Fumigant Toxicity of Essential Oils From Chemotypes of Curry Tree ( Murraya koenigii ) Against Adult African Malaria Mosquito ( Anopheles gambiae sensu stricto )

The toxicity of fumigant formulations of essential oils (EOs) from curry tree ( Murraya koenigii (L.) Spreng (Rutaceae)) against African malaria adult mosquito ( Anopheles gambiae sensu stricto (Giles, 1902) (Diptera: Culicidae: Culicini)) was evaluated to identify most effective chemotype of the curry tree against the mosquitoes. Ninety‐two compounds (91.78%–96.47% coverage) in the EO profiles were identified, among which EO isolated from curry tree chemotype from Kibwezi was most toxic. This chemotype had a median lethal dose (LD 50 ) of 3.6 × 10 −3 mg/cm 3 (95% CI: 2.70–4.58) and a lethal time (Ti 50 ) of 1.91 ± 0.086 h ( p < 0.001). The equivalent LD 50 of EOs of chemotypes from Mombasa, Makindu, and Malindi in Kenya was 4.9 × 10 −3 , 6.6 × 10 −3 , and 8.5 × 10 −3 mg/cm 3 , respectively. The Kibwezi EO chemotype was rich in sesquiterpenes, notably β‐elemene 32, trans‐caryophyllene 35, α‐humulene 39, and globulol 57, whereas Malindi EO chemotypes were enriched in oxygenated sesquiterpenes, particularly caryophyllene oxide. The EOs formed three clusters: Kibwezi/Mombasa, enriched in caryophyllene C1, Malindi, enriched in caryophyllene oxide C2, and Makindu, enriched in β‐selinene C3. Our findings indicate that chemotypes in curry tree potentially and significantly influence EO composition and bioactivity, with EO from chemotype from Kibwezi exhibiting most toxic fumigant potential. This chemotype is thus a potential eco‐friendly alternative for control of African malaria adult mosquito.