Citronella (Cymbopogon nardus), oregano (Origanum vulgare) and
rosemary (Rosmarinus officinalis) essential oils (EO) were purchased
from Gutiérrez SAS Matières Premières Essentielles (Grasse Cedex,
France). Such oils are GRAS (Generally Recognized as Safe) according
to FDA (21CFR182.20). In the following the gross composition of tested
essential oils is reported:
Citronella oil. FDA: 182.20. Citronellal 35 ÷ 40%; geraniol
25 ÷ 30%; citronellol 15 ÷ 20%, D-limonene 5 ÷ 10%; linalool
0 ÷ 5%; farnesol 0 ÷ 5%
Origanum oil. Carvacrol 75 ÷ 80%; linalool 5 ÷ 10%; thymol
5 ÷ 10%; D-limonene 0 ÷ 5%
Rosemary oil. Beta pinene 10 ÷ 15%; camphor 10 ÷ 15%; camphene
5 ÷ 10%. D-Limonene 0 ÷ 5%; terpineol 0 ÷ 5%; linalool 0 ÷ 5%.
The formulations were suitably diluted for the bioassays described
hereafter.
Repellent films were prepared by Artibal (Sabiñánigo, Spain) from
corona-treated polypropylene (30 μm thickness), following a patented
procedure (European Patent EP1657181). The coating included 4%
(w/w) of the above-mentioned essential oils. Each film was analysed
for the volatile composition and tested for the repellent effectiveness
in the bioassays described in the following after one-month storage in
aluminium-polyethylene hermetically sealed bags.