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Dearlove EL, Chandler D, Edgington S, Berry SD, Martin G, Svendsen C, Hesketh H. Improved control of Trialeurodes vaporariorum using mixture combinations of entomopathogenic fungi and the chemical insecticide spiromesifen. Sci Rep 2024; 14:15259. [PMID: 38956259 PMCID: PMC11219850 DOI: 10.1038/s41598-024-66051-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 06/26/2024] [Indexed: 07/04/2024] Open
Abstract
Greenhouse whitefly (Trialeurodes vaporariorum) is a major global pest, causing direct damage to plants and transmitting viral plant diseases. Management of T. vaporariorum is problematic because of widespread pesticide resistance, and many greenhouse growers rely on biological control agents to regulate T. vaporariorum populations. However, these are often slow and vary in efficacy, leading to subsequent application of chemical insecticides when pest populations exceed threshold levels. Combining chemical and biological pesticides has great potential but can result in different outcomes, from positive to negative interactions. In this study, we evaluated co-applications of the entomopathogenic fungi (EPF) Beauveria bassiana and Cordyceps farinosa and the chemical insecticide spiromesifen in laboratory bioassays. Complex interactions between the EPFs and insecticide were described using an ecotoxicological mixtures model, the MixTox analysis. Depending on the EPF and chemical concentrations applied, mixtures resulted in additivity, synergism, or antagonism in terms of total whitefly mortality. Combinations of B. bassiana and spiromesifen, compared to single treatments, increased the rate of kill by 5 days. Results indicate the potential for combined applications of EPF and spiromesifen as an effective integrated pest management strategy and demonstrate the applicability of the MixTox model to describe complex mixture interactions.
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Affiliation(s)
- Eleanor L Dearlove
- UK Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK.
- RSK ADAS Ltd. ADAS Gleadthorpe, Meden Vale, Mansfield, NG20 9PD, UK.
| | - David Chandler
- Warwick Crop Centre, School of Life Sciences, Wellesbourne Campus, The University of Warwick, Warwick, UK
| | | | | | | | - Claus Svendsen
- UK Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK
| | - Helen Hesketh
- UK Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK.
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Kallavus T, Kaasik R, Leemet T, Soots K, Soonvald L, Sulg S, Veromann E. Laboratory sprayer for dsRNA application: Design and bioassay validation. MethodsX 2024; 12:102734. [PMID: 38707218 PMCID: PMC11068844 DOI: 10.1016/j.mex.2024.102734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 04/25/2024] [Indexed: 05/07/2024] Open
Abstract
The shortage of commercially available and reliable laboratory spraying equipment for testing different preparations can be a major obstacle to achieve field-comparable results in the laboratory conditions. RNA interference is natural biological process which, when used for plant protection, can be designed method combining sustainability and minimal environmental side effects. Spraying of dsRNA is a field-relevant method that should ensure consistency and repeatability if conducted in laboratory. We built a portable spray device for laboratory use and tested its suitability for dsRNA application. For that, we carried out bioassay on three plant species with different leaf surface textures. DsRNA were detected in all samples 3 days post-treatment indicating its suitability for dsRNA delivery. We built a portable spray device for laboratory use and tested its suitability for dsRNA application. For that, we carried out:•Bioassay on three plant species with different leaf surface textures. DsRNA were detected in all samples 3 days post-treatment indicating its suitability for dsRNA delivery.
