Development of Metarhizium anisopliae and Beauveria bassiana formulations for control of malaria mosquito larvae

Abstract

BackgroundThe entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana have demonstrated effectiveness against anopheline larvae in the laboratory. However, utilising these fungi for the control of anopheline larvae under field conditions, relies on development of effective means of application as well as reducing their sensitivity to UV radiation, high temperatures and the inevitable contact with water. This study was conducted to develop formulations that facilitate the application of Metarhizium anisopliae and Beauveria bassiana spores for the control of anopheline larvae, and also improve their persistence under field conditions.MethodsLaboratory bioassays were conducted to test the ability of aqueous (0.1% Tween 80), dry (organic and inorganic) and oil (mineral and synthetic) formulations to facilitate the spread of fungal spores over the water surface and improve the efficacy of formulated spores against anopheline larvae as well as improve spore survival after application. Field bioassays were then carried out to test the efficacy of the most promising formulation under field conditions in western Kenya.ResultsWhen formulated in a synthetic oil (ShellSol T), fungal spores of both Metarhizium anisopliae and Beauveria bassiana were easy to mix and apply to the water surface. This formulation was more effective against anopheline larvae than 0.1% Tween 80, dry powders or mineral oil formulations. ShellSol T also improved the persistence of fungal spores after application to the water. Under field conditions in Kenya, the percentage pupation of An. gambiae was significantly reduced by 39 - 50% by the ShellSol T-formulated Metarhizium anisopliae and Beauveria bassiana spores as compared to the effects of the application of unformulated spores.ConclusionsShellSol T is an effective carrier for fungal spores when targeting anopheline larvae under both laboratory and field conditions. Entomopathogenic fungi formulated with a suitable carrier are a promising tool for control of larval populations of malaria mosquitoes. Additional studies are required to identify the best delivery method (where, when and how) to make use of the entomopathogenic potential of these fungi against anopheline larvae.

The mosquito microbiota influences vector competence for human pathogens

“…The use of microbes as biopesticides does, however, have a precedent for vector control. The entomopathogenic bacteria Bacillus thuringiensis and the fungus Beauveria bassiana have been evaluated in field trials for the control of mosquito larvae [92–94]. B. bassiana not only kills mosquitoes but also reduces susceptibility to DENV infection through immune pathway activation [43].…”

Isolation and efficacy of entomopathogenic fungus (Metarhizium anisopliae) for the control of Aedes albopictus Skuse larvae: suspected dengue vector in Pakistan

“…They have low toxicity to non-target organisms and using entomopathogenic fungus as larvicides may be a promising approach for biological control of mosquitoes [10] due to their selective toxicity and ready decomposability in the ecosystem. Also unlike the inherent dangers which are associated with the process of production of synthetic insecticides, the process for the manufacture of microbial products is safe and less pollutant [11] . The present study has therefore been taken to explore larvicidal activity of fungus isolate in terms of their cost-effective and environment friendly behavior.…”

Estabilidade de conídios de Beauveria bassiana (Bals.) Vuill. acondicionados em diferentes embalagens

“…Na tentativa de solucionar esses problemas, têm-se desenvolvido métodos de secagem para que os conídios de fungos entomopatogênicos possam manter-se viáveis durante longos períodos de armazenamento (Pereira;Roberts, 1991;Hedgecock et al, 1995;Moore et al, 1996, Hong et al, 1997Marques et al, 1999;Smith et al, 1999;Sanyang, 2000;Luz;Batagin, 2005;Bukhari et al, 2011;Ritu, 2012); entretanto, estudos realizados sobre a influência de embalagens em formulações ou em conídios puros desses micro-organismos não estão disponíveis na literatura especializada.…”