This paper describes a decision-support scheme (DSS) for mapping the area where economically impo... more This paper describes a decision-support scheme (DSS) for mapping the area where economically important loss is likely to occur (the endangered area). It has been designed by the PRATIQUE project to help pest risk analysts address the numerous risk mapping challenges and decide on the most suitable methods to follow. The introduction to the DSS indicates the time and expertise that is needed, the data requirements and the situations when mapping the endangered areas is most useful. The DSS itself has four stages. In stage 1, the key factors that influence the endangered area are identified, the data are assembled and, where appropriate, maps of the key factors are produced listing any significant assumptions. In stage 2, methods for combining these maps to identify the area of potential establishment and the area at highest risk from pest impacts are described, documenting any assumptions and combination rules utilised. When possible and appropriate, Stage 3 can then be followed to show whether economic loss will occur in the area at highest risk and to identify the endangered area. As required, Stage 4, described elsewhere, provides techniques for producing a dynamic picture of the invasion process using a suite of spread models. To illustrate how the DSS functions, a maize pest, Diabrotica virgifera virgifera, and a freshwater invasive alien plant, Eichhornia crassipes, have been used as examples.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
An assessment of the risk of introduction and spread of Heterodera zeae on the territory of Bulga... more An assessment of the risk of introduction and spread of Heterodera zeae on the territory of Bulgaria was prepared in connection to the report of the pest from Paleochori Kavallas, Greece, close to the Bulgarian border. H. zeae was described in the early 70s from India. The species is currently distributed in ten countries on four continents: Asia, Africa, Europe and North America. H. zeae is considered as one of the most economically important nematodes on corn and cereals in India and Pakistan. Its development and reproduction are favored by relatively high soil temperatures in the interval of 27 - 36oС but the cysts remain viable for up to three years at 2oС and successfully survive at -18oС for 7 months. The known host range of the parasite consists exclusively of representatives of family Poaceae, which are cultivated from seeds and therefore are not traded internationally as planting material. Nevertheless, the nematode has been established in the rizosphere of non-host crops.
Pest Risk Analyses (PRAs) are conducted worldwide to decide whether and how exotic plant pests sh... more Pest Risk Analyses (PRAs) are conducted worldwide to decide whether and how exotic plant pests should be regulated to prevent invasion. There is an increasing demand for science-based risk mapping in PRA. Spread plays a key role in determining the potential distribution of pests, but there is no suitable spread modelling tool available for pest risk analysts. Existing models are species specific, biologically and technically complex, and data hungry. Here we present a set of four simple and generic spread models that can be parameterised with limited data. Simulations with these models generate maps of the potential expansion of an invasive species at continental scale. The models have one to three biological parameters. They differ in whether they treat spatial processes implicitly or explicitly, and in whether they consider pest density or pest presence/absence only. The four models represent four complementary perspectives on the process of invasion and, because they have different initial conditions, they can be considered as alternative scenarios. All models take into account habitat distribution and climate. We present an application of each of the four models to the western corn rootworm, Diabrotica virgifera virgifera, using historic data on its spread in Europe. Further tests as proof of concept were conducted with a broad range of taxa (insects, nematodes, plants, and plant pathogens). Pest risk analysts, the intended model users, found the model outputs to be generally credible and useful. The estimation of parameters from data requires insights into population dynamics theory, and this requires guidance. If used appropriately, these generic spread models provide a transparent and objective tool for evaluating the potential spread of pests in PRAs. Further work is needed to validate models, build familiarity in the user community and create a database of species parameters to help realize their potential in PRA practice.
