The Experts below are selected from a list of 24 Experts worldwide ranked by ideXlab platform
Matthew B Thomas - One of the best experts on this subject based on the ideXlab platform.
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development of a model for evaluating the effects of environmental temperature and thermal behaviour on biological control of locusts and grasshoppers using pathogens
Agricultural and Forest Entomology, 2007Co-Authors: Justine I Klass, Simon Blanford, Matthew B ThomasAbstract:Recent years have seen an upsurge in locust and grasshopper populations in many parts of the world. Environmentally sustainable approaches to locust and grass- hopper control may be possible through the use of biopesticides based on ento- mopathogenic fungi. Unfortunately, the performance of these biopesticides is highly variable with environmental temperature and host thermoregulatory behaviour critically determining the pattern and extent of mortality after applica- tions. Here, we present a temperature-dependent model that enables us to predict the field performance of Metarhizium anisopliae var. acridum , the key fungal pathogen used in locust biopesticides. 2 The model was constructed using mortality rate data generated across a range of temperatures in the laboratory and is driven by environmental temperature data linked through host body temperature models. 3 Model predictions were validated against empirical field data obtained for five species, Locustana pardalina , Oedaleus senegalensis , Zonocerus variegatus , Nomadacris septemfasciata and Chortoicetes terminifera. Mortality predictions were accurate to a 2-day error in every 10 days. This level of resolution is satis- factory to guide operational use of the biopesticide. 4 The model was subsequently used for a prospective evaluation of the perform- ance of M. anisopliae var. acridum against two additional pest species, Dociostaurus maroccanus and Calliptamus italicus in Spain. Results suggest that this pathogen would work reasonably well against these species as long as early instars are targeted. 5 The model could provide a useful tool to assist in interpreting effectiveness of con- trol operations, develop improved application strategies to optimize the perform- ance of the biopesticide and identify appropriate target species and environments.
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use of a geographic information system to explore spatial variation in pathogen virulence and the implications for biological control of locusts and grasshoppers
Agricultural and Forest Entomology, 2007Co-Authors: Justine I Klass, Simon Blanford, Matthew B ThomasAbstract:In a previous study, we developed a model to predict the effects of temperature on performance of a fungus-based biopesticide for controlling locusts and grass- hoppers. Currently, the model is limited to predicting rate of mortality after a spray application at site-specific locations. The aim of the present study is to en- hance the utility of this model by linking it with meteorological station data in a geographic information system (GIS) framework to investigate the spatial varia- tion in the performance of the biopesticide. 2 The model provides maps that define spatial variation in pathogen virulence (measured as LT 90 for a treated population) across different regions. The model was used to explore the variation in biopesticide performance against four eco- nomically important pest species: Moroccan locust Dociostaurus maroccanus in Spain; brown locust Locustana pardalina in South Africa; red locust Nomadacris septemfasciata in Zambia and; Senegalese grasshopper Oedaleus senegalensis in Niger. 3 Model outputs for the different species were partially validated against data from field trials. The models provided good estimates of time to 90% mortality for five out of six independent comparisons. There was also good agreement between the spatial model and equivalent output from the site-specific model. 4 Simulations of virulence against N. septemfasciata in Zambia indicated very uni- form, rapid mortality with LT 90 throughout the country generally less than 11 days. Pathogen-induced mortality of O. senegalensis in Niger was predicted to be slightly slower and more variable with mortality fastest in the southern regions ( 30 days in others. 5 The implications of these different patterns of variability for the development of optimum use strategies for the various species and the basic understanding of the ecology and evolution of insect - pathogen interactions are discussed.
Justine I Klass - One of the best experts on this subject based on the ideXlab platform.
