Sachets sized 52.5 × 74.25 mm were prepared with repellent
films, with the coated side as the outer side of packages, and filled
with 25 g durum wheat semolina.
For the preference tests, one sachet made with the control film
and one made with the treated one were positioned at the sides of
rigid polyethylene white boxes (20 × 10 × 7 cm). Twenty adults of
the red flour beetle, unfeeded for 48 hours, were then released in
the centre of the boxes, and maintained in the dark until the end of
the trial, carried out at 25 °C and 70% RH. A control trial was also
performed, consisting of two semolina sachets made with control
film aimed at excluding other factors than the essential oil on the insect
behaviour. Each test was carried out in triplicate.
Boxes were checked after 2, 24 and 48 h, and the percentage of repellency
(R%) was calculated as aforementioned, with: