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Ong’wen F, Njoroge MM, Fillinger U, Lutermann H, Bukhari T. Efficacy of Metarhizium anisopliae, Isolate ICIPE 7, against Anopheles arabiensis, Glossina fuscipes, and Rhipicephalus spp. INSECTS 2024; 15:449. [PMID: 38921163 PMCID: PMC11204313 DOI: 10.3390/insects15060449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/08/2024] [Accepted: 05/12/2024] [Indexed: 06/27/2024]
Abstract
Arthropod vectors are responsible for a multitude of human and animal diseases affecting poor communities in sub-Saharan Africa. Their control still relies on chemical agents, despite growing evidence of insecticide resistance and environmental health concerns. Biorational agents, such as the entomopathogenic fungus Metarhizium anisopliae, might be an alternative for vector control. Recently, the M. anisopliae isolate ICIPE 7 has been developed into a commercial product in Kenya for control of ticks on cattle. We were interested in assessing the potential of controlling not only ticks but also disease-transmitting mosquitoes and tsetse flies using cattle as blood hosts, with the aim of developing a product for integrated vector management. Laboratory bioassays were carried out with M. anisopliae, isolate ICIPE 7 and isolate ICIPE 30, to compare efficacy against laboratory-reared Anopheles arabiensis. ICIPE 7 was further tested against wild Glossina fuscipes and Rhipicephalus spp. Dose-response tests were implemented, period of mosquito exposure was evaluated for effects on time to death, and the number of spores attached to exposed vectors was assessed. Exposure to 109 spores/mL of ICIPE 7 for 10 min resulted in a similar mortality of An. arabiensis as exposure to ICIPE 30, albeit at a slower rate (12 vs. 8 days). The same ICIPE 7 concentration also resulted in mortalities of tsetse flies (LT50: 16 days), tick nymphs (LT50: 11 days), and adult ticks (LT50: 20 days). Mosquito mortality was dose-dependent, with decreasing LT50 of 8 days at a concentration of 106 spores/mL to 6 days at 1010 spores/mL. Exposure period did not modulate the outcome, 1 min of exposure still resulted in mortality, and spore attachment to vectors was dose-dependent. The laboratory bioassays confirmed that ICIPE 7 has the potential to infect and cause mortality to the three exposed arthropods, though at slower rate, thus requiring further validation under field conditions.
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Affiliation(s)
- Fedinand Ong’wen
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi P.O. Box 30772-00100, Kenya; (M.M.N.); (U.F.); (T.B.)
- Department of Zoology and Entomology, Faculty of Natural & Agricultural Sciences, University of Pretoria, Private Bag x 20, Hatfield 0028, South Africa;
| | - Margaret Mendi Njoroge
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi P.O. Box 30772-00100, Kenya; (M.M.N.); (U.F.); (T.B.)
| | - Ulrike Fillinger
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi P.O. Box 30772-00100, Kenya; (M.M.N.); (U.F.); (T.B.)
| | - Heike Lutermann
- Department of Zoology and Entomology, Faculty of Natural & Agricultural Sciences, University of Pretoria, Private Bag x 20, Hatfield 0028, South Africa;
| | - Tullu Bukhari
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi P.O. Box 30772-00100, Kenya; (M.M.N.); (U.F.); (T.B.)
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Entomopathogenic Fungi as a Potential Management Tool for the Control of Urban Malaria Vector, Anopheles stephensi (Diptera: Culicidae). J Fungi (Basel) 2023; 9:jof9020223. [PMID: 36836337 PMCID: PMC9966075 DOI: 10.3390/jof9020223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/13/2022] [Accepted: 12/14/2022] [Indexed: 02/11/2023] Open
Abstract
Anopheles stephensi (Diptera: Culicidae) is the vector of urban malaria in India and has a significant impact in transmitting infection in cities and towns. Further, WHO has also alarmed its invasive nature as a threat to African countries. Entomopathogenic fungi such as Beauveria bassiana and Metarhizium anisopliae have been found to be highly effective in controlling vector mosquito populations and therefore could be used in integrated vector control programs. Before employing the entomopathogenic fungi into the control programs, an effective isolate must be selected. Two separate experiments were conducted to evaluate the efficacy of Beauveria bassiana (Bb5a and Bb-NBAIR) and Metarhizium anisopliae (Ma4 and Ma-NBAIR) isolates against An. stephensi. Cement and mud panels were treated with fungal conidia with the concentration of 1 × 107 conidia/mL and adult An. stephensi mosquitoes were exposed to the treated panels (24 h after conidia were applied) by conducting WHO cone bioassay tests. The survival of the mosquitoes was monitored daily until the 10th day. In the second experiment, second instar larvae of An. stephensi were treated with fungal (Bb5a, Bb-NBAIR, Ma4 and Ma-NBAIR) conidia and blastospores with the spore concentration of 1 × 107 spores/mL. The survival of larvae was monitored until pupation. All the fungal isolates tested caused mortality in the adult mosquitoes, with varying median survival times. The Bb5a isolate reported lesser median survival times on both cement and mud panels (6 days). The treated mosquitoes showed similar survival rates for each fungal isolate irrespective of the panel type. There was no mortality in the treated larvae; however, a delay in larval development to pupae was observed compared with the untreated control larvae. Ma4-treated larvae took 11 days (95% CI = 10.7-11.2) to become pupae when compared with the untreated control larvae (6 days [95% CI = 5.6-6.3]). The findings of this study will be useful to consider EPF as a tool for the management of vector mosquitoes.
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Genetics and immunity of Anopheles response to the entomopathogenic fungus Metarhizium anisopliae overlap with immunity to Plasmodium. Sci Rep 2022; 12:6315. [PMID: 35428783 PMCID: PMC9012835 DOI: 10.1038/s41598-022-10190-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 03/28/2022] [Indexed: 11/08/2022] Open
Abstract
Entomopathogenic fungi have been explored as a potential biopesticide to counteract the insecticide resistance issue in mosquitoes. However, little is known about the possibility that genetic resistance to fungal biopesticides could evolve in mosquito populations. Here, we detected an important genetic component underlying Anopheles coluzzii survival after exposure to the entomopathogenic fungus Metarhizium anisopliae. A familiality study detected variation for survival among wild mosquito isofemale pedigrees, and genetic mapping identified two loci that significantly influence mosquito survival after fungus exposure. One locus overlaps with a previously reported locus for Anopheles susceptibility to the human malaria parasite Plasmodium falciparum. Candidate gene studies revealed that two LRR proteins encoded by APL1C and LRIM1 genes in this newly mapped locus are required for protection of female A. coluzzii from M. anisopliae, as is the complement-like factor Tep1. These results indicate that natural Anopheles populations already segregate frequent genetic variation for differential mosquito survival after fungal challenge and suggest a similarity in Anopheles protective responses against fungus and Plasmodium. However, this immune similarity raises the possibility that fungus-resistant mosquitoes could also display enhanced resistance to Plasmodium, suggesting an advantage of selecting for fungus resistance in vector populations to promote naturally diminished malaria vector competence.
