Côte d’Ivoire has been the world’s leading producer of cocoa beans for several decades. Apart from this production performance, the quality of the beans, which are mainly exported to the major chocolate-making ...Côte d’Ivoire has been the world’s leading producer of cocoa beans for several decades. Apart from this production performance, the quality of the beans, which are mainly exported to the major chocolate-making countries, presents a quality problem to the point of suffering a discount on the international market. One of these quality problems is the content of ochratoxin A, a mycotoxin produced by fungi. Finally, to verify the level of contamination in beans produced in Côte d’Ivoire, a study was carried out. It consisted of collecting information on fermentation and drying times (The two major post-harvest operations) and collecting beans, which were analyzed by electrophoresis using the High Performance Liquid Chromatography (HPLC) method. The results obtained show ochratoxin A contents of between 0.05 µg/kg and 0.17 µg/kg. The general level of contamination is therefore very low and below the tolerable limit which is 2 µg/kg. In addition, the correlative study between the fermentation and drying times of the beans revealed no significant influence (p < 0.01) of the duration of these operations on the level of ochratoxin A contamination. Major contamination can occur after post-harvest activities carried out by producers. This is certainly due to the development of fungi responsible for the production of ochratoxin A during the period of storage and marketing of cocoa beans in conditions of high humidity in storage enclosures. Producers need to be made more aware of the need to ensure that cocoa beans are properly dried and stored in dry areas to avoid moisture build-up, which is a source of mould growth and ochratoxin A production.展开更多
Production of this crop is experiencing significant challenges, resulting in a decline in seed and fiber quality. To address this challenge, generations of high-performance cotton plants of the Gossypium hirsutum L. s...Production of this crop is experiencing significant challenges, resulting in a decline in seed and fiber quality. To address this challenge, generations of high-performance cotton plants of the Gossypium hirsutum L. species have been developed and are currently being commercialized. This study evaluated the impact of gin types on the agro-industrial quality of cotton in Côte d’Ivoire. To this end, cotton from the G3, R1, and R2 generations was harvested, sampled, and ginned on machines with 10 and 170 saws in the localities of Ouangolodougou, Ferkessédougou, Korhogo, M’Bengué, Boundiali, Séguéla, and Mankono, as well as at the Centre National de Recherche Agronomique CNRA) in Bouaké. The results demonstrated that cotton fibers obtained from ginning on 10-saw machines exhibited superior quality compared to those from 170-saw machines. Fiber length, fiber length uniformity, and short fiber rate exhibited the highest deviations according to gin type. The use of 170-saw gins resulted in a notable decline in quality. Conversely, micronaire index, fiber tenacity and elongation, and reflectance remained consistent across machine types. These results will enable us to more effectively regulate and advise cotton-processing factories, which primarily utilize 170-saw gins to enhance agro-industrial quality in Côte d’Ivoire. Furthermore, these results will assist breeders in incorporating them into their processes to enhance the quality of the varieties they offer to farmers.展开更多
Cellulose synthesis could play an important rolein determining certain aspects of cotton fiberquality,and despite it’s abundance in nature,little is known about the biosynthesis of thispolymer.Recent advances in unde...Cellulose synthesis could play an important rolein determining certain aspects of cotton fiberquality,and despite it’s abundance in nature,little is known about the biosynthesis of thispolymer.Recent advances in understanding thesynthesis of cellulose come from the analysis ofArabidopsis thaliana cellulose-deficient mutants,and the isolation of a number of genes展开更多
The Cotton Programme of CIRAD undertakesdifferent research programs aiming at utilizingDNA molecular markers for an applied molecularbreeding of cotton.These programs cover areasfrom marker-assisted selection for fibe...The Cotton Programme of CIRAD undertakesdifferent research programs aiming at utilizingDNA molecular markers for an applied molecularbreeding of cotton.These programs cover areasfrom marker-assisted selection for fiber qualityto functional genomic study of cotton fiberdevelopment.The present communication willgive an overview of major achievements in thesea reas.展开更多
