| Sažetak | Glavni cilj ovoga istraživanja bio je utvrditi smjer disperzije komaraca vrste Culex tarsalis i istražiti utjecaj okoliša na tu disperziju.
Culex tarsalis Coquillett najbrojnija je vrsta komaraca na području jugoistočne Kalifornije i glavni ruralni vektor tih prostora. Prenositelj je mnogih virusa, od kojih su najpoznatiji „Western equine encephalomyelitis“ (WEE), „St. Louis encephalitis“ (SLE) i „West Nile“ virus (WNV).
Disperzija komaraca vrste Cx. tarsalis istražena je na širem području naselja Mecca u dolini Coachella Valley u Kaliforniji, u razdoblju od 22. listopada do 6. studenoga 2007. godine „capture-mark-release-recapture“ metodom. Komarci su skupljeni južno od naselja Mecca (23 890), markirani dvjema fluorescentnim bojama (orange i aqua) i pušteni s dvije lokacije: sjeveroistočno i jugozapadno od naselja Mecca. Uzorkovanje markiranih jedinki provedeno je devet puta u dvanaest dana na 40 postaja pravilno raspoređenih na površini od oko 30,6 km2, međusobno udaljenih od 0,2 km do 0,8 km. Korištene su CDC-klopke uz CO2 kao atraktant, ali bez izvora svjetlosti, a postavljene su unutar šest različitih tipova staništa (pustinjsko stanište, plantaže datulja, voćnjaci citrusa, vinogradi, poljoprivredno područje i urbano područje).
Ponovno je uhvaćeno 266 markiranih jedinki vrste Cx. tarsalis (1,11%), od čega 90,22% u prva tri dana uzorkovanja. Više od 50% markiranih jedinki uhvaćeno je u pustinjskom staništu, a tek 3,4% u urbanom staništu. Utvrđeno je kako broj markiranih jedinki značajno raste s porastom udjela pustinje, a značajno opada s porastom udjela urbanog područja u okolici točke hvatanja komaraca, dok o udjelu poljoprivrednih površina, voćnjaka citrusa, vinograda i plantaža datulja ne ovisi statistički značajno.
Na temelju provedene statističke analize dokazano je da nije bilo razlike u disperziji između orange i aqua-komaraca (ovisnoj o udaljenosti od točke puštanja i kutnom otklonu od sjevera).
Zabilježena je značajna tendencija disperzije komaraca u smjeru juga, s obje točke puštanja, vjerojatno stoga jer je ondje većina pogodnih mjesta za hranjenje i polaganje jaja, a relativna vlažnost zraka je u porastu zbog blizine ribnjaka i umjetnih jezera. Moguće je također da je kretanje komaraca usmjeravao vjetar koji je u razdoblju istraživanja bio dominantno sjeverni.
Srednja dnevna prijeđena udaljenost razlikovala se za aqua (0,79 km) i orange (1,06 km) komarce.
Faunističkom obradom ukupnoga broja jedinki (34 708) utvrđeno je osam vrsta komaraca, od kojih je Cx. tarsalis najzastupljenija i čini udio od 86,09%. Ona je jedina eudominantna, eukonstantna i ekskluzivna vrsta u svim zastupljenim staništima. Ustanovljeno je da ukupan sastav populacija komaraca i njihova brojnost koleba u odnosu na tip staništa.
Uspoređujući disperzije ruralnih i poplavnih vrsta komaraca, utvrđeno je da se razlikuju u brzini, ali i da su slične po tome što isu dominantno usmjerene prema urbanim staništima. Spoznaje o kretanju komaraca, dobivene istraživanjima u Kaliforniji i istočnoj Hrvatskoj, mogu unaprijediti programe kontrole komaraca-vektora, uzimajući u obzir okolišne faktore koji utječu na smjer leta ženki komaraca. |
| Sažetak (engleski) | The purpose of the study was to determine direction of mosquito dispersal for species Culex tarsalis and to examine the environmental effect on dispersion.
Culex tarsalis Coquillett is the most abundant mosquito species in southeast California and the primary rural vector of the area. It transmits a wide variety of viruses; the most outstanding are Western equine encephalomyelitis (WEE), St. Louis encephalitis (SLE) and West Nile virus (WNV).
The investigation of dispersal of Cx. tarsalis was performed in the area of Mecca town in Coachella Valley, California, in the period October 22 – November 6, 2007, using capturemark-release-recapture methods. First, the mosquitoes (23,890) were collected at traps placed south from Mecca, then marked with fluorescent dust (orange and aqua) and, finally, released
at two locations: northeast and southwest of small town Mecca.
Recapture was performed nine times in twelve days at 40 CO2 baited CDC-traps without lights and placed across the area (30.6 km2) in six different habitats (desert, date gardens,citrus orchards, vineyards, agricultural area and urban area). The sampling points were between 0.2 km to 0.8 km away from each other.
During the first three days of investigation 90.22% of the total 266 Cx. tarsalis females (1.11%) were recaptured. More than 50% of the marked mosquitoes were collected in the desert while only 3.4% in urban habitat. The analysis indicated that in the surroundings of the trap site the number of marked mosquitoes significantly increases along with the raise in the
portion of the habitat characterised by the desert and significantly decreases with the raise in the portion of the habitat that is urban. However, the portion of agricultural area, citrus orchards, vineyards and date gardens has no statistically significant bearing.
Statistical analyses confirmed that there were no differences in dispersion between orange and aqua mosquitoes (dependent on the distance from the release point and on the angle of deflection from the North).
A significant tendency of mosquito dispersal to the south was recorded for both release points, probably due to the most favourable feeding places and oviposition sites and potentially increase humidity caused by the vicinity of large ponds. Furthermore, there is a possibility that the wind, predominantly northern during the investigation period, had an
influence on mosquito dispersal direction. The mean distance travelled was different for aqua (0.79 km) and orange (1.06 km) mosquitoes. Eight species emerged through faunistic analysis of the adult mosquitoes captured (34,708),
the most common being Cx. tarsalis (86.09%). This is the only eudominant, euconstant and exclusive species in all habitats. It was determined that mosquito population structure and mosquito abundance oscillate in accordance with the habitat type.
The comparison of dispersion of rural and floodwater mosquito species identified differences in dispersal rates. However, similarities were detected with regard to the direction (the prevailing direction was away from urban habitats). Knowledge of mosquito movement obtained by the investigations in California and Eastern Croatia can improve mosquito and vector control programs by taking into account environmental factors that influence female mosquito flight direction. |