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Affiliation(s)
- Triin Kallavus
- Chair of Plant Health, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu 51006, Estonia
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Riina Kaasik
- Chair of Plant Health, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu 51006, Estonia
| | - Tõnu Leemet
- Institute of Forestry and Engineering, Estonian University of Life Sciences, Tartu 51006, Estonia
| | - Kaarel Soots
- Institute of Forestry and Engineering, Estonian University of Life Sciences, Tartu 51006, Estonia
| | - Liina Soonvald
- Chair of Plant Health, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu 51006, Estonia
| | - Silva Sulg
- Chair of Plant Health, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu 51006, Estonia
| | - Eve Veromann
- Chair of Plant Health, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu 51006, Estonia
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Bohatá A, Folorunso EA, Lencová J, Osborne LS, Mraz J. Control of sweet potato whitefly (Bemisia tabaci) using entomopathogenic fungi under optimal and suboptimal relative humidity conditions. PEST MANAGEMENT SCIENCE 2024; 80:1065-1075. [PMID: 37842745 DOI: 10.1002/ps.7837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 09/29/2023] [Accepted: 10/16/2023] [Indexed: 10/17/2023]
Abstract
BACKGROUND Sweet potato whitefly (Bemisia tabaci) is one of the most destructive pests to an extensive range of crops and vegetables. Pesticide-dependent management programs have led to severe health problems, including pesticide poisoning and cancer in human beings, as well as pesticide resistance in insect pests. Entomopathogenic fungi (EPF) are considered safe and highly effective against many pests. Therefore, identifying the pathogenicity and virulence of EPFs against Bemisia tabaci is a valuable addition to the management of their infestations. In this study, we investigated the efficacy of conidia suspensions of Aschersonia aleyrodis, Isaria fumosorosea, Beauveria bassiana, and Akanthomyces muscarius (= Lecanicillium muscarium) against nymphal stages of Bemisia tabaci in cucumber seedlings under both optimal and suboptimal conditions. RESULTS All of the EPFs demonstrated significant ovicidal effects, with the highest cumulative mortalities observed in Aschersonia aleyrodis (96.46%) and I. fumosorosea-treated (94.60%) seedlings against host eggs and crawlers. Similarly, in the L4-instars experiment, Aschersonia aleyrodis and I. fumosorosea were the most efficient, resulting in cumulative mortalities of 94.82% and 94.75%, respectively. However, Bemisia tabaci cumulative mortalities on seedlings treated with Akanthomyces muscarius (78.36%) and Beauveria bassiana (85.90%) were also significantly different from untreated seedlings (7.10%). Under suboptimal relative humidity (RH) conditions (≤ 45% RH), Aschersonia aleyrodis exhibited greater tolerance to harsh conditions, causing a significantly higher infection rate in L1-L2 nymphs (~92%) compared to the approximately 32% infected young nymphs observed in I. fumosorosea-treated seedlings. CONCLUSION All the selected EPF were more effective against the young nymphal instars. Our results also highlight the efficacy of Aschersonia aleyrodis under suboptimal conditions. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Andrea Bohatá
- Department of Plant Protection, Faculty of Agriculture and Technology, University of South Bohemia in Ceske Budejovice, České Budějovice, Czech Republic
| | - Ewumi Azeez Folorunso
- University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Institute of Aquaculture and Protection of Waters, České Budějovice, Czech Republic
| | - Jana Lencová
- Department of Plant Protection, Faculty of Agriculture and Technology, University of South Bohemia in Ceske Budejovice, České Budějovice, Czech Republic
| | - Lance S Osborne
- University of Florida, UF/IFAS Mid-Florida Research & Education Center, Apopka, FL, USA
| | - Jan Mraz
- University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Institute of Aquaculture and Protection of Waters, České Budějovice, Czech Republic
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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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Paradza VM, Khamis FM, Yusuf AA, Subramanian S, Akutse KS. Efficacy of Metarhizium anisopliae and ( E)-2-hexenal combination using autodissemination technology for the management of the adult greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae). FRONTIERS IN INSECT SCIENCE 2022; 2:991336. [PMID: 38646071 PMCID: PMC11027017 DOI: 10.3389/finsc.2022.991336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 08/24/2022] [Indexed: 04/23/2024]
Abstract