Variation of soil carbon stock in the cropping systems is an important indicator of their sustainability.The present study was conducted in 2015 and 2018 in seven organic cotton production areas distributed over the S...Variation of soil carbon stock in the cropping systems is an important indicator of their sustainability.The present study was conducted in 2015 and 2018 in seven organic cotton production areas distributed over the Southern and Northern Sudan agro-ecological zones in Burkina Faso.Soil samples were collected in 2015 as baseline and in 2018,after three years of cropping seasons,to determine the variations in carbon stocks in plots under organic farming systems.Surveys were also conducted to understand the fertilization practices implemented by producers during the same period.The results revealed that the recommended fertilization packages were not respected due to low production capacity and under using of organic manure.After three years of cropping in 2018,the deficit of organic restitution has led to a high decline of the soil carbon stocks.This decline was more severe in the 0-10 cm depth in some soils where the decrease in carbon stocks ranged from-4.6 t/ha to-5.5 t/ha.The correlation between soil types and their carbon stocks in the 0-10 cm soil layer was found to be significant(p<0.05)in the Northern Sudan agro-ecological zone with adjusted R2=74%and 54%in 2015 and 2018,respectively,and adjusted R2=56%(2015)and 44%(2018)in the Southern Sudan agro-ecological zone.After three years of organic cotton-based farming,a decrease in the correlation between soil types and their carbon content was observed in the majority of cases.These results show that the process of carbon storage in soil is more influenced by agricultural practices and agro-ecological conditions than by the soil type.展开更多
Background:Since the commercial release of Bt cotton in Burkina Faso in 2009,the issue of seed purity in producers’fields has rarely been addressed in an unbiased and objective manner.The potential for contamination ...Background:Since the commercial release of Bt cotton in Burkina Faso in 2009,the issue of seed purity in producers’fields has rarely been addressed in an unbiased and objective manner.The potential for contamination of conventional seed varieties with Bt traits and the consequent threat to the continuation of organic cotton production has been documented.However,studies are rare on the varietal purity of Bt cotton seeds,despite the implications for the effectiveness and sustainability of their use.This paper compensates for the lack of research on the varietal purity of cotton seeds in Burkina Faso by reporting the results of Enzyme linked immunosorbent assay tests collected in 2015 on samples of both conventional and Bt varieties from 646 fields.Results:According to the conservative criteria used to declare the presence of a Bt gene in a given variety(more than 10%of seeds of conventional variety exhibit Bt traits,and at least 90%of seeds of Bt variety exhibit Bt traits),seed purity was very questionable for both types of variety.For the supposedly conventional variety,the Cry1Ac gene was observed in 63.6%of samples,the Cry2Ab gene was observed in 59.3%of samples,and both genes were detected in 52.2%of the seed samples.Only 29.3%of the seeds that were supposed to be of conventional type contained no Bt genes.Conversely,for the labeled Bt variety,the Cry1Ac gene was found in only 59.6%of samples,the Cry2Ab gene was found in 53.6%of the samples,and both genes were found in 40.4%of the samples.Finally,for the seeds that were supposed to contain both genes(Bollguard 2),both Cry1Ac and Cry2Ab genes were found in only 40.4%of the samples,only one of the genes was found in 32.4%of the samples,and 27.2%of the seeds in the samples contained neither.Two factors are responsible for the severe lack of seed purity.First,conventional varieties are being contaminated with Bt traits because of a failure to revise the seed production scheme in Burkina Faso to prevent cross-pollination.Second,the original Bt seeds provided to Burkina Faso lacked varietal purity.The organic sector plays a very minor role in the cotton sector of Burkina Faso(production of organic cotton totaled 453 t in 2018/2019,out of national cotton production of 183000 t).Nevertheless,the lack of purity in conventional seed varieties is a threat to efforts to expand certified organic cotton production.The poor presence of Bt proteins in supposed Bt varieties undermines their effectiveness in controlling pests and increases the likelihood of the development of resistance among pest populations.Conclusion:Our results show the extent of purity loss when inadequate attention is paid to the preservation of seed purity.Pure conventional seeds could vanish in Burkina Faso,while Bt seeds do not carry the combination of the expected Bt traits.Any country wishing to embark on the use of Bt cotton,or to resume its use,as in the case of Burkina Faso,must first adjust its national seed production scheme to ensure that procedures to preserve varietal purity are enforced.The preservation of varietal purity is necessary to enable the launch or the continuation of identity-cotton production.In addition,the preservation of varietal purity is necessary to ensure the sustainable effectiveness of Bt cotton.In order to ensure that procedures to preserve varietal purity are observed,seed purity must be tested regularly,and test results must be published.展开更多