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Scott J. Proposed Integrated Control of Zoonotic Plasmodium knowlesi in Southeast Asia Using Themes of One Health. Trop Med Infect Dis 2020; 5:E175. [PMID: 33233871 PMCID: PMC7709578 DOI: 10.3390/tropicalmed5040175] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/15/2020] [Accepted: 11/18/2020] [Indexed: 01/28/2023] Open
Abstract
Zoonotic malaria, Plasmodium knowlesi, threatens the global progression of malaria elimination. Southeast Asian regions are fronting increased zoonotic malaria rates despite the control measures currently implemented-conventional measures to control human-malaria neglect P. knowlesi's residual transmission between the natural macaque host and vector. Initiatives to control P. knowlesi should adopt themes of the One Health approach, which details that the management of an infectious disease agent should be scrutinized at the human-animal-ecosystem interface. This review describes factors that have conceivably permitted the emergence and increased transmission rates of P. knowlesi to humans, from the understanding of genetic exchange events between subpopulations of P. knowlesi to the downstream effects of environmental disruption and simian and vector behavioral adaptations. These factors are considered to advise an integrative control strategy that aligns with the One Health approach. It is proposed that surveillance systems address the geographical distribution and transmission clusters of P. knowlesi and enforce ecological regulations that limit forest conversion and promote ecosystem regeneration. Furthermore, combining individual protective measures, mosquito-based feeding trapping tools and biocontrol strategies in synergy with current control methods may reduce mosquito population density or transmission capacity.
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Affiliation(s)
- Jessica Scott
- College of Public Health and Medical and Veterinary Sciences, Australian Institute of Tropical Health and Medicine, James Cook University, Townsville 4811, Australia
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Ong'wen F, Onyango PO, Bukhari T. Direct and indirect effects of predation and parasitism on the Anopheles gambiae mosquito. Parasit Vectors 2020; 13:43. [PMID: 32000840 PMCID: PMC6990496 DOI: 10.1186/s13071-020-3915-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 01/24/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A good understanding of mosquito ecology is imperative for integrated vector control of malaria. In breeding sites, Anopheles larvae are concurrently exposed to predators and parasites. However, to our knowledge, there is no study on combined effects of predators and parasites on development and survival of larvae and their carry-over effects on adult survivorship and susceptibility to further parasite infection. METHODS This study focused on effects of the nymphs of the dragonfly Pantala flavescens and the parasitic fungus Beauveria bassiana on Anopheles gambiae, to determine: predation efficacy of nymphs against An. gambiae larvae; development rate of An. gambiae larvae in the presence of one, two or four constrained nymphs; efficacy of B. bassiana against An. gambiae larvae at doses of 3, 6 and 12 mg; and survival of adult mosquitoes exposed to B. bassiana, following pre-exposure to a constrained predator and/or parasite at the larval stage. The experiments consisted of survival bioassays quantified as pupation day, or dead larvae and/or adults. RESULTS Nymphs had an average predation efficacy of 88.3% (95% CI: 87.5-89.1) at 24 hours, against An. gambiae larvae. The presence of one or two nymphs reduced development time of larvae by 0.65 and 0.35 days, respectively. However, development time of larvae exposed to four nymphs was similar to the control larvae. Larvae exposed to 3, 6 and 12 mg of B. bassiana were 2.0, 2.5 and 3.5 times more likely to die, respectively, compared to control larvae. Adults not pre-exposed, those pre-exposed to predator, parasite, or both were 45.8, 67.4, 50.9 and 112.0 times more likely to die, respectively, compared to control that were unexposed to predator or parasite, at larval and adult stage. CONCLUSIONS This study shows that both predator and parasite can reduce larval population of An. gambiae, and presence of predator cues decreases development time in breeding sites, as well as, increases the susceptibility of emerging adult to fungus. Predator and parasite both have an additive effect on survival of adults exposed to B. bassiana. Field studies are required for an in-depth understanding of predator and parasite influence on mosquito development time, survival and susceptibility in nature.
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Affiliation(s)
- Fedinand Ong'wen
- Department of Zoology, School of Physical and Biological Sciences, Maseno University, Maseno, Kenya
| | - Patrick Ogola Onyango
- Department of Zoology, School of Physical and Biological Sciences, Maseno University, Maseno, Kenya
| | - Tullu Bukhari
- Department of Zoology, School of Physical and Biological Sciences, Maseno University, Maseno, Kenya.
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Wasinpiyamongkol L, Kanchanaphum P. Isolating and identifying fungi to determine whether their biological properties have the potential to control the population density of mosquitoes. Heliyon 2019; 5:e02331. [PMID: 31508522 PMCID: PMC6726841 DOI: 10.1016/j.heliyon.2019.e02331] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/24/2019] [Accepted: 08/15/2019] [Indexed: 01/24/2023] Open
Abstract
Mosquitoes transmit diseases such as dengue, chikungunya, Zika, and yellow fever to humans. Biological control methods are required for these insects because they can be environmentally friendlier, safer, and more cost-effective than chemical or physical methods currently available. The aim of this research is to identify fungi found in mosquito breeding containers that have the potential to control the population density of mosquitoes. For the identification, water samples were taken from mosquito breeding containers situated in seven districts of Bangkok to obtain pure cultures. Deoxyribonucleic acid (DNA) was extracted from the cultures then sent for sequencing and analyzing. The results show that fourteen strains of fungi were isolated. The most common strain found was Aspergillus spp., which was present in 31 of the 78 fungi samples. The strains Metarhizium anisopliae and Penicilium citrinum were found to be interesting because they may have the potential to act as entomopathogenic fungi. The biological properties of these strains should be further investigated because they could help in the fight against mosquito-borne diseases.
