Contrasting efects of the alkaloid ricinine on the capacity of Anopheles gambiae and Anopheles coluzzii to transmit Plasmodium falciparum

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Parasites Vectors
Background: Besides feeding on blood, females of the malaria vector Anopheles gambiae sensu lato readily feed on natural sources of plant sugars. The impact of toxic secondary phytochemicals contained in plant-derived sugars on mosquito physiology and the development of Plasmodium parasites remains elusive. The focus of this study was to explore the infuence of the alkaloid ricinine, found in the nectar of the castor bean Ricinus communis, on the ability of mosquitoes to transmit Plasmodium falciparum. Methods: Females of Anopheles gambiae and its sibling species Anopheles coluzzii were exposed to ricinine through sugar feeding assays to assess the efect of this phytochemical on mosquito survival, level of P. falciparum infection and growth rate of the parasite. Results: Ricinine induced a signifcant reduction in the longevity of both Anopheles species. Ricinine caused acceleration in the parasite growth rate with an earlier invasion of the salivary glands in both species. At a concentration of 0.04 g l −1 in An. coluzzii, ricinine had no efect on mosquito infection, while 0.08 g l −1 ricinine-5% glucose solution induced a 14% increase in An. gambiae infection rate. Conclusions: Overall, our fndings reveal that consumption of certain nectar phytochemicals can have unexpected and contrasting efects on key phenotypic traits that govern the intensity of malaria transmission. Further studies will be required before concluding on the putative role of ricinine as a novel control agent, including the development of ricinine-based toxic and transmission-blocking sugar baits. Testing other secondary phytochemicals in plant nectar will provide a broader understanding of the impact which plants can have on the transmission of vector-borne diseases.
Plasmodium falciparum, Anopheles gambiae, Ricinine, Malaria transmission, Benjamin K. Koama, Edwige Guissou, ACE: Mycotoxin and Food Safety, ACEMFS, Federal University of Technology, Minna