This paper describes a decision-support scheme (DSS) for mapping the area where economically impo... more This paper describes a decision-support scheme (DSS) for mapping the area where economically important loss is likely to occur (the endangered area). It has been designed by the PRATIQUE project to help pest risk analysts address the numerous risk mapping challenges and decide on the most suitable methods to follow. The introduction to the DSS indicates the time and expertise that is needed, the data requirements and the situations when mapping the endangered areas is most useful. The DSS itself has four stages. In stage 1, the key factors that influence the endangered area are identified, the data are assembled and, where appropriate, maps of the key factors are produced listing any significant assumptions. In stage 2, methods for combining these maps to identify the area of potential establishment and the area at highest risk from pest impacts are described, documenting any assumptions and combination rules utilised. When possible and appropriate, Stage 3 can then be followed to show whether economic loss will occur in the area at highest risk and to identify the endangered area. As required, Stage 4, described elsewhere, provides techniques for producing a dynamic picture of the invasion process using a suite of spread models. To illustrate how the DSS functions, a maize pest, Diabrotica virgifera virgifera, and a freshwater invasive alien plant, Eichhornia crassipes, have been used as examples.
KARADJOVA, O., Z. ILIEVA, E. PETROVA and V. KRUMOV. Heterodera zeae Koshy, Swarup and Sethi, 1971... more KARADJOVA, O., Z. ILIEVA, E. PETROVA and V. KRUMOV. Heterodera zeae Koshy, Swarup and Sethi, 1971 (Heteroderidae): probability of introduction on cereals in Bulgaria. Bulg. J. Agric. Sci., 21: 969–981 The present paper assesses the probability of entry and establishment of the corn cyst nematode Heterodera zeae in Bulgaria. The species is currently distributed in ten countries in Asia, Africa, Europe and North America and is one of the most economically important pests on corn and other cereal crops in India and Pakistan. In 2009, H. zeae was established in close proximity to the Bulgarian border with Greece (Kavala). Three main pathways of entry of H. zeae in the country have been considered. The highest risk is associated with the import of bulbs, rhizomes, tubers and other underground plant parts with attached soil, intended for direct consumption and processing from countries where the pest is distributed. For this pathway, the probability of entry has been assessed as moderate....
EFSA guidance regarding pest risk assessment previously identified limitations within a generic q... more EFSA guidance regarding pest risk assessment previously identified limitations within a generic qualitative risk assessment scheme published to support EU plant health decision making. In seeking to develop methods to overcome the limitations, we report results of a multiphase project where five test risk assessment methods were applied to Anoplophora glabripennis, Candidatus Phytoplasma pyri, Guignardia citricarpa, Meloidogyne chitwoodi, and Xanthomonas citri strains causing citrus bacterial canker. Teams of pest risk assessors applied the methods to the pests and compared methods in relation to EFSA PLH needs. The most promising method was then revised to incorporate desirable features from the other methods and tested on five more case study pests; Acidovorax citrulli, Ca.P. mali, Ca. P. prunorum, M. Fallax and Mycosphaerella dearnessii. In addition the risk assessment method that emerged from the EU funded project PRATIQUE was adapted to better suit EFSA needs and also tested on the second set of pests. Comprehensive datasheets on each pest were compiled to support the risk assessments. Datasheets included information that emerged from individual pest questionnaires distributed to the National Plant Protection Organisations of each EU Member State. Short term experimental studies were conducted to reduce uncertainty regarding survival and infectivity of the root-knot nematodes in the absence of host plants. Small scale experiments also clarified the role of vectors in the spread of Ca. Phytoplasma prunorum, proving that psyllids acquired the pathogen from wild Prunus sp. and transmitted it to orchards. Results from both sets of studies better informed the respective risk assessments and reduced some uncertainties although significant uncertainties still remain elsewhere within assessments. A novel method to determine an index of individual risk components, e.g. likelihood of entry, was developed. The performance of risk reduction options was evaluated by repeating assessments considering scenarios with and without risk reduction options in place. (Resume d'auteur)
The nematode fauna in an old raspberry plantation was studied in 28 bulk samples. Eleven species ... more The nematode fauna in an old raspberry plantation was studied in 28 bulk samples. Eleven species of five families of Dorylaimida were found. The occurrence and relative abundance of each species were calculated and the distribution of the species in Bulgaria was summarized. The most abundant species of the studied families are Aporcella simplex and E. subdigitalis. Discolaimoides bulbiferus and Crassolabium cf cylindricum are new geographical records for Bulgaria and Арorcelaimus cf americanus, Discolaimus agricolus and Eudorylaimus subdigitalis for the Balkan Peninsula. Morphometrics and microphotography of our populations are presented.
