ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Insect repellent and insecticidal potential of two Eucalyptus species essential oils from subtropical desert climate

Rafia Rehman, Waqas Ahmad, Rabeea Muzaffar, Afsar Bano, Iqra Sajid, Abad Ullah Ahsan, Liaqat Ali, Muzammal Hussain, Zarif Gul, Usama Naeem, and Ghulam Mustafa

Department of Biological Sciences, National University of Medical Sciences, Rawalpindi, Pakistan

E-mail: rafia.rehman@numspak.edu.pk

Received: 20 June 2023  Accepted: 12 November 2023

Abstract:

In the present study, in order to search greener solution for food insects, the insecticidal and insect repellent potentials of e. oils of E. camaldulensis and E. citriodora leaves (different concentrations) have been evaluated against two stored food insects, i.e., rice weevil (Sitophilus oryzae) and red flour beetle (Tribolium castaneum). Insecticidal activity of these e. oils against Sitophilus oryzae (rice weevil) showed 76.67% mortality for E. citriodora and 40% for E. camaldulensis e. oil (100 µL/mL in each case), after 96 contact hours. For Tribolium castaneum (red flour beetle), 66.67% mortality rate of E. camaldulensis e. oil was achieved by100 µL/mL essential oil after 96 contact hours while 76.67% for E. citriodora e. oil at same concentration. The % repellent activity of both e. oils showed that it decreased with exposure time but increased with concentrations of essential oil. Hence the repellent activity of 100 µL/mL concentration of E. camaldulensis e. oil against Sitophilus oryzae (rice weevil) was 90% after 24 h which decreased up to 76.67% after 96 h of exposure time. In case of E. citriodora e. oil, % repellency against same insect was found to be 73.33% for 100 µL/mL concentration which decreased up to 56.67% after same time interval. In case of Tribolium castaneum (red flour beetle), the repellent activity of 100 µL/mL E. camaldulensis e. oil was 86.67% after 24 h and decreased to 73.33% after 96 h’ exposure. The 100 µL/mL E. citriodora e. oil was having repellent activity 76.67% after 24 h which decreased to 60% after 96 h. Differences in insecticidal and insect repellent activities of two essential oils were found to be associated with major chemical components as indicated by GC–MS analysis. This study suggests that combination of these two e. oils can be very effective to repel as well as kill the food born insects. Also, these e. oils can be proved excellent green alternative of environmental damaging synthetic pesticides.

Graphical abstract

Keywords: Eucalyptus citriodora; Eucalyptus camaldulensis; Essential oils; Insecticidal activity; Repellent activity; Sitophilus oryzae; Tribolium castaneum

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-03244-x

Chemical Papers 78 (4) 2369–2384 (2024)