The study was conducted at the agricultural experimental station of Farako-Bâ, specifically in the Cotton Program. Insects were collected in Farako-Bâ?field and raised in the Cotton Program. Dysder...The study was conducted at the agricultural experimental station of Farako-Bâ, specifically in the Cotton Program. Insects were collected in Farako-Bâ?field and raised in the Cotton Program. Dysdercus voëkeri Schmidt is one of cotton cultivation main pests in Burkina Faso. The control of this devastating cotton bug is based on chemical using. For researching alternative solutions, a part of the biological control method was investigated by using Phonoctonus lutescens which is D. vöelkeri natural enemy, in order to develop a biological control method. To understand the bioecology of P. lutescens, our study has been carried out on this insect under laboratory conditions when it was feed on its prey which is D. voëkeri. The results have demonstrated that the pre-copulation period is 9.33 ± 2.14 days. The oviposition period is 6.97 ± 1.47 days, after which 366.73 ± 27.43 eggs on average are laid with 92.33% ± 4% hatchability. From hatching to adult stage, P. lutescens larvae development goes through five stages with variable durations according to the stage. The results showed that the development cycle lasted 57.23 ± 5.81 days at a temperature of 27.5°C ± 2°C and a relative humidity of 42% ± 3%. Survival rates ranged from 92% to 97.47%. Males and females lived respectively 87.5 ± 27.99 days and 107.97 ± 24.21 days. These results could permit a better use of P. lutescens through a mass rearing and an optimization of D. voëkeri biological control.展开更多
The widespread use of long-lasting insecticidal nets (LLINs) is a major intervention method for malaria control. While coverage of LLINs has increased, there is a need for information on the operational effectiveness ...The widespread use of long-lasting insecticidal nets (LLINs) is a major intervention method for malaria control. While coverage of LLINs has increased, there is a need for information on the operational effectiveness of nets deployed in the field in the context of malaria vector resistance to insecticides used for impregnation. The development of specific anti-malarial biomarkers to assess exposure to mosquito bites is an important development in evaluations. The aim of this study was to characterize the human IgG antibody response to Anopheles gSG6-P1 saliva, a salivary peptide antigen previously shown to be a relevant biomarker of human exposure to Anopheles bites, in order to assess the LLINs under field conditions in areas of low and high vector resistance to insecticides. We analyzed data from 240 randomly selected children ( 0.05). Furthermore, the same finding was observed for antibody expression in children whether or not they used LLINs on the day before the survey (p = 0.7724). Similarly, gender and especially age, major factors of variation in the adaptive immune response, did not have a significant effect on IgG expression.展开更多
Context: Recent publications on WHO recommended methods for estimating the survival of LLINs are good guidelines for assessing the performance of long-lasting insecticidal nets (LLINs). Thus, this field trial study wa...Context: Recent publications on WHO recommended methods for estimating the survival of LLINs are good guidelines for assessing the performance of long-lasting insecticidal nets (LLINs). Thus, this field trial study was undertaken to evaluate the durability of the Yorkool? LN mosquito net distributed during the 2017 campaign in Benin. Methods: The monitoring of Yorkool? LN nets was carried out in two districts (Djougou III and Barienou) in Djougou, department of Donga, northern Benin from October 2017 to March 2019. A representative sample of 250 households that had received the Yorkool? LN polyester LLINs during the 2017 campaign was selected in the rural and urban areas of each district and monitored for 6, 12 and 18 months. An evaluation of the survival of Yorkool? LN nets was conducted based on the rate of loss and physical condition of the surviving nets as measured by the proportional hole index (pHI). Finally, the chemical efficacy of these LLINs during each period was determined using the WHO cone tests. Results: Survival of Yorkool? LN nets was similar in both rural and urban areas, although there was a difference in survival between the 6-month (95.3%), 12-month (89.7%), and 18-month follow-up periods (74.4%). A difference in survival was also observed between the NetCalc model (84%) compared to the Yorkool? LN nets of this study (74.4%). The attrition rate was 29.6% for LLINs at 18 months. Surprisingly, the