Summary. Male specimens of Pungentus silvestris (de Man, 1912) Coomans et Geraert, 1962 are repor... more Summary. Male specimens of Pungentus silvestris (de Man, 1912) Coomans et Geraert, 1962 are reported for the first time. They were found in three different places in Bulgaria. A short description and illustrations together with morphometric characteristics of female ...
Species of the genus Hemicycliophora de Man, 1921 are not very often reported from natural or agr... more Species of the genus Hemicycliophora de Man, 1921 are not very often reported from natural or agricultural areas of Bulgaria. Hemicycliophora labiata Colbran 1920 was reported from the region of Blagoevgrad (Choleva-Abadjieva and Budurova 1983) but in later studies no other records of the genus were found. We isolated specimens of Hemicycliophora from intensively irrigated patches with wilt and postponed plants from a strawberry field in the Plovdiv region (30.10.2015) and a golf course in the Dobrich region (27.07.2019). Nematodes were isolated by Oostenbrink elutriator followed by 72 h exposition, killed by gently heating at temperature of 55oC and fixed in FAA. Fifty two specimens from Plovdiv region and 31 specimens from Dobrich were mounted in glycerol after Seinhorst (1959). The specimens from Plovdiv were identified as H. poranga Monteiro & Lordello, 1978. Ther morphology is similar to those of the population described from Pistachino, Italy (Subbotin et al. 2017). According ...
The Mediterranean fruit fly Ceratitis capitata (Wiedemann, 1824) (Diptera: Tephritidae) is consid... more The Mediterranean fruit fly Ceratitis capitata (Wiedemann, 1824) (Diptera: Tephritidae) is considered to be one of the world’s most destructive fruit pests because of its global distribution, wide host range and rapid dispersal. In the period 1956–2006, transient populations of the pest have been reported regularly in Bulgaria. The Bulgarian Food Safety Agency (BFSA) initiated monitoring of C. capitata in 15 regions of the country. The surveys were conducted during the period 2013–2018, using Jackson traps with attractant trimedlure and Tephri traps with Biolure. The presence of adults of C. capitata was confirmed in peach, apple and mixed orchards, as well as in private yards at five locations in southern and south-eastern Bulgaria: Blagoevgrad, Kyustendil, Pazardzhik, Plovdiv and Sliven. The results from the five-year monitoring showed a variable abundance of C. capitata adults captured in different years and localities. The highest mean captures were recorded in 2014 (195) and 20...
581 species of plant parasitic and free-living soil nematodes have been reported in systematic or... more 581 species of plant parasitic and free-living soil nematodes have been reported in systematic order from Bulgaria till 1996.
New geographic records of Dorylaimellus demani Goodey, 1963; Pungentus silvestris (de Man, 1880);... more New geographic records of Dorylaimellus demani Goodey, 1963; Pungentus silvestris (de Man, 1880); Enchodellus magnificus (Altherr, 1952); Tylencholaimus airolensis Loof et Jairajpuri, 1968; Tylencholaimus minutes Vinciguerra 1986; Eudorilaimus pseudocarteri Loof, 1975 were made from the area of biospherical reserve Parangalitsa, Southwestern Bulgaria. Short descriptions of the localities and found specimens were given.
Three species of the family Pratylenchidae (Pratylenchus crenatus Loof, 1960; Pretylenchoides rit... more Three species of the family Pratylenchidae (Pratylenchus crenatus Loof, 1960; Pretylenchoides ritteri Sher, 1970 and P. ivanovae Ryss, 1980) were found in biospherical reserve Parangalitsa. Morphological descriptions and figures of found specimens are given. Species Pratylenchoides katalani Katala-Gateva et Alexiev, 1989 described from the same locality was synonymized with Pratylenchoides ivanovae.
