I

ANNO 4 Numero 2

Mauro Pinzauti [1], Galileo Magnani [2], Gianluca Bedini [1], Ferruccio Filippi [2]

Covering film materials and honey bees (Apis mellifera L.) fligh activity on melon (Cucurbita melo L.) pollination

[1] Dip. Coltivazione e difesa delle specie legnose, sez. Entomologia agraria, Università di Pisa, Pisa, Italia
[2] Dip. Biologia delle piante, sez. Orticultura e floricultura, Università di Pisa, Pisa, Italia

Corresponding author: mpinzaut@agr.unipi.it

Italian commercial interest on orticole tunnel coltures is constantly growing from several years.
On productive purposes the agriculturist must take precautions using two basic agricultural practices: defence from parasites and use of suitable pronubial insects (this second one is necessary in plants that have unisexual flowers and in plants considered strictly entomophilous.

Recently, studies on radiometric and optic characteristics of tunnel’s covering materials, concerning in particular UV radiation, allowed to commercialize films partially or totally UV-proof. The absence of UV radiation by means of new generation covering films has been seen to be in a certain measure responsible of an improvement of the producing process of cultivated plants.
In facts, some mycosis, whom sporulation is supported by UV radiation could at least limit their diffusion if not exposed to this kind of radiation.

Studies on pronubial insects mobility and orientation in this artificial habitats are necessary also to avoid the use of toxic seting chemicals.
Since in a precedent experimentation bumblebees (Bombus terrestris L.) have not shown negative influences in their flight activity in confined habitat, we wanted to verify the pronubial behaviour of honeybees (Apis mellifera L.) on melon in tunnels covered with HALS (Hindered Amine Light Stabilize) films at different formulations.

Apart from well known temperature and humidity problems concerning tunnels, the honeybee different perception of UV radiation has no effects on mobility and pronubial activity of bees inside the tunnels. The plastic films used in our experimentation showed different values of transmittance, particularly in the UV radiation range near to visible light.

Honeybee flight activity inside the tunnel depends on temperature/humidity and on time of the day: inside the tertiary HALS film the number of visits upon the flowers is higher in the less warm part of the day, then the visits decrease to the minimum between 12:00 and 13:00.

The organic nickel stabilized film showed an opposite behaviour: the highest number of flower visits was about at 11:00. Under the HALS-NOR film the number of flower visits was distributed uniformly during all the considered times of the day.