Use Of Pyhtociiemical Extracts From Citrus Fruit Species In Sustainable Control Of Vectors Of Malaria In Selected Rural Communities In Cross River State, Nigeria:- Effiom, Okoi E

ABSTRACT

Mosquitocidal activity of phytochemical extracts from citrus fruits was investigated in three rural malaria endemic, Mbube, Ekori and Abini communities, in Cross River State, Nigeria. The survey involved collection and identification of adult mosquitoes from human living rooms, and larvae from several breeding sites. The mosquito vectors identified were mostly Anopheles gambiae complex (sensu stricto, s.s.) (437 adults and 152 larvae) and Anophelesfunestus (213 adults and 47 larvae). A total of 705 mosquito larvae were collected and out of which Culex 262 (37.2%) were significantly more than those of Anopheline 200 (28.4%) and Aedes 243 (34.4%), and in these cases, Abini (Biase) community had more larvae 260 (36.9%). Of the total of 650 adult mosquitoes caught, females 574 (88.3%) were significantly more than males 76 (1.7%). Dissections of mosquitoes revealed that 212 (70.7%) were infected with malaria parasites with catches from Ekori having the highest rate of infection. The degree of efficacies of extracts on adults and larvae of mosquitoes were determined and matched with controls, and the result showed that pulp extracts of C. reticulata proved more potent against larvae within 1 •minute of application than those of C. sinensis, C. aurantifolia, C. limonum and C. vitis. Extracts from peels of C. sinensis, C. reticulata, C. limonum and C. aurantifolia and the pulp extract of C. sinensis were very potent against the adults. However, extracts from seeds of C. sinensis and pulp of C. limonum and C. aurantifolia did not show any lethal effect at both low and high concentrations. Topical application by human volunteers-revealed repellent effect at a concentration of 25% for more than 5 hours. Alkaloids, flavonoids, saponins, phenolics and tannins were identified as the active compounds of the extracts. The result of verification of relationship using Pearson Correlation Coefficient test revealed significant relationship (P<0.001) between alkaloids of C. reticulata, C. limonum, C. aurantifolia and C. vitis and their respective potency and kill time (KT) and also flavonoids of some extracts. Verification of the correlation coefficient between pH and the potency of the various extracts' showed that only pH values of C. limonum extracts (0.999) correlated significantly (P > 0.01). The results of the study revealed that the extracts are effective in killing mosquitoes both in the laboratory and in field situations and therefore can be adopted for sustainable destruction of mosquitoes.