The German, Blattella germanica and the American, Periplaneta americana cockroaches are on the top of serious pests that threaten human health, hygiene, and food safety. The hazard effects of the conventional insecticides directed the focus to safe bio-alternatives. So, this study aimed to evaluate the contact, repellent, and fumigant activities of four essential oils (EOs) namely, cardamom (Elettaria cardamomum), jasmine (Jasminum grandiflorum), lemon (Citrus limon), and anise (Pimpinella anisum) against B. germanica and P. americana adults. The contact toxicity was determined at five EO concentrations of 5, 10, 20, 30, and 40 µl/ml and at three-time intervals, then LC50 and LC90 were estimated. The repellent percentages of the tested EOs were recorded at 1, 6, 12, and 24-h post exposure and the fumigant toxicity was recorded at 48-h post exposure. Also, Gas- chromatography mass spectrophotometry (GC-MS) analysis of the tested EOs was practiced. Results revealed that the four tested EOs had significant contact, repellent, and fumigant activities (P ˂ 0.001) against both B. germanica and P. americana adults. Concerning the contact and repellent activities, E. cardamomum was the most effective EO against both cockroaches. It exhibited the lowest LC50 value of 6.373 µl/ml and LC90 value of 36.443 µl/ml against B. germanica; and 27.485 µl/ml and 219.235 µl/ml, respectively against P. americana. Also, E. cardamomum EO induced the highest repellency percentages of 74.00% ± 8.12, 66.00% ± 4.00, 50.00% ± 3.16, and 44.00% ± 5.10 at 1, 6, 12, and 24-h post exposure, respectively against B. germanica. Against P. americana, it induced 56.00% ± 2.45, 50.00% ± 2.45, 46.00% ± 4.00, and 28.00% ± 2.00 repellency percentages at 1, 6, 12, and 24-h post exposure, respectively. Regarding the fumigant toxicity, it was shown that C. limon was the most effective EO. It caused 48.00% ± 5.6 mortality to B. germanica and 36.00% ±3.00 to P. americana. GC-MS analysis revealed that the major constituents of E. cardamomum EO were α-pinene (12.53%), trans-β-terpinyl butanoate (9.44%), α-terpineol (9.39%) and isopulegol (5.72%). C. limon EO had three main components: d-limonene (57.95%), α-phellandrene (13.42%), and α-pinene (11.01%). In J. grandiflorum EO, the major constituents were p-cresol (26.11%), bergenin (23.27%) and 3-methoxytyramine (16.71%). In conclusion, the tested EOs, especially E. cardamomum and C. limon proved to have contact, repellent, and fumigant activities against B. germanica and P. americana and thus can be recommended to be used as safe, effective, and eco-friendly botanicals against cockroach infestations in sensitive situations where conventional insecticides would be improper.
Key words: Blattella germanica, Periplaneta americana, essential oils, fumigant, repellent, Elettaria cardamomum, Jasminum grandiflorum, Citrus limon, Pimpinella anisum.
|
