The aims of this research were to determine the chemical composition of the essential oil of three Tunisian plants and to
evaluate their biological activity against eggs, larvae, and adult insects of
Ectomyelois ceratoniae Zeller. The essential
oils extracted from leaves of
Thymus capitatus
(L.) Hoffmanns. & Link,
Rosmarinus officinalis
L. and needles of
Pinus
halepensis
Mill. were analyzed by gas chromatography-mass spectrometry; 34, 16, and 56 constituents were identified,
respectively. The major constituents were (Z)-caryophyllene (23.8%), β-myrcene (20.5%) and α-pinene (13.3%) in
P.
halepensis oil, carvacrol (66.9%),
p-cymene (9.1%), and δ-terpinene (6.2%) in
T. capitatus oil and 1,8-cineole (47.5%),
camphor (14.9%), α-pinene (14.1%), and borneol (13.1%) in
R. officinalis oil. The insecticidal effects of essential oils on
eggs, larvae, and adults of
E. ceratoniae were investigated. Ovicidal activity of oils was studied by spray on eggs while
larvicidal and adulticidal activities were assessed by fumigation and spray. Number of hatched eggs was verified after 10
d, larva and adult mortalities were observed after 6, 12, and 24 h. Globally, eggs and larvae were the most resistant to the
three different oils, needing higher doses to obtain a higher mortality. The spray method was most effective than fumigation.
Essential oil extracted from
T. capitatus proved to be very toxic towards
E. ceratoniae on all three phases at the dose of 20
μL mL
-1 (100% inhibition), followed by the oil from
R. officinalis (90-100% inhibition), nevertheless, weak activity was
obtained with
P. halepensis oil (68.3-85% inhibition). Results obtained may suggest that the essential oils of
T. capitatus
and
R. officinalis possess high insecticidal activity and therefore, can be used in biotechnological application as natural
preservative in stored dates and could be useful in managing populations of
E. ceratoniae in field.
