Spatial activity of several species of genera Eristalis and Helophilus

Michael Mikát (1), Jiří Hadrava (1), Zdeněk Janovský (2), Alexandr Kazda (3),
Klára Aldorfová (4), Šárka Mikátová (4) and Jan Martinek (4)

1) Dept. of Zoology, Faculty of Science, Charles University in Prague
2) Dept. of Botany, Faculty of Science, Charles University in Prague
3) Dept. of Algebra, Faculty of Mathematics and Physics, Charles University in Prague
4) Faculty of Science, Charles University in Prague

Spatial activity of hoverflies is important from several points of view, e.g. their colonisation ability, the area from which they can utilise resources or to what distances hoverflies can transport pollen of plants they pollinate. We studied the spatial activity of several large hoverfly species by means of mark-release-recapture method with individual marking in two seasons at two nearby sites. Our sites are species-rich meadows divided by 450 metres of field.

In our poster, we report the results for the four most abundant taxa – Eristalis tenax, E. pertinax, Helophilus trivittatus and E. interruptus + E. arbustorum, which were not in all cases properly distinguished. We also analysed their spatial distribution with respect to host plants they visited.

The species under study did not differ much in the level of their spatial activity. The most individuals were recaptured within the distance of 50 m from the point of their original capture. On the other hand, between 5-10 % of recaptures was at the other locality, i.e. in the distance of 500-700 m. Several individuals were recaptured even within 6 hours of the original capture, which indicates that hoverflies could successfully transfer viable pollen between these sites.

Hoverflies showed preference with respect to their host plants, although they visited more frequently also other plant species in areas of concentration of their preferred host plant species. Thus the plants of the same species experienced a very different pollinator spectrum in different parts of meadow.

Presentováno na 6. symposiu o pestřenkách konaném v Glasgow ve dnech 5.-7.8. 2011.

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