane highlighted how informal urban agriculture and irrigation systems created favorable conditions for mosquito breeding and malaria transmission. He further noted the influence of deforestation and climate change on mosquito ecology.
He identified stagnant water in discarded car tires, cans, broken buckets, drainage systems, and poorly managed irrigation schemes as primary mosquito breeding sites.
“The mosquitoes breeding around and biting us daily are not originating from forests; they are bred within our own areas, around our homes, and sometimes within the house itself,” he remarked.
He warned that climate change could potentially facilitate the spread of mosquitoes to high-altitude areas of Ghana that previously recorded low mosquito populations.
The entomologist disclosed that his research group has detected invasive mosquito species in Ghana, including Anopheles stephensi, originally from Asia, and Aedes albopictus, known for dengue fever transmission. Plans are underway to control these species.
He mentioned lymphatic filariasis (a parasitic disease transmitted by mosquitoes causing elephantiasis), chikungunya, and the West Nile virus as significant mosquito-borne diseases affecting global populations.
Professor Afrane advocated for collective actions to reduce mosquito breeding sites through enhanced sanitation, environmental management, and proper urban planning.
He called for the reintroduction of stringent environmental sanitation enforcement by local authorities, including town and municipal councils, to address sanitation challenges effectively.
“Human activities have created opportunities for mosquitoes to breed around us, bite us, and cause disease. By reversing these activities, we can eliminate mosquito-borne diseases,” he asserted.
He emphasized the need for increased investment in research, public health planning, and the training of more experts in mosquito control and medical entomology to combat this menace.
Chairing the lecture, Professor Nana Aba Appiah Amfo, Vice-Chancellor of the University of Ghana, stated that mosquito-borne diseases are not merely natural occurrences; they are influenced by urban farming, mining, deforestation, environmental pollution, and inadequate drainage systems.
She noted the timeliness of the lecture, coinciding with the onset of the rainy season in Ghana, which brings flooding, stagnant water, and increased mosquito breeding sites. This underscores the need for improved sanitation, urban planning, and collective environmental responsibility.
Professor Appiah Amfo urged public support for scientific research and emphasized personal responsibility in maintaining clean environments, as mosquito control should not be solely the responsibility of scientists and government agencies.
She commended Professor Afrane for his contributions to research and policy, highlighting that his work has informed malaria control strategies, surveillance systems, and vector control interventions in Ghana and other African countries.
By Benjamin Adamafio Commey, GNA