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Affiliation(s)
| | - Panan Kanchanaphum
- Biochemistry Unit, Faculty of Science, Rangsit University, Pathumthani, Thailand
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Tawidian P, Rhodes VL, Michel K. Mosquito-fungus interactions and antifungal immunity. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 111:103182. [PMID: 31265904 PMCID: PMC6639037 DOI: 10.1016/j.ibmb.2019.103182] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 06/28/2019] [Indexed: 05/14/2023]
Abstract
The mosquito immune system has evolved in the presence of continuous encounters with fungi that range from food to foes. Herein, we review the field of mosquito-fungal interactions, providing an overview of current knowledge and topics of interest. Mosquitoes encounter fungi in their aquatic and terrestrial habitats. Mosquito larvae are exposed to fungi on plant detritus, within the water column, and at the water surface. Adult mosquitoes are exposed to fungi during indoor and outdoor resting, blood and sugar feeding, mating, and oviposition. Fungi enter the mosquito body through different routes, including ingestion and through active or passive breaches in the cuticle. Oral uptake of fungi can be beneficial to mosquitoes, as yeasts hold nutritional value and support larval development. However, ingestion of or surface contact with fungal entomopathogens leads to colonization of the mosquito with often lethal consequences to the host. The mosquito immune system recognizes fungi and mounts cellular and humoral immune responses in the hemocoel, and possibly epithelial immune responses in the gut. These responses are regulated transcriptionally through multiple signal transduction pathways. Proteolytic protease cascades provide additional regulation of antifungal immunity. Together, these immune responses provide an efficient barrier to fungal infections, which need to be overcome by entomopathogens. Therefore, fungi constitute an excellent tool to examine the molecular underpinnings of mosquito immunity and to identify novel antifungal peptides. In addition, recent advances in mycobiome analyses can now be used to examine the contribution of fungi to various mosquito traits, including vector competence.
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Affiliation(s)
- P Tawidian
- Division of Biology, Kansas State University, 267 Chalmers Hall, Manhattan, KS, 66506, USA
| | - V L Rhodes
- Missouri Southern State University, Biology Department, Reynolds Hall 220, 3950 E. Newman Rd., Joplin, MO, 64801-1595, USA
| | - K Michel
- Division of Biology, Kansas State University, 267 Chalmers Hall, Manhattan, KS, 66506, USA.
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Weeks EN, Machtinger ET, Leemon D, Geden CJ. 12. Biological control of livestock pests: entomopathogens. ECOLOGY AND CONTROL OF VECTOR-BORNE DISEASES 2018. [DOI: 10.3920/978-90-8686-863-6_12] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Emma N.I. Weeks
- University of Florida, Entomology and Nematology Dept., 970 Natural Area Drive, Gainesville, FL 32653, USA
| | - Erika T. Machtinger
- Penn State University, Department of Entomology, 501 ASI Building, University Park, State College, PA 16082, USA
| | - Diana Leemon
- Department of Agriculture and Fisheries (Queensland), Agri-Science Queensland, Ecosciences Precinct, GPO Box 267, Brisbane, Queensland, 4001, Australia
| | - Christopher J. Geden
- United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology, 1600 SW 23rd Drive, Gainesville, FL 32608, USA
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Rhodes VL, Thomas MB, Michel K. The interplay between dose and immune system activation determines fungal infection outcome in the African malaria mosquito, Anopheles gambiae. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 85:125-133. [PMID: 29649553 PMCID: PMC5935592 DOI: 10.1016/j.dci.2018.04.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 04/05/2018] [Accepted: 04/06/2018] [Indexed: 05/27/2023]
Abstract
The Toll pathway is a central regulator of antifungal immunity in insects. In mosquitoes, the Toll pathway affects infections with the fungal entomopathogen, Beauveria bassiana, which is considered a potential mosquito biopesticide. We report here the use of B. bassiana strain I93-825 in Anopheles gambiae to analyze the impact of Toll pathway modulation on mosquito survival. Exposure to a narrow dose range of conidia by direct contact decreased mosquito longevity and median survival. In addition, fungal exposure dose correlated positively and linearly with hazard ratio. Increased Toll signaling by knockdown of its inhibitor, cactus, decreased survivorship of uninfected females, increased mosquito survival after low dose B. bassiana exposure, but had little effect following exposure to higher doses. This observed trade-off could have implications for development of B. bassiana as a prospective vector control tool. On the one hand, selection for small increases in mosquito immune signaling across a narrow dose range could impair efficacy of B. bassiana. On the other hand, costs of immunity and the capacity for higher doses of fungus to overwhelm immune responses could limit evolution of resistance.
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Affiliation(s)
- Victoria L Rhodes
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Matthew B Thomas
- Department of Entomology and Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Kristin Michel
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
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Benelli G, Jeffries CL, Walker T. Biological Control of Mosquito Vectors: Past, Present, and Future. INSECTS 2016; 7:insects7040052. [PMID: 27706105 PMCID: PMC5198200 DOI: 10.3390/insects7040052] [Citation(s) in RCA: 183] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 09/28/2016] [Indexed: 11/16/2022]
Abstract
Mosquitoes represent the major arthropod vectors of human disease worldwide transmitting malaria, lymphatic filariasis, and arboviruses such as dengue virus and Zika virus. Unfortunately, no treatment (in the form of vaccines or drugs) is available for most of these diseases and vector control is still the main form of prevention. The limitations of traditional insecticide-based strategies, particularly the development of insecticide resistance, have resulted in significant efforts to develop alternative eco-friendly methods. Biocontrol strategies aim to be sustainable and target a range of different mosquito species to reduce the current reliance on insecticide-based mosquito control. In this review, we outline non-insecticide based strategies that have been implemented or are currently being tested. We also highlight the use of mosquito behavioural knowledge that can be exploited for control strategies.