This paper describes a decision-support scheme (DSS) for mapping the area where economically impo... more This paper describes a decision-support scheme (DSS) for mapping the area where economically important loss is likely to occur (the endangered area). It has been designed by the PRATIQUE project to help pest risk analysts address the numerous risk mapping challenges and decide on the most suitable methods to follow. The introduction to the DSS indicates the time and expertise that is needed, the data requirements and the situations when mapping the endangered areas is most useful. The DSS itself has four stages. In stage 1, the key factors that influence the endangered area are identified, the data are assembled and, where appropriate, maps of the key factors are produced listing any significant assumptions. In stage 2, methods for combining these maps to identify the area of potential establishment and the area at highest risk from pest impacts are described, documenting any assumptions and combination rules utilised. When possible and appropriate, Stage 3 can then be followed to show whether economic loss will occur in the area at highest risk and to identify the endangered area. As required, Stage 4, described elsewhere, provides techniques for producing a dynamic picture of the invasion process using a suite of spread models. To illustrate how the DSS functions, a maize pest, Diabrotica virgifera virgifera, and a freshwater invasive alien plant, Eichhornia crassipes, have been used as examples.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
An assessment of the risk of introduction and spread of Heterodera zeae on the territory of Bulga... more An assessment of the risk of introduction and spread of Heterodera zeae on the territory of Bulgaria was prepared in connection to the report of the pest from Paleochori Kavallas, Greece, close to the Bulgarian border. H. zeae was described in the early 70s from India. The species is currently distributed in ten countries on four continents: Asia, Africa, Europe and North America. H. zeae is considered as one of the most economically important nematodes on corn and cereals in India and Pakistan. Its development and reproduction are favored by relatively high soil temperatures in the interval of 27 - 36oС but the cysts remain viable for up to three years at 2oС and successfully survive at -18oС for 7 months. The known host range of the parasite consists exclusively of representatives of family Poaceae, which are cultivated from seeds and therefore are not traded internationally as planting material. Nevertheless, the nematode has been established in the rizosphere of non-host crops.
Pest Risk Analyses (PRAs) are conducted worldwide to decide whether and how exotic plant pests sh... more Pest Risk Analyses (PRAs) are conducted worldwide to decide whether and how exotic plant pests should be regulated to prevent invasion. There is an increasing demand for science-based risk mapping in PRA. Spread plays a key role in determining the potential distribution of pests, but there is no suitable spread modelling tool available for pest risk analysts. Existing models are species specific, biologically and technically complex, and data hungry. Here we present a set of four simple and generic spread models that can be parameterised with limited data. Simulations with these models generate maps of the potential expansion of an invasive species at continental scale. The models have one to three biological parameters. They differ in whether they treat spatial processes implicitly or explicitly, and in whether they consider pest density or pest presence/absence only. The four models represent four complementary perspectives on the process of invasion and, because they have different initial conditions, they can be considered as alternative scenarios. All models take into account habitat distribution and climate. We present an application of each of the four models to the western corn rootworm, Diabrotica virgifera virgifera, using historic data on its spread in Europe. Further tests as proof of concept were conducted with a broad range of taxa (insects, nematodes, plants, and plant pathogens). Pest risk analysts, the intended model users, found the model outputs to be generally credible and useful. The estimation of parameters from data requires insights into population dynamics theory, and this requires guidance. If used appropriately, these generic spread models provide a transparent and objective tool for evaluating the potential spread of pests in PRAs. Further work is needed to validate models, build familiarity in the user community and create a database of species parameters to help realize their potential in PRA practice.