physical integrity of the LLINs was minimally affected in the municipality. Indeed, the proportion of mosquito nets in good condition without a hole was 51.8% compared to 56.8% with a hole after 18 months. Only 7.8% of the LLINs in the two districts were damaged compared to 2.6% which needed to be replaced. The washing frequency, location of the LLINs and the frequency of use are some factors contributing to the appearance of the holes in LLINs. The bio-efficacy results of LLINs based on the cone test were good with mortality rates of 74%, 66%, 72% and 58% respectively after baseline, 6, 12 and 18 months of use. Conclusions: The observed differences in the survival of Yorkool? LN nets are due to community living conditions and movements and not to the equipment used to manufacture LLINs. However, the estimated median survival has shown that Yorkool? LN nets would have an average lifespan of 2 years 8 months despite their fairly good physical condition. These results may be useful to the National Malaria Control Program (NMCP) during the period of replacement of these nets on the field.展开更多
文摘Côte d’Ivoire has been the world’s leading producer of cocoa beans for several decades. Apart from this production performance, the quality of the beans, which are mainly exported to the major chocolate-making countries, presents a quality problem to the point of suffering a discount on the international market. One of these quality problems is the content of ochratoxin A, a mycotoxin produced by fungi. Finally, to verify the level of contamination in beans produced in Côte d’Ivoire, a study was carried out. It consisted of collecting information on fermentation and drying times (The two major post-harvest operations) and collecting beans, which were analyzed by electrophoresis using the High Performance Liquid Chromatography (HPLC) method. The results obtained show ochratoxin A contents of between 0.05 µg/kg and 0.17 µg/kg. The general level of contamination is therefore very low and below the tolerable limit which is 2 µg/kg. In addition, the correlative study between the fermentation and drying times of the beans revealed no significant influence (p < 0.01) of the duration of these operations on the level of ochratoxin A contamination. Major contamination can occur after post-harvest activities carried out by producers. This is certainly due to the development of fungi responsible for the production of ochratoxin A during the period of storage and marketing of cocoa beans in conditions of high humidity in storage enclosures. Producers need to be made more aware of the need to ensure that cocoa beans are properly dried and stored in dry areas to avoid moisture build-up, which is a source of mould growth and ochratoxin A production.
文摘Production of this crop is experiencing significant challenges, resulting in a decline in seed and fiber quality. To address this challenge, generations of high-performance cotton plants of the Gossypium hirsutum L. species have been developed and are currently being commercialized. This study evaluated the impact of gin types on the agro-industrial quality of cotton in Côte d’Ivoire. To this end, cotton from the G3, R1, and R2 generations was harvested, sampled, and ginned on machines with 10 and 170 saws in the localities of Ouangolodougou, Ferkessédougou, Korhogo, M’Bengué, Boundiali, Séguéla, and Mankono, as well as at the Centre National de Recherche Agronomique CNRA) in Bouaké. The results demonstrated that cotton fibers obtained from ginning on 10-saw machines exhibited superior quality compared to those from 170-saw machines. Fiber length, fiber length uniformity, and short fiber rate exhibited the highest deviations according to gin type. The use of 170-saw gins resulted in a notable decline in quality. Conversely, micronaire index, fiber tenacity and elongation, and reflectance remained consistent across machine types. These results will enable us to more effectively regulate and advise cotton-processing factories, which primarily utilize 170-saw gins to enhance agro-industrial quality in Côte d’Ivoire. Furthermore, these results will assist breeders in incorporating them into their processes to enhance the quality of the varieties they offer to farmers.
文摘Cellulose synthesis could play an important rolein determining certain aspects of cotton fiberquality,and despite it’s abundance in nature,little is known about the biosynthesis of thispolymer.Recent advances in understanding thesynthesis of cellulose come from the analysis ofArabidopsis thaliana cellulose-deficient mutants,and the isolation of a number of genes
文摘The Cotton Programme of CIRAD undertakesdifferent research programs aiming at utilizingDNA molecular markers for an applied molecularbreeding of cotton.These programs cover areasfrom marker-assisted selection for fiber qualityto functional genomic study of cotton fiberdevelopment.The present communication willgive an overview of major achievements in thesea reas.
