Study of dipteran insects of genus Culicoides in Greece

The study of Culicoides midges (Diptera: Ceratopogonidae) by scientists around the world is a continuing procedure/ task because of their involvement in the transmission of viral, protozoan and parasitic infections. Nevertheless, the last 30 years due to the comeback and spreading of Bluetongue in the European states / countries, including Greece, scientists from various disciplines acquired an interest for studying the disease. Among them biologists and veterinary entomologists begun studying the vector/ vectors of BTV in their own countries. Despite the fact that the taxonomy of Culicoides is an unfinished business, the most important midges for the transmission of BTV and AHSV in Europe, belong to the Obsoletus, Pulicaris and Imicola complexes. The aim of this thesis was the study of Culicoides species in Greece in order to obtain knowledge about the species distribution, seasonal variation, feeding preference and other parameters useful for their control by the Veterinary Services for the benefit of the farmers and our rural economy. In the first part of this thesis a review of the literature concerning the taxonomic aspects of identification, morphology, biology, dietary habits, breeding sites, impact on their hosts and control of Culicoides along with some basic identification keys. In the second part which comprises our own research, the materials used and methods applied for the collection and analysis of the Culicoides catches are described including the main morphological aspects for their identification. Our results are presented and followed by the discussion and conclusions. Part of this work was under the European Research Project No. QLK2-2000200611 and the Culicoides catches were analysed in the Parasitology Laboratory of the Athens Institute for Infectious and Parasitic Diseases, Ministry for Rural Development and Food. The duration of the project was from 2000 to 2007. In order to organize better the Culicoides trappings the mainland Greece was divided in 59 squares with a 50 km side where two trappings were done from July to November ( Culicoides season ). The Onderstepoort- type electric insect traps were used and the insect catches were forwarded to the lab for analysis. During this study 35 Culicoides species were identified. These are: C. obsoletus, C. scoticus, C. pulicaris, C. punctatus, C. newsteadi, C. circumscriptus, C. fagineus, C. cataneii, C. puncticollis, C. riethi, C. kibunensis, (συν. C. cubitalis), C. festivipennis (συν. C. odibilis), C. parroti, C. maritimus, C. achrayi, C. pallidicornis, C. pictipennis, C. univittatus (συν.C. agathensis), C. fascipennis, C. furcillatus, C. impunctatus, C. imicola, C. odiatus (συν. C. lailae), C. oxystoma, C. saevus, C. kurensis, C. paolae, C. longipennis, C. shaklawensis, C. gejgelensis, C. sejfadinei, C. dzhafarovi, C. denisoni, C. kolymbiensis, C. paradisionensis. From the identified species the following were found for the first time in Greece: C. scoticus, C. riethi, C. pictipennis, C. furcillatus, C. impunctatus, C. paolae. For the first time in mainland Greece were found the following species: C. fascipennis, C. imicola, C. odiatus (συν. C. lailae), C. oxystoma, C. saevus. C. obsoletus was widespread in the country. It seems that this species takes advantage of any type of soil, flora and climate to establish itself. C. punctatus was not found in Crete Island. C. pulicaris despite the fact that was widespread never caught in large numbers. C. imicola, the primary vector of BTV and AHSV in the Mediterannean was not found in Crete and in the western Greece and in mainland Greece during the cold winter months (Dec.- Mar.), on the other hand was found to be active throughout the year in Rhodos island even in very small numbers during the winter.Other main observations were that C. imicola a) was found equally in sheep and in cattle farms. b) was caught in large numbers and c ) we think that the fact that was not present in the western part of the country was due to the high mountain range of Pindos which divides mainland Greece from the north to the south. The palearctic species Culicoides dewulfi of the Obsoletus complex which is incriminated as a vector of the current BTV - 8 epidemic in western - central Europe.Η μελέτη των ειδών του γένους Culicoides απασχολεί τη διεθνή επιστημονική κοινότητα επειδή αυτά μεταδίδουν κυρίως στα ζώα, αλλά και στον άνθρωπο, νοσήματα που οφείλονται σε πρωτόζωα, ιούς και έλμινθες. Τα τελευταία όμως είκοσι και πλέον χρόνια, η εμφάνιση και η εξάπλωση του ιού του καταρροϊκού πυρετού του προβάτου σε διάφορα κράτη της Ευρώπης, μεταξύ των οποίων και η Ελλάδα, οδήγησε το ενδιαφέρον των επιστημόνων στη συστηματική μελέτη των ειδών του γένους Culicoides, τα οποία μεταδίδουν τον ιό του καταρροϊκού πυρετού. Αν και η ταυτοποίηση των ειδών του γένους Culicoides δεν έχει πλήρως ολοκληρωθεί σε πολλά από τα ευρωπαϊκά κράτη, ως παθογόνα είδη μέχρι σήμερα αναφέρονται διεθνώς τα συμπλέγματα (complexes) των C. imicola, C. obsoletus και το είδος C. pulicaris, επειδή μεταδίδουν τον καταρροϊκό πυρετό στα πρόβατα και την αφρικανική πανώλη στα ιπποειδή. Σκοπός της διδακτορικής διατριβής ήταν η μελέτη των ειδών του γένους Culicoides σε όλη την Ελλάδα, έτσι ώστε να αποκτηθεί η γνώση της κατανομής και της εποχιακής εμφάνισης των εντόμων, προκειμένου να ελεγχθεί ο καταρροϊκός πυρετός των προβάτων, προς όφελος της κτηνοτροφίας και της οικονομίας της χώρας μας. Στο πρώτο μέρος της διδακτορικής διατριβής γίνεται μία σύντομη βιβλιογραφική ανασκόπηση της ταξινόμησης και του ιστορικού των ειδών Culicoides που βρέθηκαν ανά τον κόσμο, της μορφολογίας, της βιολογίας, της διαιτητικής συμπεριφοράς, των εστιών αναπαραγωγής, της επίδρασης των Culicoides spp στην υγεία των ζώων και του ανθρώπου και της καταπολέμησης αυτών. Επίσης, στο πρώτο μέρος, αναφέρονται οι κλείδες ταυτοποίησης του γένους Culicoides και των συμπλεγμάτων (complexes) των Culicoides. Στο δεύτερο μέρος, που αποτελεί τη δική μας έρευνα, περιγράφονται τα υλικά που χρησιμοποιήθηκαν και οι μέθοδοι που εφαρμόσθηκαν για τη συλλογή και την επεξεργασία των Culicoides spp., καθώς και τα μορφολογικά γνωρίσματα ταυτοποίησης των ειδών Culicoides. Παρουσιάζονται τα αποτελέσματα της έρευνας και ακολουθεί η συζήτηση των αποτελεσμάτων και η εξαγωγή συμπερασμάτων. Μέρος της διατριβής έγινε στα πλαίσια ερευνητικού ευρωπαϊκού προγράμματος (No. QLK2-2000200611) και η ταυτοποίηση των Culicoides spp. πραγματοποιήθηκε στο Εργαστήριο Παρασιτολογίας του Ινστιτούτου Λοιμωδών και Παρασιτικών Νοσημάτων του Υπουργείου Γεωργίας, Αθήνα. Για τον σκοπό της έρευνας, η οποία έγινε το χρονικό διάστημα 2000 - 2007, η ηπειρωτική Ελλάδα χωρίστηκε σε 59 τετράγωνα πλευράς 50 χιλιομέτρων Χρησιμοποιήθηκαν ηλεκτρικές εντομοπαγίδες του τύπου Onderstepoort για τη συλλογή των εντόμων, τα οποία μετά από επεξεργασία ταυτοποιούνταν