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development of a model for evaluating the effects of environmental temperature and thermal behaviour on biological control of locusts and grasshoppers using pathogens
Agricultural and Forest Entomology, 2007Co-Authors: Justine I Klass, Simon Blanford, Matthew B ThomasAbstract:Recent years have seen an upsurge in locust and grasshopper populations in many parts of the world. Environmentally sustainable approaches to locust and grass- hopper control may be possible through the use of biopesticides based on ento- mopathogenic fungi. Unfortunately, the performance of these biopesticides is highly variable with environmental temperature and host thermoregulatory behaviour critically determining the pattern and extent of mortality after applica- tions. Here, we present a temperature-dependent model that enables us to predict the field performance of Metarhizium anisopliae var. acridum , the key fungal pathogen used in locust biopesticides. 2 The model was constructed using mortality rate data generated across a range of temperatures in the laboratory and is driven by environmental temperature data linked through host body temperature models. 3 Model predictions were validated against empirical field data obtained for five species, Locustana pardalina , Oedaleus senegalensis , Zonocerus variegatus , Nomadacris septemfasciata and Chortoicetes terminifera. Mortality predictions were accurate to a 2-day error in every 10 days. This level of resolution is satis- factory to guide operational use of the biopesticide. 4 The model was subsequently used for a prospective evaluation of the perform- ance of M. anisopliae var. acridum against two additional pest species, Dociostaurus maroccanus and Calliptamus italicus in Spain. Results suggest that this pathogen would work reasonably well against these species as long as early instars are targeted. 5 The model could provide a useful tool to assist in interpreting effectiveness of con- trol operations, develop improved application strategies to optimize the perform- ance of the biopesticide and identify appropriate target species and environments.
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use of a geographic information system to explore spatial variation in pathogen virulence and the implications for biological control of locusts and grasshoppers
Agricultural and Forest Entomology, 2007Co-Authors: Justine I Klass, Simon Blanford, Matthew B ThomasAbstract:In a previous study, we developed a model to predict the effects of temperature on performance of a fungus-based biopesticide for controlling locusts and grass- hoppers. Currently, the model is limited to predicting rate of mortality after a spray application at site-specific locations. The aim of the present study is to en- hance the utility of this model by linking it with meteorological station data in a geographic information system (GIS) framework to investigate the spatial varia- tion in the performance of the biopesticide. 2 The model provides maps that define spatial variation in pathogen virulence (measured as LT 90 for a treated population) across different regions. The model was used to explore the variation in biopesticide performance against four eco- nomically important pest species: Moroccan locust Dociostaurus maroccanus in Spain; brown locust Locustana pardalina in South Africa; red locust Nomadacris septemfasciata in Zambia and; Senegalese grasshopper Oedaleus senegalensis in Niger. 3 Model outputs for the different species were partially validated against data from field trials. The models provided good estimates of time to 90% mortality for five out of six independent comparisons. There was also good agreement between the spatial model and equivalent output from the site-specific model. 4 Simulations of virulence against N. septemfasciata in Zambia indicated very uni- form, rapid mortality with LT 90 throughout the country generally less than 11 days. Pathogen-induced mortality of O. senegalensis in Niger was predicted to be slightly slower and more variable with mortality fastest in the southern regions ( 30 days in others. 5 The implications of these different patterns of variability for the development of optimum use strategies for the various species and the basic understanding of the ecology and evolution of insect - pathogen interactions are discussed.
