Insecticidal potential of essential oils from Cupressus lusitanica growing in ecological zones of Rwanda against adult housefly, Musca domestica L

Abstract

The housefly, Musca domestica Linnaeus is a household pest mostly controlled by use of synthetic insecticides that often affect the environment and promote insecticide resistance. Plants of Cupressaceae family are often used locally in Rwanda and Uganda as an eco-friendly way to repel houseflies. In spite of this high utility of the plant, scientific proof of its efficacy is still limited. This study aimed at assessing the insecticidal activity of essential oils (EOs) from Cupressus lusitanica Mill. (Cupressaceae) growing in three agro-ecological zones (AEZs) of Rwanda; highland (Burera), midland (Huye) and lowland (Kayonza) against adult houseflies. EOs were extracted from fresh leaves using steam distillation method. Male and female adult houseflies were exposed to individual test solutions of 90, 70, 50 and 30% v/v (DDVP or EOs/Acetone) for 6, 12 or 24 h. The levels of repellant activity, contact and fumigant toxicity were then recorded. Acetone and DDVP insecticide served as negative and positive test controls, respectively. DDVP showed higher toxicity and repellant activity compared to tested EOs, whereas Acetone repelled less than 14% of exposed houseflies in 24 h. The EOs from leaves collected in lowlands had higher fumigant and contact toxicity, followed by that from midlands, while least toxic effects were observed for EOs from highlands. The higher repellant activity was exhibited by EOs from midlands, followed by oil from lowlands. The observed promising activity among investigated AEZs implies that the EOs of C. lusitanica could be used as alternative to synthetic insecticides for control of the housefly