The efficiency of an autodissemination technique in controlling adult whiteflies, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae) on tomato, Solunum lycopersicum was investigated with previously identified potent fungal isolates of Metarhizium anisopliae ICIPE 18, ICIPE 62 and ICIPE 69 under screenhouse or semi-field conditions. The autodissemination device was inoculated with dry conidia of the M. anisopliae isolates, while control insects were exposed to a fungus-free device. Sampling for conidia uptake, conidial viability and persistence, and insect mortality was done at 1, 2, 3, 5 and 8 days post-exposure, and collected insects were monitored for mortality over ten days. Overall, mortality was higher in insects exposed to ICIPE 18 (62.8%) and ICIPE 69 (61.8%) than in those exposed to ICIPE 62 (42.6%), with median lethal times, (LT50) ranging between 6.73-8.54 days. The control group recorded the lowest mortality rates (18.9%). A general linear reduction in conidial viability with exposure time was observed, although this was more pronounced with M. anisopliae ICIPE 62. Insects exposed to M. anisopliae ICIPE 69 also recorded the highest conidia uptake, hence selected for further evaluation with a T. vaporariorum attractant volatile organic compound, (E)-2-hexenal. The volatile inhibited fungal germination in laboratory compatibility tests, therefore, spatial separation of M. anisopliae ICIPE 69 and (E)-2-hexenal in the autodissemination device was conducted. The inhibitory effects of the volatile were significantly reduced by spatial separation at a distance of 5 cm between the fungus and the volatile, which was found to be more suitable and chosen for the subsequent experiments. Results showed that (E)-2-hexenal did not influence conidia uptake by the insects, while fungal viability and the subsequent mortality variations were more related to duration of exposure. The fungus-volatile compatibility demonstrated with spatial separation provides a basis for the optimisation of the volatile formulation to achieve better T. vaporariorum suppression with an excellent autodissemination efficiency when used in the management of whiteflies under screenhouse conditions.
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Affiliation(s)
- Vongai M. Paradza
- Plant Health Theme, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
| | - Fathiya M. Khamis
- Plant Health Theme, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Abdullahi A. Yusuf
- Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Hatfield, South Africa
| | - Sevgan Subramanian
- Plant Health Theme, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Komivi S. Akutse
- Plant Health Theme, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
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Idrees A, Qadir ZA, Akutse KS, Afzal A, Hussain M, Islam W, Waqas MS, Bamisile BS, Li J. Effectiveness of Entomopathogenic Fungi on Immature Stages and Feeding Performance of Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) Larvae. INSECTS 2021; 12:1044. [PMID: 34821844 PMCID: PMC8624455 DOI: 10.3390/insects12111044] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 11/17/2021] [Accepted: 11/17/2021] [Indexed: 11/16/2022]
Abstract
Maize is a major staple crop in China, and the sustainable productivity of this primary crop has been recently threatened by fall armyworm (FAW), Spodoptera frugiperda, invasion. The five fungal isolates, Aspergillus sp. BM-3 and SE-2-1, Cladosporium tenuissimum SE-10, Penicillium citrinum CTD-24, and Beauveria bassiana ZK-5 were assessed for their efficacy in causing mortality against first to sixth instar eggs and neonate larvae seven days post-treatment, and their effects on the feeding performance of sixth instar S. frugiperda larvae at 48 h post-treatment at three concentrations (1 × 106, 1 × 107, and 1 × 108 conidia mL-1) were also assessed. The six instar S. frugiperda larvae were not susceptible to the five tested fungal isolates. However, B. bassiana ZK-5 caused the highest egg mortality of 40, 70, and 85.6% at 1 × 106, 1 × 107, and 1 × 108 conidia mL-1, respectively, followed by P. citrinum CTD-24 (30.6, 50, and 75.6%) and C. tenuissimum SE-10 (25.6, 40, and 55.6%). In addition, B. bassiana ZK-5 caused the highest neonate mortality of 54.3% at 1 × 108 conidia mL-1. B. bassiana ZK-5 and P. citrinum CTD-24 caused cumulative mortality, including 93.3 and 83.3% mortality of eggs and neonates, respectively, at 1 × 108 conidia mL-1. Furthermore, B. bassiana ZK-5 reduced the feeding efficacy of first to third instar S. frugiperda larvae by 66.7 to 78.6%, while P. citrinum CTD-24 and C. tenuissimum SE-10 reduced larval feeding by 48.3 to 57.1% at 1 × 108 conidia mL-1. However, these fungal isolates were less potent in reducing the feeding activity of fourth to sixth instar S. frugiperda larvae (>46% with B. bassiana at 48 h post-treatment). The tested fungal isolates could play an essential role as microbial biopesticides in suppressing the S. frugiperda population in China after further investigations on their efficacy are obtained in the field.
