Abstract
The rice weevil,
Sitophilus oryzae
(L.), and the red flour beetle,
Tribolium castaneum
(Herbst), are key stored-product pests in Egypt and worldwide. The extensive use of synthetic insecticides has led to adverse effects on the environment, human health, and pest resistance. As a result, environmentally friendly pest management alternatives are desperately required. The botanical oils of jojoba,
Simmondsia chinensis
(L.)
,
and rosemary,
Rosmarinus officinalis
L. plants growing in Egypt were extracted, identified by gas chromatography/mass spectrometry (GC–MS), and evaluated for their insecticidal activity against
S. oryzae
and
T. castaneum
. The main constituents identified in BOs were carvyl acetate (20.73%) and retinol (16.75%) for
S. chinensis
and camphor (15.57%), coumarin (15.19%), verbenone (14.82%), and 1,8-cineole (6.76%) for
R. officinalis.
The
S. chinensis
and
R. officinalis
BOs caused significant contact toxicities against
S. oryzae
and
T. castaneum
adults, providing LC
50
values of 24.37, 68.47, and 11.58, 141.8 ppm at 3 days after treatment (DAT), respectively.
S. chinensis
oil exhibited significant fumigation toxicity against both insects; however, it was more effective against
S. oryzae
(LC
50
= 29.52 ppm/L air) than against
T. castaneum
(LC
50
= 113.47 ppm/L air) at 3 DAT. Although the essential oil (EO) of
R. officinalis
significantly showed fumigation toxicity for
S. oryzae
(LC
50
= 256.1 and 0.028 ppm/L air at 1 and 3 DAT, respectively)
,
it was not effective against
T. castaneum
. These BOs could be beneficial for establishing IPM programs for suppressing
S. oryzae
and
T. castaneum
.