Incriminating bluetongue virus vectors with climate envelope models

1 The spread of vector-borne diseases into new areas, commonly attributed to environmental change or increased trade and travel, could be exacerbated if novel vector species in newly invaded areas spread infection beyond the range of traditional vectors. 2 By analysing the differential degree of overlap between the environmental envelopes for bluetongue, a devastating livestock disease, and its traditional (Afro-Asian) and potential new (Palearctic) midge vectors, we have implicated the latter in the recent dramatic northward spread of this disease into Europe. 3 The traditional vector of bluetongue virus, the Afro-Asian midge Culicoides imicola, was found to occur in warm (annual mean 12–20 °C), thermally stable locations that were dry in summer (< 400 mm precipitation). The Palearctic C. obsoletus and C. pulicaris complexes were both found to occur in cooler (down to 7 °C annual mean), thermally more variable and wetter (up to 700 mm summer precipitation) locations. 4 Of 501 recorded outbreaks from the 1998–2004 bluetongue epidemic in southern Europe, 40% fall outside the climate envelope of C. imicola, but within the species’ envelopes of the C. obsoletus and C. pulicaris complexes. 5 The distribution in multivariate environmental space of bluetongue virus is closer to that of the Palaearctic vectors than it is to that of C. imicola. This suggests that Palearctic vectors now play a substantial role in transmission and have facilitated the spread of bluetongue into cooler, wetter regions of Europe. 6 Synthesis and applications. The risk to Northern Europe now depends on how much of the distributions of the widespread, abundant Palearctic midge vectors (the C. obsoletus and C. pulicaris complexes) bluetongue can occupy, perhaps determined by thermal constraints on viral replication. This was highlighted by the sudden appearance in summer 2006 of bluetongue virus at latitudes of more than 50° North – approximately 6° further North than previous outbreaks in southern Europe. Future surveillance for bluetongue and for related Culicoides-borne pathogens should include studies to record and explain the distributional patterns of all potential Palearctic vector species