文摘Variation of soil carbon stock in the cropping systems is an important indicator of their sustainability.The present study was conducted in 2015 and 2018 in seven organic cotton production areas distributed over the Southern and Northern Sudan agro-ecological zones in Burkina Faso.Soil samples were collected in 2015 as baseline and in 2018,after three years of cropping seasons,to determine the variations in carbon stocks in plots under organic farming systems.Surveys were also conducted to understand the fertilization practices implemented by producers during the same period.The results revealed that the recommended fertilization packages were not respected due to low production capacity and under using of organic manure.After three years of cropping in 2018,the deficit of organic restitution has led to a high decline of the soil carbon stocks.This decline was more severe in the 0-10 cm depth in some soils where the decrease in carbon stocks ranged from-4.6 t/ha to-5.5 t/ha.The correlation between soil types and their carbon stocks in the 0-10 cm soil layer was found to be significant(p<0.05)in the Northern Sudan agro-ecological zone with adjusted R2=74%and 54%in 2015 and 2018,respectively,and adjusted R2=56%(2015)and 44%(2018)in the Southern Sudan agro-ecological zone.After three years of organic cotton-based farming,a decrease in the correlation between soil types and their carbon content was observed in the majority of cases.These results show that the process of carbon storage in soil is more influenced by agricultural practices and agro-ecological conditions than by the soil type.
基金The study was implemented on request of the interprofessional body of the cotton sector in Burkina Faso(AICB)with the allocation of a specific fund.
文摘Background:Since the commercial release of Bt cotton in Burkina Faso in 2009,the issue of seed purity in producers’fields has rarely been addressed in an unbiased and objective manner.The potential for contamination of conventional seed varieties with Bt traits and the consequent threat to the continuation of organic cotton production has been documented.However,studies are rare on the varietal purity of Bt cotton seeds,despite the implications for the effectiveness and sustainability of their use.This paper compensates for the lack of research on the varietal purity of cotton seeds in Burkina Faso by reporting the results of Enzyme linked immunosorbent assay tests collected in 2015 on samples of both conventional and Bt varieties from 646 fields.Results:According to the conservative criteria used to declare the presence of a Bt gene in a given variety(more than 10%of seeds of conventional variety exhibit Bt traits,and at least 90%of seeds of Bt variety exhibit Bt traits),seed purity was very questionable for both types of variety.For the supposedly conventional variety,the Cry1Ac gene was observed in 63.6%of samples,the Cry2Ab gene was observed in 59.3%of samples,and both genes were detected in 52.2%of the seed samples.Only 29.3%of the seeds that were supposed to be of conventional type contained no Bt genes.Conversely,for the labeled Bt variety,the Cry1Ac gene was found in only 59.6%of samples,the Cry2Ab gene was found in 53.6%of the samples,and both genes were found in 40.4%of the samples.Finally,for the seeds that were supposed to contain both genes(Bollguard 2),both Cry1Ac and Cry2Ab genes were found in only 40.4%of the samples,only one of the genes was found in 32.4%of the samples,and 27.2%of the seeds in the samples contained neither.Two factors are responsible for the severe lack of seed purity.First,conventional varieties are being contaminated with Bt traits because of a failure to revise the seed production scheme in Burkina Faso to prevent cross-pollination.Second,the original Bt seeds provided to Burkina Faso lacked varietal purity.The organic sector plays a very minor role in the cotton sector of Burkina Faso(production of organic cotton totaled 453 t in 2018/2019,out of national cotton production of 183000 t).Nevertheless,the lack of purity in conventional seed varieties is a threat to efforts to expand certified organic cotton production.The poor presence of Bt proteins in supposed Bt varieties undermines their effectiveness in controlling pests and increases the likelihood of the development of resistance among pest populations.Conclusion:Our results show the extent of purity loss when inadequate attention is paid to the preservation of seed purity.Pure conventional seeds could vanish in Burkina Faso,while Bt seeds do not carry the combination of the expected Bt traits.Any country wishing to embark on the use of Bt cotton,or to resume its use,as in the case of Burkina Faso,must first adjust its national seed production scheme to ensure that procedures to preserve varietal purity are enforced.The preservation of varietal purity is necessary to enable the launch or the continuation of identity-cotton production.In addition,the preservation of varietal purity is necessary to ensure the sustainable effectiveness of Bt cotton.In order to ensure that procedures to preserve varietal purity are observed,seed purity must be tested regularly,and test results must be published.
