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FUNGAL BIOPESTICIDES

Saturday, 17th of September 2011

• FUNGAL BIOPESTICIDES

‘transient exposure to clay tiles sprayed with a candidate biopesticide comprising spores of a natural isolate of Beauveria bassiana, could reduce malaria transmission potential to zero within a feeding cycle.’ 

Abstract below; full text at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3163643/?tool=pubmed

 

PLoS One. 2011; 6(8): e23591. Published online 2011 August 29. doi:  10.1371/journal.pone.0023591

PMCID: PMC3163643

Copyright Blanford et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Lethal and Pre-Lethal Effects of a Fungal Biopesticide Contribute to Substantial and Rapid Control of Malaria Vectors

Simon Blanford,1,2 Wangpeng Shi,2,3 Riann Christian,4,5 James H. Marden,6 Lizette L. Koekemoer,4,5 Basil D. Brooke,4,5 Maureen Coetzee,4,5 Andrew F. Read,1,2,7 and Matthew B. Thomas2,5*

1Center for Infectious Disease Dynamics, Mueller Laboratory, Department of Biology, Penn State University, University Park, Pennsylvania, United States of America

2Center for Infectious Disease Dynamics, Merkle Lab, Department of Entomology, Penn State University, University Park, Pennsylvania, United States of America

3Key Laboratory for Biological Control, China Agricultural University, Ministry of Agriculture, Beijing, China

4Vector Control Reference Unit, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa

5Malaria Entomology Research Unit, School of Pathology, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa

6Department of Biology, Mueller Laboratory, Penn State University, University Park, Pennsylvania, United States of America

7Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America

Fabio T. M. Costa, Editor

State University of Campinas, Brazil

* E-mail: mbt13@psu.edu

Conceived and designed the experiments: SB AFR MBT. Performed the experiments: SB WS RC LLK BDB. Analyzed the data: SB. Contributed reagents/materials/analysis tools: JHM MC. Wrote the paper: SB AFR MBT.

Received June 11, 2011; Accepted July 20, 2011.

Abstract

Rapidly emerging insecticide resistance is creating an urgent need for new active ingredients to control the adult mosquitoes that vector malaria. Biopesticides based on the spores of entomopathogenic fungi have shown considerable promise by causing very substantial mortality within 7–14 days of exposure. This mortality will generate excellent malaria control if there is a high likelihood that mosquitoes contact fungi early in their adult lives. However, where contact rates are lower, as might result from poor pesticide coverage, some mosquitoes will contact fungi one or more feeding cycles after they acquire malaria, and so risk transmitting malaria before the fungus kills them. Critics have argued that ‘slow acting’ fungal biopesticides are, therefore, incapable of delivering malaria control in real-world contexts. Here, utilizing standard WHO laboratory protocols, we demonstrate effective action of a biopesticide much faster than previously reported. Specifically, we show that transient exposure to clay tiles sprayed with a candidate biopesticide comprising spores of a natural isolate of Beauveria bassiana, could reduce malaria transmission potential to zero within a feeding cycle. The effect resulted from a combination of high mortality and rapid fungal-induced reduction in feeding and flight capacity. Additionally, multiple insecticide-resistant lines from three key African malaria vector species were completely susceptible to fungus. Thus, fungal biopesticides can block transmission on a par with chemical insecticides, and can achieve this where chemical insecticides have little impact. These results support broadening the current vector control paradigm beyond fast-acting chemical toxins.