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Affiliation(s)
- Atif Idrees
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou 510260, China;
| | - Ziyad Abdul Qadir
- Honeybee Research Institute, National Agricultural Research Centre, Park Road, Islamabad 45500, Pakistan;
- Department of Entomology and Wildlife Ecology, University of Delaware, Newark, DE 19716, USA
| | - Komivi Senyo Akutse
- Plant Health Theme, International Centre of Insect Physiology and Ecology, Nairobi P.O. Box 30772-00100, Kenya;
| | - Ayesha Afzal
- Institute of Molecular Biology and Biotechnology, The University of Lahore, 1-Km Defense Road, Lahore 54000, Pakistan;
| | - Mubasher Hussain
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Engineering Research Center for Mineral oil pesticides, Institute of Zoology, Guangdong Academy of Science, Guangzhou 510260, China;
| | - Waqar Islam
- Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China;
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Muhammad Saad Waqas
- Provincial Key Laboratory for Agricultural Pest Management of Mountainous Regions, and Scientific Observing and Experimental Station of Crop Pest in Guiyang, Institute of Entomology, Ministry of Agricultural and Rural Affairs, Guizhou University, Guiyang 550025, China;
| | - Bamisope Steve Bamisile
- Laboratory of Quarantine and Invasive Pests, Department of Entomology, South China Agricultural University, Guangzhou 510642, China;
| | - Jun Li
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou 510260, China;
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Paradza VM, Khamis FM, Yusuf AA, Subramanian S, Ekesi S, Akutse KS. Endophytic Colonisation of Solanum lycopersicum and Phaseolus vulgaris by Fungal Endophytes Promotes Seedlings Growth and Hampers the Reproductive Traits, Development, and Survival of the Greenhouse Whitefly, Trialeurodes vaporariorum. FRONTIERS IN PLANT SCIENCE 2021; 12:771534. [PMID: 34868170 PMCID: PMC8640138 DOI: 10.3389/fpls.2021.771534] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 10/18/2021] [Indexed: 06/01/2023]
Abstract
In the scope of mitigating the negative impacts of pesticide use and managing greenhouse whiteflies, Trialeurodes vaporariorum sustainably, 16 endophytic fungal isolates from five different genera (Beauveria, Trichoderma, Hypocrea, Bionectria, and Fusarium) were screened for their ability to colonise two preferred host plant species, namely, tomato (Solanum lycopersicum L.) and French bean (Phaseolus vulgaris L.), through seed inoculation. Seven and nine isolates were endophytic to P. vulgaris and S. lycopersicum, respectively, where significant differences in the endophytic colonisation rates were observed among the fungal isolates in P. vulgaris and its plant parts, with a significant interaction between the isolates and plant parts in S. lycopersicum. Hypocrea lixii F3ST1, Trichoderma asperellum M2RT4, Trichoderma atroviride F5S21, and T. harzianum KF2R41 successfully colonised all the plant parts of both hosts and therefore were selected and further evaluated for their endophytic persistence, effect on plant growth, and pathogenicity to T. vaporariorum adults and F1 progeny. The four endophytes remained in both host plants for the 5-week assessment with varied colonisation rates related to the strong interaction with the time, isolates, and plant parts in both hosts. The effect of the same endophytes on the different host growth parameters varied in P. vulgaris and S. lycopersicum, with T. asperellum M2RT4 not boosting the growth in both host plants while T. atroviride F5S21 resulted in enhanced shoot biomass in S. lycopersicum. T. atroviride F5S21 and T. harzianum KF2R41 inoculated S. lycopersicum plants and H. lixii F3ST1, T. asperellum M2RT4, and T. harzianum KF2R41 inoculated P. vulgaris plants had significantly lower oviposition, while nymph development in both hosts was significantly prolonged in all the endophytically-colonised plants. The endophytes H. lixii F3ST1 and T. asperellum M2RT4 significantly reduced the longevity/survival of the exposed T. vaporariorum adults and the progeny in both S. lycopersicum and P. vulgaris. The findings demonstrate the attributes of the various endophytes in host plant growth promotion as well as their effects on the life-history parameters of T. vaporariorum and could consequently be developed as potential endophytic fungal-based biopesticides for the sustainable management of the pest in S. lycopersicum and P. vulgaris cropping systems.