Incriminating bluetongue virus vectors with climate envelope models

[eng] Summary 1 The spread of vector‐borne diseases into new areas, commonly attributed to environmental change or increased trade and travel, could be exacerbated if novel vector species in newly invaded areas spread infection beyond the range of traditional vectors. 2 By analysing the differential degree of overlap between the environmental envelopes for bluetongue, a devastating livestock disease, and its traditional (Afro‐Asian) and potential new (Palearctic) midge vectors, we have implicated the latter in the recent dramatic northward spread of this disease into Europe. 3 The traditional vector of bluetongue virus, the Afro‐Asian midge Culicoides imicola, was found to occur in warm (annual mean 12-20 °C), thermally stable locations that were dry in summer (< 400 mm precipitation). The Palearctic C. obsoletus and C. pulicaris complexes were both found to occur in cooler (down to 7 °C annual mean), thermally more variable and wetter (up to 700 mm summer precipitation) locations. 4 Of 501 recorded outbreaks from the 1998-2004 bluetongue epidemic in southern Europe, 40% fall outside the climate envelope of C. imicola, but within the species' envelopes of the C. obsoletus and C. pulicaris complexes. 5 The distribution in multivariate environmental space of bluetongue virus is closer to that of the Palaearctic vectors than it is to that of C. imicola. This suggests that Palearctic vectors now play a substantial role in transmission and have facilitated the spread of bluetongue into cooler, wetter regions of Europe. 6 Synthesis and applications. The risk to Northern Europe now depends on how much of the distributions of the widespread, abundant Palearctic midge vectors (the C. obsoletus and C. pulicaris complexes) bluetongue can occupy, perhaps determined by thermal constraints on viral replication. This was highlighted by the sudden appearance in summer 2006 of bluetongue virus at latitudes of more than 50° North - approximately 6° further North than previous outbreaks in southern Europe. Future surveillance for bluetongue and for related Culicoides‐borne pathogens should include studies to record and explain the distributional patterns of all potential Palearctic vector species

Incriminating bluetongue virus vectors with climate envelope models

1 The spread of vector-borne diseases into new areas, commonly attributed to environmental change or increased trade and travel, could be exacerbated if novel vector species in newly invaded areas spread infection beyond the range of traditional vectors. 2 By analysing the differential degree of overlap between the environmental envelopes for bluetongue, a devastating livestock disease, and its traditional (Afro-Asian) and potential new (Palearctic) midge vectors, we have implicated the latter in the recent dramatic northward spread of this disease into Europe. 3 The traditional vector of bluetongue virus, the Afro-Asian midge Culicoides imicola, was found to occur in warm (annual mean 12–20 °C), thermally stable locations that were dry in summer (&lt; 400 mm precipitation). The Palearctic C. obsoletus and C. pulicaris complexes were both found to occur in cooler (down to 7 °C annual mean), thermally more variable and wetter (up to 700 mm summer precipitation) locations. 4 Of 501 recorded outbreaks from the 1998–2004 bluetongue epidemic in southern Europe, 40% fall outside the climate envelope of C. imicola, but within the species’ envelopes of the C. obsoletus and C. pulicaris complexes. 5 The distribution in multivariate environmental space of bluetongue virus is closer to that of the Palaearctic vectors than it is to that of C. imicola. This suggests that Palearctic vectors now play a substantial role in transmission and have facilitated the spread of bluetongue into cooler, wetter regions of Europe. 6 Synthesis and applications. The risk to Northern Europe now depends on how much of the distributions of the widespread, abundant Palearctic midge vectors (the C. obsoletus and C. pulicaris complexes) bluetongue can occupy, perhaps determined by thermal constraints on viral replication. This was highlighted by the sudden appearance in summer 2006 of bluetongue virus at latitudes of more than 50° North – approximately 6° further North than previous outbreaks in southern Europe. Future surveillance for bluetongue and for related Culicoides-borne pathogens should include studies to record and explain the distributional patterns of all potential Palearctic vector species