文摘The study was conducted at the agricultural experimental station of Farako-Bâ, specifically in the Cotton Program. Insects were collected in Farako-Bâ?field and raised in the Cotton Program. Dysdercus voëkeri Schmidt is one of cotton cultivation main pests in Burkina Faso. The control of this devastating cotton bug is based on chemical using. For researching alternative solutions, a part of the biological control method was investigated by using Phonoctonus lutescens which is D. vöelkeri natural enemy, in order to develop a biological control method. To understand the bioecology of P. lutescens, our study has been carried out on this insect under laboratory conditions when it was feed on its prey which is D. voëkeri. The results have demonstrated that the pre-copulation period is 9.33 ± 2.14 days. The oviposition period is 6.97 ± 1.47 days, after which 366.73 ± 27.43 eggs on average are laid with 92.33% ± 4% hatchability. From hatching to adult stage, P. lutescens larvae development goes through five stages with variable durations according to the stage. The results showed that the development cycle lasted 57.23 ± 5.81 days at a temperature of 27.5°C ± 2°C and a relative humidity of 42% ± 3%. Survival rates ranged from 92% to 97.47%. Males and females lived respectively 87.5 ± 27.99 days and 107.97 ± 24.21 days. These results could permit a better use of P. lutescens through a mass rearing and an optimization of D. voëkeri biological control.
文摘The widespread use of long-lasting insecticidal nets (LLINs) is a major intervention method for malaria control. While coverage of LLINs has increased, there is a need for information on the operational effectiveness of nets deployed in the field in the context of malaria vector resistance to insecticides used for impregnation. The development of specific anti-malarial biomarkers to assess exposure to mosquito bites is an important development in evaluations. The aim of this study was to characterize the human IgG antibody response to Anopheles gSG6-P1 saliva, a salivary peptide antigen previously shown to be a relevant biomarker of human exposure to Anopheles bites, in order to assess the LLINs under field conditions in areas of low and high vector resistance to insecticides. We analyzed data from 240 randomly selected children ( 0.05). Furthermore, the same finding was observed for antibody expression in children whether or not they used LLINs on the day before the survey (p = 0.7724). Similarly, gender and especially age, major factors of variation in the adaptive immune response, did not have a significant effect on IgG expression.
基金funded by US Agency for International Development
文摘Context: Recent publications on WHO recommended methods for estimating the survival of LLINs are good guidelines for assessing the performance of long-lasting insecticidal nets (LLINs). Thus, this field trial study was undertaken to evaluate the durability of the Yorkool? LN mosquito net distributed during the 2017 campaign in Benin. Methods: The monitoring of Yorkool? LN nets was carried out in two districts (Djougou III and Barienou) in Djougou, department of Donga, northern Benin from October 2017 to March 2019. A representative sample of 250 households that had received the Yorkool? LN polyester LLINs during the 2017 campaign was selected in the rural and urban areas of each district and monitored for 6, 12 and 18 months. An evaluation of the survival of Yorkool? LN nets was conducted based on the rate of loss and physical condition of the surviving nets as measured by the proportional hole index (pHI). Finally, the chemical efficacy of these LLINs during each period was determined using the WHO cone tests. Results: Survival of Yorkool? LN nets was similar in both rural and urban areas, although there was a difference in survival between the 6-month (95.3%), 12-month (89.7%), and 18-month follow-up periods (74.4%). A difference in survival was also observed between the NetCalc model (84%) compared to the Yorkool? LN nets of this study (74.4%). The attrition rate was 29.6% for LLINs at 18 months. Surprisingly, the physical integrity of the LLINs was minimally affected in the municipality. Indeed, the proportion of mosquito nets in good condition without a hole was 51.8% compared to 56.8% with a hole after 18 months. Only 7.8% of the LLINs in the two districts were damaged compared to 2.6% which needed to be replaced. The washing frequency, location of the LLINs and the frequency of use are some factors contributing to the appearance of the holes in LLINs. The bio-efficacy results of LLINs based on the cone test were good with mortality rates of 74%, 66%, 72% and 58% respectively after baseline, 6, 12 and 18 months of use. Conclusions: The observed differences in the survival of Yorkool? LN nets are due to community living conditions and movements and not to the equipment used to manufacture LLINs. However, the estimated median survival has shown that Yorkool? LN nets would have an average lifespan of 2 years 8 months despite their fairly good physical condition. These results may be useful to the National Malaria Control Program (NMCP) during the period of replacement of these nets on the field.