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Affiliation(s)
- Giovanni Benelli
- Insect Behaviour Group, Department of Agriculture, Food and Environment, University of Pisa, Pisa 56124, Italy.
| | - Claire L Jeffries
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
| | - Thomas Walker
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
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Spitzen J, Koelewijn T, Mukabana WR, Takken W. Visualization of house-entry behaviour of malaria mosquitoes. Malar J 2016; 15:233. [PMID: 27108961 PMCID: PMC4843208 DOI: 10.1186/s12936-016-1293-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 04/14/2016] [Indexed: 12/02/2022] Open
Abstract
Background Malaria mosquitoes often blood feed indoors on human hosts. The mosquitoes predominantly enter houses via open eaves. Host-seeking is odour-driven, and finding a host depends on the quality of the odour plume and whether the route towards the host is free of obstructions. Little is known about in-flight behaviour of mosquitoes during house entry. This semi-field study visualizes mosquito house entry in three dimensions (3D) and offers new insights for optimizing vector control interventions. Methods The approach and house entry of Anopheles gambiae sensu stricto was studied in a semi-field set-up using video-recorded flight tracks and 3D analysis. Behavioural parameters of host-seeking female mosquitoes were visualized with respect to their position relative to the eave as well as whether a mosquito would enter or not. Host odour was standardized using an attractive synthetic blend in addition to CO2. The study was conducted in western Kenya at the Thomas Odhiambo Campus of the International Centre of Insect Physiology and Ecology, Mbita. Results The majority of host-seeking An. gambiae approached a house with a flight altitude at eave level, arriving within a horizontal arc of 180°. Fifty-five per cent of mosquitoes approaching a house did not enter or made multiple attempts before passing through the eave. During approach, mosquitoes greatly reduced their speed and the flight paths became more convoluted. As a result, mosquitoes that passed through the eave spent more than 80 % of the observed time within 30 cm of the eave. Mosquitoes that exited the eave departed at eave level and followed the edge of the roof (12.5 %) or quickly re-entered after exiting (9.6 %). Conclusions The study shows that host-seeking mosquitoes, when entering a house, approach the eave in a wide angle to the house at eave level. Less than 25 % of approaching mosquitoes entered the house without interruption, whereas 12.5 % of mosquitoes that had entered left the house again within the time of observation. Advances in tracking techniques open a new array of questions that can now be answered to improve household interventions that combat malaria transmission. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1293-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jeroen Spitzen
- Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands.
| | - Teun Koelewijn
- Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands
| | - W Richard Mukabana
- International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya.,School of Biological Sciences, University of Nairobi, P.O. Box 30197 GPO, Nairobi, Kenya
| | - Willem Takken
- Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands
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Heinig RL, Thomas MB. Interactions between a fungal entomopathogen and malaria parasites within a mosquito vector. Malar J 2015; 14:22. [PMID: 25626485 PMCID: PMC4318179 DOI: 10.1186/s12936-014-0526-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 12/21/2014] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Mosquitoes are becoming increasingly resistant to the chemical insecticides currently available for malaria vector control, spurring interest in alternative management tools. One promising technology is the use of fungal entomopathogens. Fungi have been shown to impact the potential for mosquitoes to transmit malaria by reducing mosquito longevity and altering behaviour associated with flight and host location. Additionally, fungi could impact the development of malaria parasites within the mosquito via competition for resources or effects on the mosquito immune system. This study evaluated whether co-infection or superinfection with the fungal entomopathogen Beauveria bassiana affected malaria infection progress in Anopheles stephensi mosquitoes. METHODS The study used two parasite species to examine possible effects of fungal infection at different parasite development stages. First, the rodent malaria model Plasmodium yoelii was used to explore interactions at the oocyst stage. Plasmodium yoelii produces high oocyst densities in infected mosquitoes and thus was expected to maximize host immunological and resource demands. Second, fungal interactions with mature sporozoites were evaluated by infecting mosquitoes with the human malaria species Plasmodium falciparum, which is highly efficient at invading mosquito salivary glands. RESULTS With P. yoelii, there was no evidence that fungal co-infection (on the same day as the blood meal) or superinfection (during a subsequent gonotrophic cycle after parasite infection) affected the proportion of mosquitoes with oocysts, the number of oocysts per infected mosquito or the number of sporozoites per oocyst. Similarly, for P. falciparum, there was no evidence that fungal infection affected sporozoite prevalence. Furthermore, there was no impact of infection with either malaria species on fungal virulence as measured by mosquito survival time. CONCLUSIONS These results suggest that the impact of fungus on malaria control potential is limited to the well-established effects on mosquito survival and transmission behaviour. Direct or indirect interactions between fungus and malaria parasites within mosquitoes appear to have little additional influence.
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Affiliation(s)
- Rebecca L Heinig
- Merkle Laboratory, The Pennsylvania State University, University Park, PA, 16803, USA.
| | - Matthew B Thomas
- Merkle Laboratory, The Pennsylvania State University, University Park, PA, 16803, USA.
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Natural variation in virulence of the entomopathogenic fungus Beauveria bassiana against malaria mosquitoes. Malar J 2014; 13:479. [PMID: 25480526 PMCID: PMC4364330 DOI: 10.1186/1475-2875-13-479] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 11/30/2014] [Indexed: 11/29/2022] Open
Abstract
Background Insecticide resistance is greatly hampering current efforts to control malaria and therefore alternative methods are needed. Entomopathogenic fungi have been proposed as an alternative with a special focus on the cosmopolitan species Beauveria bassiana. However, few studies have analysed the effects of natural variation within fungal isolates on mosquito survival, and the implications and possible exploitation for malaria control. Methods Laboratory bioassays were performed on adult female mosquitoes (Anopheles coluzzii) with spores from 29 isolates of B. bassiana, originating from different parts of the world. In addition, phenotypic characteristics of the fungal isolates such as sporulation, spore size and growth rate were studied to explore their relationship with virulence. Results All tested isolates of B. bassiana killed An. coluzzii mosquitoes, and the rate at which this happened differed significantly among the isolates. The risk of mosquitoes dying was around ten times higher when they were exposed to the most virulent as compared to the least virulent isolate. There was significant variation among isolates in spore size, growth rate and sporulation, but none of these morphological characteristics were correlated, and thus predictive, for the ability of the fungal isolate to kill malaria mosquitoes. Conclusions This study shows that there is a wide natural variation in virulence of isolates of B. bassiana, and that selecting an appropriate fungal isolate is highly relevant in killing and thus controlling malaria mosquitoes, particularly if used as part of an integrated vector management strategy. Also, the wide variation observed in virulence offers the opportunity to better understand the molecular and genetic mechanisms that drive this variation and thus to address the potential development of resistance against entomopathogenic fungi.
