Insecticidal activity of two formulations of essential oils against the cereal leaf beetle

Figures & data

Table 1. Essential oils percentage composition, as identified by GC–MS and quantified by GC-FID.

RI^a	Compound	Cymbopogon citratus	Pelargonium graveolens	Rosmarinus officinalis	Thymus vulgaris
926	Tricyclene	0.16	–	–	–
931	α-Thujene	–	–	0.37	0.35
939	α-Pinene^b	0.35	0.66	10.27	1.27
953	Camphene	0.74	–	4.53	1.51
978	1-Octen-3-ol	–	–	–	0.88
980	β-Pinene^b	–	–	7.03	–
987	6-methyl-5-Hepten-2-one	1.49	–	–	–
991	Myrcene^b	–	–	0.92	1.34
1011	3-Carene^b	–	–	0.29	–
1018	α-Terpinene^b	–	–	–	1.09
1026	p-Cymene^b	–	–	2.81	16.40
1031	Limonene^b	3.87	–	–	0.33
1033	Eucalyptol^b	–	–	43.35	1.29
1040	cis-β-Ocimene	0.55	–	–	–
1050	trans-β-Ocimene	0.40	–	–	–
1062	γ-Terpinene^b	–	–	–	5.74
1098	Linalool^b	0.72	5.22	0.77	4.68
1111	cis-Rose oxide^b	–	1.57	–	–
1127	trans-Rose oxide^b	–	0.60	–	–
1143	Camphor^b	–	–	14.01	1.87
1151	Menthone^b	–	2.35	–	–
1153	β-Citronellal^b	0.85	–	–	–
1164	Isomenthone	–	6.34	–	–
1165	Borneol^b	1.13	–	4.88	1.76
1177	Terpinen-4-ol	–	–	0.94	1.78
1177	Verbenol^t	0.89	–	–	–
1189	α-Terpineol	0.30	–	2.20	0.23
1204	Decanal	0.37	–	–	–
1228	Citronellol^b	–	32.56	–
1235	Thymol methyl ether	–	–	–	0.58
1240	Neral	29.59	–	–	–
1244	Carvacrol methyl ether	–	–	–	0.92
1255	Geraniol^b	3.94	14.92	–	–
1270	Geranial^b	39.68	0.78	–	–
1279	Citronellyl formate	–	8.86	–	–
1285	Bornyl acetate^b	0.33	–	1.94
1290	Thymol^b	–	–	–	48.07
1298	Carvacrol^b	–	–	–	2.75
1300	Geranyl formate	–	3.59	–	–
1356	Eugenol^b	0.31	–	–	0.23
1376	α-Copaene	0.24	0.79	0.29	–
1384	β-Bourbonene	–	2.26	–	–
1385	Geranyl acetate^b	5.41	–	–	–
1391	β-Elemene	0.27	–	–	–
1404	Methyleugenol	0.30	–	–	–
1418	β-Caryophyllene^b	2.88	1.81	3.85	5.91
1444	Citronellyl propionate^b	–	0.58	–	–
1447	trans-Isoeugenol	0.34	–	–	–
1454	α-Caryophyllene^b	0.31	–	0.47	–
1475	Geranyl propionate	–	1.06	–	–
1480	Germacrene D	–	1.47	–	–
1524	δ-Cadinene	0.46	2.18	–	0.26
1529	Citronellyl butyrate	–	0.64	–	–
1549	Elemol	0.30	–	–	–
1564	Geraniol butyrate	–	1.36	–	–
1581	Caryophyllene oxide^b	0.85	–	1.07	0.33
1584	Phenethyl tiglate	–	1.24	–	–
1630	γ-Eudesmol	–	6.87	–	–
1700	Geranyl tiglate	–	1.65	–	–
	Total identified compounds	97.06	99.37	100.00	99.59

^aRI: identification based on Kovat's retention indices (HP-5MS capillary column) and mass spectra.

^bIdentification confirmed by co-injection of authentic standard.

^tTentative identification.

Table 2. Mortality of Oulema melanopus adults after tarsal experiment with the essential oils from Rosmarinus officinalis with Cymbopogon citratus.

	Mortality (after 24 h) (%)
Applied concentration (%)	Essential oil	Encapsulation
0.12	0	0
0.204	8	14
0.36	30	32
0.58	46	66
1	90	86
Untreated control	0.1

Table 3. Mortality of Oulema melanopus larvae after tarsal experiment in five concentrations with the essential oils from Pelargonium graveolens with Thymus vulgaris.

	Mortality (after 24 h) (%)
Applied concentration (%)	Essential oil	Encapsulation
0.12	50	70
0.204	90	80
0.36	100	80
0.58	100	90
1	100	90
Untreated control	60

Table 4. Mortality of Oulema melanopus larvae after tarsal experiment in one low concentration with the essential oils from Pelargonium graveolens with Thymus vulgaris.

	Mortality (after 24 h) (%)
Applied concentration (%)	Essential oil	Encapsulation
0.12	48	46
Control (water)	28
Control (rapeseed oil and Tween 20)	52