Epidemiology and vectors Vet. Ital., 40 (3), 270-273

Distribution and abundance of imicola, Obsoletus Complex

and Pulicaris Complex (Diptera: ) in Italy

M. Goffredo(1), A. Conte(1) & R. Meiswinkel(1, 2) (1) Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise ‘G. Caporale’, Via Campo Boario, 64100 Teramo, Italy (2) Research affiliate: Agricultural Research Council (ARC)-Onderstepoort Veterinary Institute (OVI), Private Bag X05, Onderstepoort 0110, South Africa

Summary

Between 2000 and 2003, thousands of light-trap collections for Culicoides were made throughout Italy and a detailed distribution map of the primary vector of bluetongue (BT) virus (BTV), C. imicola compiled. In some areas, however, where clinical BT occurred and C. imicola could not be captured, the virus was isolated from biting belonging to the Obsoletus and/or the Pulicaris Complexes. Thus, the distribution and abundance of these two complexes in Italy, as determined from about 3 000 collections, are reported here also and compared to that of C. imicola (from about 24 000 collections). The probable spread of the main vector of BT, C. imicola, into the northern third of Italy, and the widespread prevalence of additional vectors of the Obsoletus and Pulicaris Complexes, indicate nearly all regions of Italy to be at some risk to incursions of BTV. However, these complexes comprise at least six and twelve species, respectively, so precisely which species are able to transmit BTV remains incompletely known.

Keywords

Bluetongue – Culicoides imicola – Italy – Obsoletus Complex – Pulicaris Complex.

Introduction Materials and methods Since 2000, when bluetongue (BT) first affected The collection and the identification of C. imicola and Italy, thousands of light-trap collections have been species of the Obsoletus and Pulicaris Complexes made for Culicoides throughout the country, and were performed in accordance with the protocols detailed distribution maps for C. imicola Kieffer, 1913 developed by the National Reference Centre for compiled (3). During 2000 and 2001 the disease Exotic Diseases (CESME: Centro Studi Malattie occurred in all regions where this vector was Esotiche) (4). The latter two species complexes detected, even in those areas where it was found to comprise at least six and twelve species, respectively; be extremely rare (2, 3). However, in 2002, no these constituent species could not be identified to specimens of C. imicola could be captured in some the species level, and therefore the distribution of areas of Italy where clinical bluetongue (and individual species could not be determined. A more fatalities) occurred amongst sheep. In three of these complete discussion of the of these two outbreaks, BT virus (BTV) serotype 2 and/or BTV species complexes is given elsewhere (6). The map serotype 9 were successfully isolated from biting for C. imicola, the only species of the Imicola midges of the Obsoletus Complex (7); BTV-2 was Complex to occur in the Mediterranean Basin, was isolated also from a species of the Pulicaris Complex compiled from almost 24 000 light-trap collections on the island of Sicily (1). In this study, the authors made over the last four years in 1 533 municipalities. report on the distribution and abundance of The distribution maps for the Obsoletus and the C. imicola, and of the Obsoletus and the Pulicaris Pulicaris Complexes were compiled from Complexes across Italy. approximately 3 000 collections made in 2001-2002 (629 municipalities sampled).

270 Veterinaria Italiana, 40 (3), 2004 Epidemiology and vectors

Results The distributions and abundances of the Obsoletus and Pulicaris Complexes are shown in Figures 1 and 2, respectively; those for C. imicola are shown in Figure 3. These Figures show the log abundances of the largest light-trap collection/municipality and are colour-coded to aid visual interpretation of the maps. These abundances are also graphically depicted (in two forms) in Figure 4, but in this instance the data are combined to produce a single figure/region. All 20 regions of Italy were sampled; these are ranked from north to south (roughly) with the islands of Sicily and Sardinia ranked last.

0 1-9 10-99 100-999 1 000-9 999 10 000-99 999

Figure 2 Maximum light-trap abundances of the Pulicaris Complex collections from 629 municipalities in all regions of Italy, 2000-2002 The complex comprises at least twelve species

The maps (and graphs) show that species of the Obsoletus Complex occur abundantly throughout Italy, whilst species of the Pulicaris Complex tend to 0 be more abundant in the southern regions (Fig. 4). 1-9 10-99 The probable spread of the main vector, C. imicola, 100-999 into the northern third of Italy, and the widespread 1 000-9 999 prevalence of additional vectors of the Obsoletus 10 000-99 999 and Pulicaris Complexes, would seem to indicate Figure 1 that nearly all regions of Italy are at some risk to Maximum light-trap abundances of the Obsoletus incursions by BTV. However, an important caveat is Complex: collections from 629 municipalities in all that the information on the Obsoletus and the regions of Italy, 2000-2002 Pulicaris Complexes remains extremely limited. A The complex comprises at least six species number of species comprise these complexes, and so their distributional and abundance data are difficult to interpret. In addition, it is almost certain that not Discussion all species within these complexes will be able to transmit BTV but precisely which species do, The absence of historical data on the presence of remains unknown. This conflation of data is due C. imicola in Italy before 2000 does not allow us to simply to the fact that these species are extremely establish whether this vector is a recent invader or difficult to identify. Recent molecular analyses not (3). Continuous and thorough monitoring across (combined with morphological studies) (5, 6), have all seasons in all regions has revealed that C. imicola revealed that at least eighteen species of these two occurs beyond the 44th parallel, but at this northern complexes (combined) occur in Italy. It remains to end of its range only one or two specimens are be seen whether the separate mapping of these collected at any one site/season (Fig. 3). Continued species can be achieved in the future using molecular monitoring of such sites is required to establish tools, or whether a greater effort should be made whether C. imicola is spreading northwards and towards locating diagnostic morphological characters whether it is increasing in abundance. easily scored under the dissecting microscope.