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Laboratory evolution of the entomopathogenic fungus Beauveria bassiana against Anopheles stephensi larvae (Diptera: Culicidae). ASIAN PACIFIC JOURNAL OF TROPICAL DISEASE 2014. [DOI: 10.1016/s2222-1808(14)60730-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Carolino AT, Paula AR, Silva CP, Butt TM, Samuels RI. Monitoring persistence of the entomopathogenic fungus Metarhizium anisopliae under simulated field conditions with the aim of controlling adult Aedes aegypti (Diptera: Culicidae). Parasit Vectors 2014; 7:198. [PMID: 24766705 PMCID: PMC4021620 DOI: 10.1186/1756-3305-7-198] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 04/09/2014] [Indexed: 11/30/2022] Open
Abstract
Background Entomopathogenic fungi are potential candidates for use in integrated vector management, with recent emphasis aimed at developing adult mosquito control methods. Here we investigated the persistence of the fungus Metarhizium anisopliae when tested against female A. aegypti under field conditions. Methods Black cotton cloths impregnated with M. anisopliae conidia, formulated in vegetable oil + isoparaffin, were maintained on a covered veranda for up to 30 days. At specific times, pieces of the cloths were removed, placed in Tween 80 and the resuspended conidia were sprayed directly onto mosquitoes. The persistence of conidia impregnated on black cloths using three different carriers was evaluated in test rooms. Fifty mosquitoes were released into each room and after a 5 day period, the surviving insects were captured. Another 50 insects were then released into each room. The capacity of the fungus at reducing mosquito survival was evaluated over a total of 35 days. Results Conidia extracted from cloths maintained on the veranda for 2 to 18 days remained virulent, with 28 to 60% mosquito survival observed. Mosquito survival following exposure to fungus impregnated cloths showed that fungus + Tween caused similar reductions to that of fungus + vegetable oil. Mosquitoes exposed to the formulation fungus + vegetable oil had survival rates of 36% over the first 5 days of the experiment. Following the release of the second cohort of mosquitoes (6-11days), survival increased to 50%. The survival of the 12–17 day cohort (78%) was statistically equal to that of the controls (84%). Formulation of the fungus in vegetable oil + isoparaffin increased the persistence of the fungus, with the 18–23 day cohort (64% survival) still showing statistical differences to that of the controls (87% survival). Conclusions The potential of entomopathogenic fungi for the control of adult A. aegypti was confirmed under field conditions. Vegetable oil + isoparaffin formulations of M. anisopliae significantly increased the effectiveness of the fungus, thus reducing the need for frequent changes of black cloths in residences. Our future aim is to obtain effective control of mosquito populations, with cloths only needing to being replaced once a month.
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Affiliation(s)
| | | | | | | | - Richard I Samuels
- Department of Entomology and Plant Pathology, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Rio de Janeiro 28013-602, Brazil.
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Vogels CBF, Bukhari T, Koenraadt CJM. Fitness consequences of larval exposure to Beauveria bassiana on adults of the malaria vector Anopheles stephensi. J Invertebr Pathol 2014; 119:19-24. [PMID: 24694552 DOI: 10.1016/j.jip.2014.03.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 02/23/2014] [Accepted: 03/18/2014] [Indexed: 11/25/2022]
Abstract
Entomopathogenic fungi have shown to be effective in biological control of both larval and adult stages of malaria mosquitoes. However, a small fraction of mosquitoes is still able to emerge after treatment with fungus during the larval stage. It remains unclear whether fitness of these adults is affected by the treatment during the larval stage and whether they are still susceptible for another treatment during the adult stage. Therefore, we tested the effects of larval exposure to the entomopathogenic fungus Beauveria bassiana on fitness of surviving Anopheles stephensi females. Furthermore, we tested whether larval exposed females were still susceptible to re-exposure to the fungus during the adult stage. Sex ratio, survival and reproductive success were compared between non-exposed and larval exposed A. stephensi. Comparisons were also made between survival of non-exposed and larval exposed females that were re-exposed to B. bassiana during the adult stage. Larval treatment did not affect sex ratio of emerging mosquitoes. Larval exposed females that were infected died significantly faster and laid equal numbers of eggs from which equal numbers of larvae hatched, compared to non-exposed females. Larval exposed females that were uninfected had equal survival, but laid a significantly larger number of eggs from which a significantly higher number of larvae hatched, compared to non-exposed females. Larval exposed females which were re-exposed to B. bassiana during the adult stage had equal survival as females exposed only during the adult stage. Our results suggest that individual consequences for fitness of larval exposed females depended on whether a fungal infection was acquired during the larval stage. Larval exposed females remained susceptible to re-exposure with B. bassiana during the adult stage, indicating that larval and adult control of malaria mosquitoes with EF are compatible.
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Affiliation(s)
- Chantal B F Vogels
- Laboratory of Entomology, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
| | - Tullu Bukhari
- Laboratory of Entomology, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; Unit of Insect Vector Genetics and Genomics, Institute Pasteur, 25-28, Rue du Docteur Roux, 75724 Paris, France.
| | - Constantianus J M Koenraadt
- Laboratory of Entomology, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
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Killeen GF, Chitnis N. Potential causes and consequences of behavioural resilience and resistance in malaria vector populations: a mathematical modelling analysis. Malar J 2014; 13:97. [PMID: 24629066 PMCID: PMC3995604 DOI: 10.1186/1475-2875-13-97] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 03/06/2014] [Indexed: 11/10/2022] Open
Abstract
Background The ability of mosquitoes to evade fatal exposure to insecticidal nets and sprays represents the primary obstacle to eliminating malaria. However, it remains unclear which behaviours are most important for buffering mosquito and parasite populations against vector control. Methods Simulated life histories were used to compare the impact of alternative feeding behaviour strategies upon overall lifetime feeding success, and upon temporal distributions of successful feeds and biting rates experienced by unprotected humans, in the presence and absence of insecticidal nets. Strictly nocturnal preferred feeding times were contrasted with 1) a wider preference window extending to dawn and dusk, and 2) crepuscular preferences wherein foraging is suppressed when humans sleep and can use nets but is maximal immediately before and after. Simulations with diversion and mortality parameters typical of endophagic, endophilic African vectors, such as Anopheles gambiae and Anopheles funestus, were compared with those for endophagic but exophilic species, such as Anopheles arabiensis, that also enter houses but leave earlier before lethal exposure to insecticide-treated surfaces occurs. Results Insecticidal nets were predicted to redistribute successful feeding events to dawn and dusk where these were included in the profile of innately preferred feeding times. However, predicted distributions of biting unprotected humans were unaffected because extended host-seeking activity was redistributed to innately preferred feeding times. Recently observed alterations of biting activity distributions therefore reflect processes not captured in this model, such as evolutionary selection of heritably modified feeding time preferences or phenotypically plastic expression of feeding time preference caused by associative learning. Surprisingly, endophagy combined with exophily, among mosquitoes that enter houses but then feed and/or rest briefly before rapidly exiting, consistently attenuated predicted insecticide impact more than any feeding time preference trait. Conclusions Regardless of underlying cause, recent redistributions of host-biting activity to dawn and dusk necessitate new outdoor control strategies. However, persistently indoor-feeding vectors, that evade intradomiciliary insecticide exposure, are at least equally important. Fortunately, recent evaluations of occupied houses or odour-baited stations, with baffled entrances that retain An. arabiensis within insecticide-treated structures, illustrate how endophagic but exophilic vectors may be more effectively tackled using existing insecticides.