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Affiliation(s)
- Vongai M. Paradza
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
| | - Fathiya M. Khamis
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Abdullahi A. Yusuf
- Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Hatfield, South Africa
| | - Sevgan Subramanian
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Sunday Ekesi
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Komivi S. Akutse
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
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Erdos Z, Chandler D, Bass C, Raymond B. Controlling insecticide resistant clones of the aphid, Myzus persicae, using the entomopathogenic fungus Akanthomyces muscarius: fitness cost of resistance under pathogen challenge. PEST MANAGEMENT SCIENCE 2021; 77:5286-5293. [PMID: 34310830 DOI: 10.1002/ps.6571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Biological control is a cornerstone of integrated pest management and could also play a key role in managing the evolution of insecticide resistance. Ecological theory predicts that the fitness cost of insecticide resistance can be increased under exposure to invertebrate natural enemies or pathogens, and can therefore increase the value of integrating biological control into pest management. In this study of the peach potato aphid, Myzus persicae, we aimed to identify whether insecticide resistance affected fitness and vulnerability of different aphid clones to the entomopathogenic fungus Akanthomyces muscarius. RESULTS Insecticide resistant clones were found to be slightly less susceptible to the pathogen than susceptible clones. However, this pattern could also be explained by the influence of length of laboratory culture, which was longer in susceptible clones and was positively correlated with susceptibility to fungi. Furthermore, resistance status did not affect aphid development time or intrinsic rate of increase of aphids. Finally, in a cage trial the application of fungus did not increase the competitive fitness of insecticide resistant clone 'O'. CONCLUSION We found no fitness cost in reproductive rate or pathogen susceptibility associated with chemical resistance in M. persicae. In contrast, some susceptible clones, particularly those subject to decades of laboratory rearing, showed enhanced susceptibility to a fungal pathogen, but not reduced reproductive fitness, an observation consistent with down-regulation of costly immune functions in culture. Overall, fungal pathogen control is compatible with insecticides and should not increase the selection pressure for resistance of M. persicae to chemical insecticides.
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Affiliation(s)
- Zoltan Erdos
- Centre for Ecology and Conservation, Biosciences, College of Life and Environmental Sciences, University of Exeter, Penryn, Exeter, UK
| | - David Chandler
- School of Life Sciences, The University of Warwick, Coventry, UK
| | - Chris Bass
- Centre for Ecology and Conservation, Biosciences, College of Life and Environmental Sciences, University of Exeter, Penryn, Exeter, UK
| | - Ben Raymond
- Centre for Ecology and Conservation, Biosciences, College of Life and Environmental Sciences, University of Exeter, Penryn, Exeter, UK
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