Combined Effect of Methanol Extracts and Essential Oils ofCallistemon rigidus(Myrtaceae) andEucalyptus camaldulensis(Myrtaceae) againstAnopheles gambiaeGiles larvae (Diptera: Culicidae)

Abstract

Biopesticides from botanicals are nowadays actively encouraged in the mosquito control program because of their low mammalian toxicity, biodegradability, and target specificity. However, leaf methanolic extracts and essential oils of Callistemon rigidus and Eucalyptus camaldulensis were evaluated individually and in combination on third- and fourth-instar larvae of Anopheles gambiae. The extracts were tested individually and in combination at doses of 125, 250, 500, and 1000 ppm while essential oils were applied at 25, 50, 100, and 200 according to the standard protocol of WHO. The commercial insecticide Bi-one tested at the recommended dose of 1000 ppm was used as positive control while the solution of tap water containing 0.5 ml of methanol was used as negative control. The mortality of the larvae was recorded after 24 h postexposure. In the results, 100% mortality of the larvae was recorded with the extracts of C. rigidus and the combinations E50% : C50% and E25% : C75% of the plants as well as positive control (1000 ppm). Similarly, essential oils of the two plants and their combinations caused 100% mortality of the larvae. Among the various combinations of the extracts and essential oils, only the combination E75% : C25% of essential oils presented a synergistic effect. Therefore, the essential oil combination (E75% : C25%) of the plants E. camaldulensis and C. rigidus is recommended in order to promote the its use in the form of natural biocide in the implementation of effective insect controls against the mosquito larvae, vector of malaria.

Adulticidal Activity of Hyptis suaveolens, Chenopodium ambrosioides and Lippia adoensis Leaf Extracts and Essential Oils against Anopheles gambiae (Diptera: Culicidae)

“…A synergistic action of methanolic extract and essential oils of Callistemon rigidus combined with Eucalyptus camaldulensis against An. gambiae larvae was reported by Younoussa et al [9].…”

Adulticidal Activities and Synergistic Effects of Citrus Aurantiifolia Peels and Hyptis spicigera Leaves Essential Oils against Anopheles gambiae s.l. (Diptera: Culicidae)

“…The management of insecticide resistance remains a major challenge for achieving effective malaria elimination. In insect pest control agent research, the insecticide combination approach is encouraged not only to optimize the efficacy of insecticide products but also to solve the problem of insect resistance, as this approach might apparently preserve the efficacy of the insecticide product for many years 17 . The main goal of this study was to evaluate the insecticidal effects of EOs from C. aurantiifolia, H. spicigera and their combinations on female adults of An.…”

“…The LC50 values of the EOs of all the plants were subsequently determined, as were those of the different binary combinations tested, which allowed us to identify the various interactions between combinations, as described by Lame et al 17 : Interactions between combinations were determined using the cotoxicity index and the synergistic factor.…”

Mediterranean Plants as Potential Source of Biopesticides: An Overview of Current Research and Future Trends

“…The larvae were placed in 250 mL of solution containing 249 mL of distilled water and 1 mL of essential oils or a mixture (six different dosages were tested for each compound), and their mortality was recorded after 24 h of exposure to the treatment [ 81 ]. Similar approaches were used in other studies featuring larvae of other mosquito species, such as Culex pipiens , Culex restuans , Aedes aegypti , Aedes albopictus, and Anopheles gambiae [ 77 , 82 , 88 , 160 , 161 ]. Musso and colleagues used immersion techniques to study the larvae of the nematode Panagrolaimus rigidus [ 109 ].…”