This paper describes a decision-support scheme (DSS) for mapping the area where economically impo... more This paper describes a decision-support scheme (DSS) for mapping the area where economically important loss is likely to occur (the endangered area). It has been designed by the PRATIQUE project to help pest risk analysts address the numerous risk mapping challenges and decide on the most suitable methods to follow. The introduction to the DSS indicates the time and expertise that is needed, the data requirements and the situations when mapping the endangered areas is most useful. The DSS itself has four stages. In stage 1, the key factors that influence the endangered area are identified, the data are assembled and, where appropriate, maps of the key factors are produced listing any significant assumptions. In stage 2, methods for combining these maps to identify the area of potential establishment and the area at highest risk from pest impacts are described, documenting any assumptions and combination rules utilised. When possible and appropriate, Stage 3 can then be followed to show whether economic loss will occur in the area at highest risk and to identify the endangered area. As required, Stage 4, described elsewhere, provides techniques for producing a dynamic picture of the invasion process using a suite of spread models. To illustrate how the DSS functions, a maize pest, Diabrotica virgifera virgifera, and a freshwater invasive alien plant, Eichhornia crassipes, have been used as examples.
KARADJOVA, O., Z. ILIEVA, E. PETROVA and V. KRUMOV. Heterodera zeae Koshy, Swarup and Sethi, 1971... more KARADJOVA, O., Z. ILIEVA, E. PETROVA and V. KRUMOV. Heterodera zeae Koshy, Swarup and Sethi, 1971 (Heteroderidae): probability of introduction on cereals in Bulgaria. Bulg. J. Agric. Sci., 21: 969–981 The present paper assesses the probability of entry and establishment of the corn cyst nematode Heterodera zeae in Bulgaria. The species is currently distributed in ten countries in Asia, Africa, Europe and North America and is one of the most economically important pests on corn and other cereal crops in India and Pakistan. In 2009, H. zeae was established in close proximity to the Bulgarian border with Greece (Kavala). Three main pathways of entry of H. zeae in the country have been considered. The highest risk is associated with the import of bulbs, rhizomes, tubers and other underground plant parts with attached soil, intended for direct consumption and processing from countries where the pest is distributed. For this pathway, the probability of entry has been assessed as moderate....
EFSA guidance regarding pest risk assessment previously identified limitations within a generic q... more EFSA guidance regarding pest risk assessment previously identified limitations within a generic qualitative risk assessment scheme published to support EU plant health decision making. In seeking to develop methods to overcome the limitations, we report results of a multiphase project where five test risk assessment methods were applied to Anoplophora glabripennis, Candidatus Phytoplasma pyri, Guignardia citricarpa, Meloidogyne chitwoodi, and Xanthomonas citri strains causing citrus bacterial canker. Teams of pest risk assessors applied the methods to the pests and compared methods in relation to EFSA PLH needs. The most promising method was then revised to incorporate desirable features from the other methods and tested on five more case study pests; Acidovorax citrulli, Ca.P. mali, Ca. P. prunorum, M. Fallax and Mycosphaerella dearnessii. In addition the risk assessment method that emerged from the EU funded project PRATIQUE was adapted to better suit EFSA needs and also tested on the second set of pests. Comprehensive datasheets on each pest were compiled to support the risk assessments. Datasheets included information that emerged from individual pest questionnaires distributed to the National Plant Protection Organisations of each EU Member State. Short term experimental studies were conducted to reduce uncertainty regarding survival and infectivity of the root-knot nematodes in the absence of host plants. Small scale experiments also clarified the role of vectors in the spread of Ca. Phytoplasma prunorum, proving that psyllids acquired the pathogen from wild Prunus sp. and transmitted it to orchards. Results from both sets of studies better informed the respective risk assessments and reduced some uncertainties although significant uncertainties still remain elsewhere within assessments. A novel method to determine an index of individual risk components, e.g. likelihood of entry, was developed. The performance of risk reduction options was evaluated by repeating assessments considering scenarios with and without risk reduction options in place. (Resume d'auteur)
The nematode fauna in an old raspberry plantation was studied in 28 bulk samples. Eleven species ... more The nematode fauna in an old raspberry plantation was studied in 28 bulk samples. Eleven species of five families of Dorylaimida were found. The occurrence and relative abundance of each species were calculated and the distribution of the species in Bulgaria was summarized. The most abundant species of the studied families are Aporcella simplex and E. subdigitalis. Discolaimoides bulbiferus and Crassolabium cf cylindricum are new geographical records for Bulgaria and Арorcelaimus cf americanus, Discolaimus agricolus and Eudorylaimus subdigitalis for the Balkan Peninsula. Morphometrics and microphotography of our populations are presented.
