Diversity of aggressive Aedinian fauna and susceptibility of Aedes albopictus (Skuse, 1894) to <i>Ageratum conyzoides</i> L., 1753 and <i>Chromolaena odorata</i> L. Robinson, 1970 (Asteraceae) essential oils in some towns from southern Cameroon

Abstract

Background: A good knowledge of Aedes diversity and their biting cycle is necessary for better planning of vector control interventions against arboviruses diseases. This study aims to determine the diversity of Aedes and the biting cycle of Aedes albopictus in urban and suburban areas of Douala, Kribi, and Ayos to propose a method for vector control based on Ageratum conyzoides L., 1753 and Chromolaena odorata L., 1970 (Asteraceae) essential oil.

Methods: Larvae were sampled by dipping method and reared by Desfontaine method. The aggressiveness of Aedes was determined by the outdoors Human Landing Catches method from 6 am to 6 pm. Captured mosquitoes were morphologically identified using identification keys. Essential oils from fresh leaves of A. conyzoides and C. odorata were extracted by hydrodistillation using Clevenger while the chemical composition was determined by GC-MS. Insecticide tests were carried out according to WHO protocol on matures Ae. albopictus larvae.

Results: Ae. albopictus (n=3499; 80.5%) was the most abundant species in urban and suburban areas followed by Ae. unilineatus (n=392; 9.02%) and Ae. aegypti (n=210; 4.83%). The mean biting rate of Aedes was 21.52 bites/person/day (b/p/d). In urban and suburban areas Ae. albopictus (18.22 b/p/d) was the most aggressive species followed by Ae. unilineatus (2.04 b/p/d) and Ae. aegypti (1.09 b/p/d). Precocene I (54.4%) and Androencecalinol (24.69%) were the major compounds of A. conyzoides fresh leaves essential oil. Geijerene (20.02%) and trans-Muurola-4(14), 5-diene (19.15%) were the major compounds of C. odorata fresh leaves essential oil. A. conyzoides fresh leaves essential oil was the most effective with 100% mortality after 10 hours of exposure at 75 ppm concentration.

Conclusion: This study reveals that Aedes was more aggressive in urban areas than in suburban areas. Aedes albopictus was the most aggressive species. A. conyzoides fresh leaves essential oil should be considered in the implementation of control strategies against Aedes.