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Affiliation(s)
- Gerry F Killeen
- Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, PO Box 53, Ifakara, Kilombero, Morogoro, United Republic of Tanzania.
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Testing fungus impregnated cloths for the control of adult Aedes aegypti under natural conditions. Parasit Vectors 2013; 6:256. [PMID: 24010874 PMCID: PMC3848359 DOI: 10.1186/1756-3305-6-256] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 09/01/2013] [Indexed: 11/25/2022] Open
Abstract
Background Entomopathogenic fungi could be useful tools for reducing populations of the dengue mosquito Aedes aegypti. Here the efficiency of fungus (Metarhizium anisopliae) impregnated cloths (with and without imidacloprid [IMI]) was evaluated against adult A. aegypti in simulated human dwellings. Behaviour of mosquitoes in the presence of black cloths was also investigated. Findings When mosquitoes were released into the test rooms, the lowest survival rates (38%) were seen when five black cloths impregnated with conidia of ESALQ 818 + 10 ppm IMI were fixed under tables and chairs. This result was significantly lower than the survival rate recorded when cloths were impregnated with ESALQ 818 alone (44%) or ESALQ 818 + 0.1 ppm IMI (43%). Blood fed A. aegypti had lower landing frequencies on black cloths than sucrose fed insects during the first 24 h following feeding, which may have been due to reduced flight activity. Few mosquitoes (4-5%) were observed to land on the cloths during the hours of darkness. The landing pattern of sucrose-fed mosquitoes on non-treated and fungus-treated cloths was similar. Conclusion The synergism between M. anisopliae and IMI significantly reduced Aedes survival in simulated field conditions. The use of fungus impregnated cloths is a promising point source application method for the control of adult A. aegypti.
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Blanford S, Jenkins NE, Read AF, Thomas MB. Evaluating the lethal and pre-lethal effects of a range of fungi against adult Anopheles stephensi mosquitoes. Malar J 2012; 11:365. [PMID: 23126549 PMCID: PMC3520692 DOI: 10.1186/1475-2875-11-365] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 10/05/2012] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Insecticide resistance is seriously undermining efforts to eliminate malaria. In response, research on alternatives to the use of chemical insecticides against adult mosquito vectors has been increasing. Fungal entomopathogens formulated as biopesticides have received much attention and have shown considerable potential. This research has necessarily focused on relatively few fungal isolates in order to 'prove concept'. Further, most attention has been paid to examining fungal virulence (lethality) and not the other properties of fungal infection that might also contribute to reducing transmission potential. Here, a range of fungal isolates were screened to examine variation in virulence and how this relates to additional pre-lethal reductions in feeding propensity. METHODS The Asian malaria vector, Anopheles stephensi was exposed to 17 different isolates of entomopathogenic fungi belonging to species of Beauveria bassiana, Metarhizium anisopliae, Metarhizium acridum and Isaria farinosus. Each isolate was applied to a test substrate at a standard dose rate of 1×109 spores ml-1 and the mosquitoes exposed for six hours. Subsequently the insects were removed to mesh cages where survival was monitored over the next 14 days. During this incubation period the mosquitoes' propensity to feed was assayed for each isolate by offering a feeding stimulant at the side of the cage and recording the number probing. RESULTS AND CONCLUSIONS Fungal isolates showed a range of virulence to A. stephensi with some causing >80% mortality within 7 days, while others caused little increase in mortality relative to controls over the study period. Similarly, some isolates had a large impact on feeding propensity, causing >50% pre-lethal reductions in feeding rate, whereas other isolates had very little impact. There was clear correlation between fungal virulence and feeding reduction with virulence explaining nearly 70% of the variation in feeding reduction. However, there were some isolates where either feeding decline was not associated with high virulence, or virulence did not automatically prompt large declines in feeding. These results are discussed in the context of choosing optimum fungal isolates for biopesticide development.
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Affiliation(s)
- Simon Blanford
- Center for Infectious Disease Dynamics, Department of Biology, Penn State University Mueller Laboratory, University Park, PA 16802, USA.
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Does Cattle Milieu Provide a Potential Point to Target Wild Exophilic Anopheles arabiensis (Diptera: Culicidae) with Entomopathogenic Fungus? A Bioinsecticide Zooprophylaxis Strategy for Vector Control. J Parasitol Res 2012; 2012:280583. [PMID: 22934152 PMCID: PMC3425831 DOI: 10.1155/2012/280583] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 06/30/2012] [Indexed: 11/17/2022] Open
Abstract
Background. Anopheles arabiensis is increasingly dominating malaria transmission in Africa. The exophagy in mosquitoes threatens the effectiveness of indoor vector control strategies. This study aimed to evaluate the effectiveness of fungus against An. arabiensis when applied on cattle and their environments. Methods. Experiments were conducted under semi-field and small-scale field conditions within Kilombero valley. The semi-field reared females of 5–7 days old An. arabiensis were exposed to fungus-treated and untreated calf. Further, wild An. arabiensis were exposed to fungus-treated calves, mud-huts, and their controls. Mosquitoes were recaptured the next morning and proportion fed, infected, and survived were evaluated. Experiments were replicated three times using different individuals of calves. Results. A high proportion of An. arabiensis was fed on calves (>0.90) and become infected (0.94) while resting on fungus-treated mud walls than on other surfaces. However, fungus treatments reduced fecundity and survival of mosquitoes.
Conclusion. This study demonstrates for the first time the potential of cattle and their milieu for controlling An. arabiensis. Most of An. arabiensis were fed and infected while resting on fungus-treated mud walls than on other surfaces. Fungus treatments reduced fecundity and survival of mosquitoes. These results suggest deployment of bioinsecticide zooprophylaxis against exophilic An. arabiensis.