Summary. Male specimens of Pungentus silvestris (de Man, 1912) Coomans et Geraert, 1962 are repor... more Summary. Male specimens of Pungentus silvestris (de Man, 1912) Coomans et Geraert, 1962 are reported for the first time. They were found in three different places in Bulgaria. A short description and illustrations together with morphometric characteristics of female ...
Species of the genus Hemicycliophora de Man, 1921 are not very often reported from natural or agr... more Species of the genus Hemicycliophora de Man, 1921 are not very often reported from natural or agricultural areas of Bulgaria. Hemicycliophora labiata Colbran 1920 was reported from the region of Blagoevgrad (Choleva-Abadjieva and Budurova 1983) but in later studies no other records of the genus were found. We isolated specimens of Hemicycliophora from intensively irrigated patches with wilt and postponed plants from a strawberry field in the Plovdiv region (30.10.2015) and a golf course in the Dobrich region (27.07.2019). Nematodes were isolated by Oostenbrink elutriator followed by 72 h exposition, killed by gently heating at temperature of 55oC and fixed in FAA. Fifty two specimens from Plovdiv region and 31 specimens from Dobrich were mounted in glycerol after Seinhorst (1959). The specimens from Plovdiv were identified as H. poranga Monteiro & Lordello, 1978. Ther morphology is similar to those of the population described from Pistachino, Italy (Subbotin et al. 2017). According ...
The Mediterranean fruit fly Ceratitis capitata (Wiedemann, 1824) (Diptera: Tephritidae) is consid... more The Mediterranean fruit fly Ceratitis capitata (Wiedemann, 1824) (Diptera: Tephritidae) is considered to be one of the world’s most destructive fruit pests because of its global distribution, wide host range and rapid dispersal. In the period 1956–2006, transient populations of the pest have been reported regularly in Bulgaria. The Bulgarian Food Safety Agency (BFSA) initiated monitoring of C. capitata in 15 regions of the country. The surveys were conducted during the period 2013–2018, using Jackson traps with attractant trimedlure and Tephri traps with Biolure. The presence of adults of C. capitata was confirmed in peach, apple and mixed orchards, as well as in private yards at five locations in southern and south-eastern Bulgaria: Blagoevgrad, Kyustendil, Pazardzhik, Plovdiv and Sliven. The results from the five-year monitoring showed a variable abundance of C. capitata adults captured in different years and localities. The highest mean captures were recorded in 2014 (195) and 20...
581 species of plant parasitic and free-living soil nematodes have been reported in systematic or... more 581 species of plant parasitic and free-living soil nematodes have been reported in systematic order from Bulgaria till 1996.
New geographic records of Dorylaimellus demani Goodey, 1963; Pungentus silvestris (de Man, 1880);... more New geographic records of Dorylaimellus demani Goodey, 1963; Pungentus silvestris (de Man, 1880); Enchodellus magnificus (Altherr, 1952); Tylencholaimus airolensis Loof et Jairajpuri, 1968; Tylencholaimus minutes Vinciguerra 1986; Eudorilaimus pseudocarteri Loof, 1975 were made from the area of biospherical reserve Parangalitsa, Southwestern Bulgaria. Short descriptions of the localities and found specimens were given.
Three species of the family Pratylenchidae (Pratylenchus crenatus Loof, 1960; Pretylenchoides rit... more Three species of the family Pratylenchidae (Pratylenchus crenatus Loof, 1960; Pretylenchoides ritteri Sher, 1970 and P. ivanovae Ryss, 1980) were found in biospherical reserve Parangalitsa. Morphological descriptions and figures of found specimens are given. Species Pratylenchoides katalani Katala-Gateva et Alexiev, 1989 described from the same locality was synonymized with Pratylenchoides ivanovae.
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