[Syrphidae] abiotic conditions (e.g. temperature) and hoverfly flight & activity
Fri, 31 Jan 2003 16:21:05 +0100
> Dear Colleagues,
> I wonder if you know references / information on abiotic conditions =
(temperature, humidity, radiation, etc) that may affect flight activity =
of (predaceous) syrphids.
> Last year we screened 30 plants in order to determine floral =
preferences (in 3m2 field plots) in Barcelona (Spain). Observations were =
made between 9 and 12h during may and june (average temp. of 21=BAC), =
but we recorded relatively few flights. Moreover, Episyrphus balteatus =
was almost not recorded although adults were in the area: an =
aphid-infested lettuce field had plenty of E. balteatus larvae. =
Therefore we wonder whether observations should have started earlier in =
> On the other hand, this year we plan to start observations in =
February, so that temperatures early in the day may still be too low and =
we may miss many visits.
> Therefore, we were thinking to start with observations when daily =
temperatures were above a given threshold. Another possibility is to =
record visits on 1 or 2 selected plant species at several hours of the =
day (e.g. 8, 9, ..., 13h); the hour(s) with more visits would then be =
used to determine visit frequencies in all remaninig plant species. The =
hour would change as the season progresses.
> We would like your inputs on these methodologies.
> Best regards,
Miguel Louis Maldonado =20
Dep. Protecci=F3 Vegetal
IRTA - Cabrils
Ctra. de Cabrils, s/n
08348 Cabrils (Barcelona) Spain
Tel: 93 750 75 11
Fax: 93 753 39 54 =20