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Singh G, Prakash S. Lethal effects of Aspergillus niger against mosquitoes vector of filaria, malaria, and dengue: a liquid mycoadulticide. ScientificWorldJournal 2012; 2012:603984. [PMID: 22629156 PMCID: PMC3354556 DOI: 10.1100/2012/603984] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 01/09/2012] [Indexed: 11/18/2022] Open
Abstract
Aspergillus niger is a fungus of the genus Aspergillus. It has caused a disease called black mold on certain fruits and vegetables. The culture filtrates released from the A. niger ATCC 66566 were grown in Czapek dox broth (CDB) then filtered with flash chromatograph and were used for the bioassay after a growth of thirty days. The result demonstrated these mortalities with LC50, LC90, and LC99 values of Culex quinquefasciatus 0.76, 3.06, and 4.75, Anopheles stephensi 1.43, 3.2, and 3.86, and Aedes aegypti 1.43, 2.2, and 4.1 μl/cm2, after exposure of seven hours. We have calculated significant LT90 values of Cx. quinquefasciatus 4.5, An. stephensi 3.54, and Ae. aegypti 6.0 hrs, respectively. This liquid spray of fungal culture isolate of A. niger can reduce malaria, dengue, and filarial transmission. These results significantly support broadening the current vector control paradigm beyond chemical adulticides.
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Affiliation(s)
- Gavendra Singh
- Environmental and Advanced Parasitology and Vector Control Biotechnology Laboratories, Department of Zoology, Faculty of Science, Dayalbagh Educational Institute, Dayalbagh, Agra 282005, India
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Mnyone LL, Lyimo IN, Lwetoijera DW, Mpingwa MW, Nchimbi N, Hancock PA, Russell TL, Kirby MJ, Takken W, Koenraadt CJM. Exploiting the behaviour of wild malaria vectors to achieve high infection with fungal biocontrol agents. Malar J 2012; 11:87. [PMID: 22449130 PMCID: PMC3337815 DOI: 10.1186/1475-2875-11-87] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 03/26/2012] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Control of mosquitoes that transmit malaria has been the mainstay in the fight against the disease, but alternative methods are required in view of emerging insecticide resistance. Entomopathogenic fungi are candidate alternatives, but to date, few trials have translated the use of these agents to field-based evaluations of their actual impact on mosquito survival and malaria risk. Mineral oil-formulations of the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were applied using five different techniques that each exploited the behaviour of malaria mosquitoes when entering, host-seeking or resting in experimental huts in a malaria endemic area of rural Tanzania. RESULTS Survival of mosquitoes was reduced by 39-57% relative to controls after forcing upward house-entry of mosquitoes through fungus treated baffles attached to the eaves or after application of fungus-treated surfaces around an occupied bed net (bed net strip design). Moreover, 68 to 76% of the treatment mosquitoes showed fungal growth and thus had sufficient contact with fungus treated surfaces. A population dynamic model of malaria-mosquito interactions shows that these infection rates reduce malaria transmission by 75-80% due to the effect of fungal infection on adult mortality alone. The model also demonstrated that even if a high proportion of the mosquitoes exhibits outdoor biting behaviour, malaria transmission was still significantly reduced. CONCLUSIONS Entomopathogenic fungi strongly affect mosquito survival and have a high predicted impact on malaria transmission. These entomopathogens represent a viable alternative for malaria control, especially if they are used as part of an integrated vector management strategy.
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Affiliation(s)
- Ladslaus L Mnyone
- Biomedical and Environmental Group, Ifakara Health Institute, P.O. Box 53, Off Mlabani Passage, Ifakara, Tanzania
- Laboratory of Entomology, Wageningen University and Research Centre, P.O. Box 8031, 6700 EH Wageningen, The Netherlands
- Pest Management Centre, Sokoine University of Agriculture, P.O. Box 3110, Morogoro, Tanzania
| | - Issa N Lyimo
- Biomedical and Environmental Group, Ifakara Health Institute, P.O. Box 53, Off Mlabani Passage, Ifakara, Tanzania
- Faculty of Biomedical and Life Sciences, University of Glasgow, 120 University Place, G12 8TA Glasgow, UK
| | - Dickson W Lwetoijera
- Biomedical and Environmental Group, Ifakara Health Institute, P.O. Box 53, Off Mlabani Passage, Ifakara, Tanzania
| | - Monica W Mpingwa
- Biomedical and Environmental Group, Ifakara Health Institute, P.O. Box 53, Off Mlabani Passage, Ifakara, Tanzania
| | - Nuru Nchimbi
- Biomedical and Environmental Group, Ifakara Health Institute, P.O. Box 53, Off Mlabani Passage, Ifakara, Tanzania
| | | | - Tanya L Russell
- Biomedical and Environmental Group, Ifakara Health Institute, P.O. Box 53, Off Mlabani Passage, Ifakara, Tanzania
- The University of Queensland, School of Population Health, Australian Centre for Tropical and International Health, Brisbane 4006, Australia
- Vector Group, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Matthew J Kirby
- Biomedical and Environmental Group, Ifakara Health Institute, P.O. Box 53, Off Mlabani Passage, Ifakara, Tanzania
- Laboratory of Entomology, Wageningen University and Research Centre, P.O. Box 8031, 6700 EH Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research Centre, P.O. Box 8031, 6700 EH Wageningen, The Netherlands
| | - Constantianus JM Koenraadt
- Laboratory of Entomology, Wageningen University and Research Centre, P.O. Box 8031, 6700 EH Wageningen, The Netherlands
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Soni N, Prakash S. Larvicidal effect of Verticillium lecanii metabolites on Culex quinquefasciatus and Aedes aegypti larvae. ASIAN PACIFIC JOURNAL OF TROPICAL DISEASE 2012. [DOI: 10.1016/s2222-1808(12)60050-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abdul-Ghani R, Al-Mekhlafi AM, Alabsi MS. Microbial control of malaria: biological warfare against the parasite and its vector. Acta Trop 2012; 121:71-84. [PMID: 22100545 DOI: 10.1016/j.actatropica.2011.11.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 10/31/2011] [Accepted: 11/04/2011] [Indexed: 01/31/2023]
Abstract
Microbial applications in malaria transmission control have drawn global attention. Mosquito midgut microbiota can modulate vector immunity and block Plasmodium development. Paratransgenic manipulation of bacterial symbionts and Wolbachia can affect reproductive characteristics of mosquitoes. Bacillus-based biolarvicides can control mosquito larvae in different breeding habitats, but their effectiveness differs according to the type of formulation applied, and the physical and ecological conditions of the environment. Entomopathogenic fungi show promise as effective and evolution-proof agents against adult mosquitoes. In addition, transgenic fungi can express anti-plasmodial effector molecules that can target the parasite inside its vector. Despite showing effectiveness in domestic environments as well as against insecticide-resistant mosquitoes, claims towards their deployability in the field and their possible use in integrated vector management programmes have yet to be investigated. Viral pathogens show efficacy in the interruption of sporogonic development of the parasite, and protozoal pathogens exert direct pathogenic potential on larvae and adults with substantial effects on mosquito longevity and fecundity. However, the technology required for their isolation and maintenance impedes their field application. Many agents show promising findings; however, the question remains about the epidemiologic reality of these approaches because even those that have been tried under field conditions still have certain limitations. This review addresses aspects of the microbial control of malaria between proof-of-concept and epidemiologic reality.