M. B. Thomas - One of the best experts on this subject based on the ideXlab platform.
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Chatham, UK. 18 Development of a Myco-insecticide for Biological Control of Locusts in Southern Africa
2015Co-Authors: M. B. ThomasAbstract:The LUBILOSA (Lutte Biologique contre les Locusts et les Sauteriaux) Programme has been working on the development of a myco-insecticide for the control of locusts and grasshoppers for the past 9 years. The resulting myco-insecticide product (trade name Green MuscleTM) is based on an oil formulation of aerial conidia of the fungal entomopa-thogen, Metarhizium anisopliae var. acridum. Field testing of this myco-insecticide in sou-thern Africa has been conducted in close collaboration with the Locust and Termite Research Division of the Plant Protection Research Institute, South Africa. Trials have been conducted against Brown Locust, Locustana pardalina, in the Karoo region of South Africa and the Red Locust, Nomadacris septemfasciata, in the Buzi outbreak area of Moz-ambique. High (H90%) insect mortalities have been demonstrated following field appli-cations with standard ultra low volume (ULV) spraying equipment normally used in acridid control. Moreover, extensive eco-toxicological work has shown that Green MuscleTM has minimal impact on other non-target species, including other insects, reptiles, birds and mammals. Accordingly, Metarhizium has been recommended by the Food and Agriculture Organisation (FAO) Pesticide Referee Group for locust control in environmen-tally sensitive areas. Most significantly, Green MuscleTM has recently undergone successful registration for locust control in South Africa. This represents a fundamental breakthrough in locust control and creates, for the first time, real opportunities to move away from the use of chemicals towards more integrated control strategies incorporating biological con-trol techniques. This paper presents an overview of the progress of the LUBILOSA Pro-gramme and examines some of the research challenges that remain to fully implement this new technology in the future
Saacks Sharon - One of the best experts on this subject based on the ideXlab platform.
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The structure of hydropyle cells in dormant eggs of the South African brown locust, Locustana pardalina (Walk.)
2008Co-Authors: Saacks SharonAbstract:Water regulation in drought-resistant eggs of the brown locust Locustana pardalina (Walk.) may be mediated by specialised serosal cells in the hydropyle region. These cells are thought to both supply water to the embryo and to waterproof the egg during very dry periods. The characteristics of hydropyle cells in quiescent eggs were examined at intervals during desiccation at 15-22% RH, and again after rehydration. Embryos were pre-catatreptic and any pre-existing diapause condition had terminated. Egg water contents and the sizes of cells and nuclei decrease with desiccation, and increase after rehydration. Deformable cell and nuclear membranes accommodate size changes. Surface microvilli increase in length with rehydration and cytoplasmic vacuoles become larger, indicating absorption of water. Organelle integrity improves upon rehydration while autophagy remains common. Evidence of the production and secretion of a waterproofing protein substance, while expected, was not found. However, electron dense vesicles present at the apical boundaries suggest that the cells may nonetheless produce some substance in that region. Dehydrated and rehydrated cells show signs of desiccation damage, but this does not affect cell functioning as embryos from rehydrated eggs developed to hatching. The results indicate that, in addition to structural protection, hydropyle cells may have molecular protection against desiccation damage, and may be able to undertake limited repair upon rehydration
Cheke Robert - One of the best experts on this subject based on the ideXlab platform.
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Soil moisture assessments for brown locust Locustana pardalina breeding potential using synthetic aperture radar
'SPIE-Intl Soc Optical Eng', 2014Co-Authors: Crooks, William T.s., Cheke RobertAbstract:Synthetic aperture radar (SAR) imagery was collected over a brown locust Locustana pardalina outbreak area to estimate soil moisture relevant to egg development. ERS-2/RadarSat overpasses and field studies enabled parameterization of surface roughness, volumetric soil moisture, soil texture, and vegetation cover. Data were analyzed both when the target area was assessed as nonvegetated and when treated as vegetated. For the former, using the integral equation model (IEM) and soil surface data combined with the sensitivity of the IEM to changes in surface roughness introduced an error of ∼ � 0.06 cm3 cm−3 in volumetric soil moisture. Comparison of the IEM modeling results with backscatter responses from the ERS-2/RadarSat imagery revealed errors as high as �0.14 cm3 cm−3, mostly due to IEM calibration problems and the impact of vegetation. Two modified versions of the water cloud model (WCM) were parameterized, one based on measurements of vegetation moisture and the other on vegetation biomass. A sensitivity analysis of the resulting model revealed a positive relationship between increases in both vegetation biomass and vegetation moisture and the backscatter responses from the ERS-2 and RadarSat sensors. The WCM was able to explain up to 80% of the variability found when the IEM was used alone