Veterinaria Italiana, 40 (3), 2004 271 Epidemiology and vectors

A 5 h 4 3 2

Log midges Log midges 1

(maximum/mont 0 1/2002 2/2002 3/2002 4/2002 5/2002 6/2002 7/2002 8/2002 9/2002 1/2003 2/2003 3/2003 4/2003 5/2003 6/2003 7/2003 8/2003 11/2001 10/2002 11/2002 12/2002 B Month/year

h 3.5 3 2.5 2 1.5 1 0 1-9 Log midges 0.5 10-99 (maximum/mont 0 100-999 1 000-9 999 10 000-99 999 1/2002 2/2002 4/2002 5/2002 6/2002 7/2002 8/2002 9/2002 1/2003 2/2003 3/2003 4/2003 5/2003 6/2003 7/2003 8/2003 9/2003 10/2002 11/2002 12/2002 Month/year Culicoides (total) Culicoides imicola

Figure 3 Maximum light-trap abundances of Culicoides imicola; collections from 1 533 municipalities in all regions of Italy (2000-2003) and seasonal abundances of total Culicoides in the two northernmost collection sites where C. imicola was found in the Provinces of Genoa (A) and Parma (B)

A Piemonte B Veneto Friuli Venezia Giulia 6

Valle d’Aosta s 5 Liguria 4 Lombardia 3 Trentino Alto Adige n Log 2 Emilia Romagna 1 Marche Regio Umbri a 0 Lazio Lazio Sicilia Puglia Molise

Toscana Liguria Umbria Veneto Marche Calabria Toscana Abruzzo Piemonte Basilicata Campania Puglia Sardegna Lombardia

Basilicata Valle d’Aosta Molise Romagna Emilia Trentino Alto Adige Campania Friuli Venezia Giulia Region Abruzzo Culicoides imicola Obsoletus Complex Calabria Pulicaris Complex Sicilia Sardegna

0123456 Log midges Culicoides imicola Obsoletus Complex Pulicaris Complex

Figure 4 Maximum light-trap abundances of each of the species of Culicoides imicola, Obsoletus Complex and Pulicaris Complex captured in the various regions of Italy Log numbers represented as a bar graph (A) and a linear graph (B) ranked roughly from north to south Multiple species comprise the Obsoletus and Pulicaris Complexes, each complex mapped from about 3 000 collections (2000-2002); C. imicola is mapped from about 24 000 catches (2000-2003)

272 Veterinaria Italiana, 40 (3), 2004 Epidemiology and vectors

References 5. Gomulski L.M., Meiswinkel R., Goffredo M., Torti C., Malacrida A.R. & Gasperi G. (2002). – 1. Caracappa S., Torina A., Guercio A., Vitale F., Differenziazione genetica di specie criptiche del Calabrò A., Purpari G., Ferrantelli V., Vitale M. & genere Culicoides, sottogenere Avaritia (Diptera: Mellor P.S. (2003). – Identification of a novel Ceratogonidae), presenti in Italia. In Proc. 63rd bluetongue virus vector species of Culicoides in Sicily. Congresso Nazionale Unione Zoologica Italiana, Vet. Rec., 153, 71-74. Rende, Cosenza, 22-26 September, 103. 2. Goffredo M., Satta G., Torina A., Federico G., 6. Meiswinkel R., Gomulski L.M., Delécolle J.-C., Scaramozzino P., Cafiero M.A., Lelli R. & Goffredo M. & Gasperi G. (2004). – The taxonomy Meiswinkel R. (2001). – The 2000 bluetongue virus of Culicoides vector complexes – unfinished business. (BTV) outbreak in Italy: distribution and abundance In Bluetongue, Part I (N.J. MacLachlan & of the principal vector Culicoides imicola Kieffer. J.E. Pearson, eds). Proc. Third International In Proc. Tenth International Symposium of the Symposium, Taormina, 26-29 October 2003. Vet. American Association of Veterinary Laboratory Ital., 40 (3), 151-159. Diagnosticians (AAVLD), Salsomaggiore, Parma, 4- 7. Savini G., Goffredo M., Monaco F., de Santis P. & 7 July. AAVLD, Ames, 308-309. Meiswinkel R. (2003). – Transmission of bluetongue 3. Goffredo M., Conte A.M., Cocciolito R. & virus in Italy. Vet. Rec., 152 (4), 119. Meiswinkel R. (2003). – The distribution and abundance of Culicoides imicola in Italy. Vet. Ital., 39 (47), 22-32. 4. Goffredo M. & Meiswinkel R. (2004). – Entomological surveillance of bluetongue in Italy: methods of capture, catch analysis and identification of Culicoides biting midges. In Bluetongue, Part I (N.J. MacLachlan & J.E. Pearson, eds). Proc. Third International Symposium, Taormina, 26-29 October 2003. Vet. Ital., 40 (3), 260-265.

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