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Fan Y, Borovsky D, Hawkings C, Ortiz-Urquiza A, Keyhani NO. Exploiting host molecules to augment mycoinsecticide virulence. Nat Biotechnol 2012; 30:35-7. [PMID: 22231090 DOI: 10.1038/nbt.2080] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Howard AFV, N'Guessan R, Koenraadt CJM, Asidi A, Farenhorst M, Akogbéto M, Knols BGJ, Takken W. First report of the infection of insecticide-resistant malaria vector mosquitoes with an entomopathogenic fungus under field conditions. Malar J 2011; 10:24. [PMID: 21288359 PMCID: PMC3045381 DOI: 10.1186/1475-2875-10-24] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 02/02/2011] [Indexed: 11/25/2022] Open
Abstract
Background Insecticide-resistant mosquitoes are compromising the ability of current mosquito control tools to control malaria vectors. A proposed new approach for mosquito control is to use entomopathogenic fungi. These fungi have been shown to be lethal to both insecticide-susceptible and insecticide-resistant mosquitoes under laboratory conditions. The goal of this study was to see whether entomopathogenic fungi could be used to infect insecticide-resistant malaria vectors under field conditions, and to see whether the virulence and viability of the fungal conidia decreased after exposure to ambient African field conditions. Methods This study used the fungus Beauveria bassiana to infect the insecticide-resistant malaria vector Anopheles gambiae s.s (Diptera: Culicidae) VKPER laboratory colony strain. Fungal conidia were applied to polyester netting and kept under West African field conditions for varying periods of time. The virulence of the fungal-treated netting was tested 1, 3 and 5 days after net application by exposing An. gambiae s.s. VKPER mosquitoes in WHO cone bioassays carried out under field conditions. In addition, the viability of B. bassiana conidia was measured after up to 20 days exposure to field conditions. Results The results show that B. bassiana infection caused significantly increased mortality with the daily risk of dying being increased by 2.5× for the fungus-exposed mosquitoes compared to the control mosquitoes. However, the virulence of the B. bassiana conidia decreased with increasing time spent exposed to the field conditions, the older the treatment on the net, the lower the fungus-induced mortality rate. This is likely to be due to the climate because laboratory trials found no such decline within the same trial time period. Conidial viability also decreased with increasing exposure to the net and natural abiotic environmental conditions. After 20 days field exposure the conidial viability was 30%, but the viability of control conidia not exposed to the net or field conditions was 79%. Conclusions This work shows promise for the use of B. bassiana fungal conidia against insecticide-resistant mosquitoes in the field, but further work is required to examine the role of environmental conditions on fungal virulence and viability with a view to eventually making the fungal conidia delivery system more able to withstand the ambient African climate.
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Affiliation(s)
- Annabel F V Howard
- Laboratory of Entomology, Wageningen University and Research Centre, P.O. Box 8031, 6700 EH Wageningen, The Netherlands.
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Howard AF, N'guessan R, Koenraadt CJ, Asidi A, Farenhorst M, Akogbéto M, Thomas MB, Knols BG, Takken W. The entomopathogenic fungus Beauveria bassiana reduces instantaneous blood feeding in wild multi-insecticide-resistant Culex quinquefasciatus mosquitoes in Benin, West Africa. Parasit Vectors 2010; 3:87. [PMID: 20843321 PMCID: PMC2946288 DOI: 10.1186/1756-3305-3-87] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 09/15/2010] [Indexed: 02/01/2023] Open
Abstract
Background Mosquito-borne diseases are still a major health risk in many developing countries, and the emergence of multi-insecticide-resistant mosquitoes is threatening the future of vector control. Therefore, new tools that can manage resistant mosquitoes are required. Laboratory studies show that entomopathogenic fungi can kill insecticide-resistant malaria vectors but this needs to be verified in the field. Methods The present study investigated whether these fungi will be effective at infecting, killing and/or modifying the behaviour of wild multi-insecticide-resistant West African mosquitoes. The entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were separately applied to white polyester window netting and used in combination with either a permethrin-treated or untreated bednet in an experimental hut trial. Untreated nets were used because we wanted to test the effect of fungus alone and in combination with an insecticide to examine any potential additive or synergistic effects. Results In total, 1125 female mosquitoes were collected during the hut trial, mainly Culex quinquefasciatus Say. Unfortunately, not enough wild Anopheles gambiae Giles were collected to allow the effect the fungi may have on this malaria vector to be analysed. None of the treatment combinations caused significantly increased mortality of Cx. quinquefasciatus when compared to the control hut. The only significant behaviour modification found was a reduction in blood feeding by Cx. quinquefasciatus, caused by the permethrin and B. bassiana treatments, although no additive effect was seen in the B. bassiana and permethrin combination treatment. Beauveria bassiana did not repel blood foraging mosquitoes either in the laboratory or field. Conclusions This is the first time that an entomopathogenic fungus has been shown to reduce blood feeding of wild mosquitoes. This behaviour modification indicates that B. bassiana could potentially be a new mosquito control tool effective at reducing disease transmission, although further field work in areas with filariasis transmission should be carried out to verify this. In addition, work targeting malaria vector mosquitoes should be carried out to see if these mosquitoes manifest the same behaviour modification after infection with B. bassiana conidia.
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Affiliation(s)
- Annabel Fv Howard
- Laboratory of Entomology, Wageningen University and Research Centre, P,O, Box 8031, 6700 EH Wageningen, The Netherlands.
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