Insect-eating worms get buzzy killing mosquito vectors of human lethal diseases

 

A new study published in Biocontrol Science and Technology this week suggests that beneficial nematodes could form a novel approach to halting the spread of diseases such as dengue, yellow fever, chikungunya and the Zika virus via the Aedes aegypti mosquito.

Leading biopesticide technology company Bionema has published data from a study exploring the use of beneficial nematodes in the control of Aedes aegypti – the mosquito responsible for spreading diseases such as dengue, yellow fever, chikungunya and the Zika virus to nearly 100 million people per year.

In the study, four species of insect-eating nematodes were introduced to Aedes aegypti mosquito eggs in vitro, and mosquito larval mortality was recorded as a primary outcome. All nematodes showed some efficacy, but the species Heterorhabditis bacteriophora was identified as the most virulent in killing the mosquito larvae. Larval mortality was dose-dependent, with a higher and more rapid death rate caused by higher nematode concentrations. The nematodes could be seen within dead mosquito larvae within two days of their introduction.

This is an important study because it provides evidence that beneficial nematodes could offer an effective, natural, biological approach to controlling mosquito vectors of human diseases.

The World Health Organization’s (WHO’s) Integrated Vector Management program currently includes various strategies, which aim to prevent mosquito breeding by improving water storage and solid waste disposal, or to use toxic chemical insecticides to eradicate breeding sites and destroy adult mosquitoes. However, these strategies have not yet eliminated mosquito populations, and the continuous use of toxic chemicals has resulted in the development of chemical resistance in many countries, while raising concerns about additional risks to human health and environmental pollution.

Therefore, there remains an important gap in our ability to prevent infection by mosquito vectors. This is a gap that urgently needs closing because, according to the WHO, mosquito bites result in the deaths of more than 1 million people every year.

Dr Minshad Ansari, Founder and CEO of Bionema, said “Diseases such as dengue, yellow fever, chikungunya and the Zika virus are causing significant morbidity and mortality every year, and WHO reports that pesticides – such as those used to control these diseases – are themselves responsible for up to 20,000 lethal poisonings every year. We in the bioprotection community are committed to finding a way to control the insects that spread these diseases, while protecting people from toxic poisons, at the same time. Biological agents – such as beneficial nematodes – might be one approach to achieving this goal, although we obviously need to investigate this particular solution further before it can be used commercially against mosquitos.”

The current study suggests that beneficial nematodes have potential for development into a novel, non-toxic and effective strategy for Aedes aegypti control. If proven effective in a real-world situation, and if it can be up-scaled for commercialization, this type of approach could be added to the WHO’s current Integrated Vector Management program, where biocontrol agents could make a significant, targeted impact on lethal mosquito populations.