A green approach
“If you do what you did, you’ll get what you got”
Whilst the search for new, safe, and environmentally friendly insecticides continues it remains a fact that prolonged use of insecticides always leads to resistance. Time and again Einstein’s quote is spot on: “If you do what you did, you’ll get what you got”.
But scientific research has also delivered solutions that do not suffer from the problem of resistance. The biological insecticide Bacillus thuringiensis israelensis (Bti) is a bacterium that is highly specific for mosquitoes and black flies (that transmit river blindness in West Africa) and has been used in many places around the world over the last three decades.
Approved by the US Environmental Protection Agency
Bti is approved by the US Environmental Protection Agency (EPA), and is completely harmless to humans and other non-target organisms. Bti is used against larvae before they emerge as adult mosquitoes from breeding sites. Numerous field evaluations have been published, and limited field trials have been conducted in (sub)tropical settings. All reported success.
Although not yet at a stage where it can be used on an operational scale, we also support the development of fungi against adult mosquitoes. Fungi, like Beauveria bassiana, are excellent in killing adult mosquitoes, with minimal chance of resistance developing because of the multiple attack modes. This minimises the risk of mutants becoming resistant.
Surely mosquitoes have a role in nature. What happens when we eliminate them?
This is a valid point. Mosquitoes form part of the food chain and occur at the bottom of the pyramid. If we remove them, then higher species depending on them for survival can switch to other food sources. Unless they are specialist feeders. To date, however, science has not identified such specialist predators. In the aquatic stage, mosquito larvae do serve as a food source for many other organisms (e.g. fish) and in some parts of the world their overall biomass is critical in sustaining an environmental equilibrium.
However, disease vectors like the African malaria mosquito Anopheles gambiae s.l. or the dengue mosquito Aedes aegypti occupy small breeding sites in which the biodiversity is absolutely minimal. Removal of larvae from such small sites will have minimal impact on the ecosystem. Adult mosquitoes play a (minor) role in pollination of plants, and may serve as a food source to predators like dragonflies and bats. However, a study on bats in Germany pointed out that mosquitoes form only a minimal proportion of their diet.
Invasive and not part of the indigenous fauna
For some mosquitoes the story is different. The dengue mosquito Aedes aegypti originates from Africa and was accidentally transported to the Caribbean and North America during the slave trade era. The Asian tiger mosquito, Aedes albopictus, travels around the world in container shipments of used tires or Lucky Bamboo plants. These species are invasive and do not form a part of the indigenous fauna of the places where they arrive and settle. Dengue is a major problem in the Caribbean today, and it is transmitted by mosquitoes that don’t belong there in the first place. Avian malaria on the Galapagos islands is causing havoc amongst local and unique bird species but is transmitted by Culex quinquefasciatus that arrived there through human activity from Ecuador. In such cases we are resolute: remove them completely and relentlessly.
At Soper Strategies, we see larval control and larval source management as major components of vector and mosquito-borne disease elimination programmes.
Not just because it can be done in a green and environmentally benign manner but also since larval control can be seamlessly integrated with other control strategies such as indoor residual spraying (IRS) or bednets (LLINs).
Overall, we highly value the environment and proceed with as little impact as possible. ‘Green’ is a key value within our company. That’s logical in the world we live in today.