Ethnobotanical study of some of mosquito repellent plants in north-eastern Tanzania.
BACKGROUND
The use of plant repellents against nuisance biting insects is common and its potential for malaria vector control requires evaluation in areas with different level of malaria endemicity. The essential oils of Ocimum suave and Ocimum kilimandscharicum were evaluated against malaria vectors in north-eastern Tanzania.


METHODS
An ethnobotanical study was conducted at Moshi in Kilimanjaro region north-eastern Tanzania, through interviews, to investigate the range of species of plants used as insect repellents. Also, bioassays were used to evaluate the protective potential of selected plants extracts against mosquitoes.


RESULTS
The plant species mostly used as repellent at night are: fresh or smoke of the leaves of O. suave and O. kilimandscharicum (Lamiaceae), Azadirachta indica (Meliaceae), Eucalyptus globules (Myrtaceae) and Lantana camara (Verbenaceae). The most popular repellents were O. kilimandscharicum (OK) and O. suave (OS) used by 67% out of 120 households interviewed. Bioassay of essential oils of the two Ocimum plants was compared with citronella and DEET to study the repellence and feeding inhibition of untreated and treated arms of volunteers. Using filter papers impregnated with Ocimum extracts, knockdown effects and mortality was investigated on malaria mosquito Anopheles arabiensis and Anopheles gambiae, including a nuisance mosquito, Culex quinquefasciatus. High biting protection (83% to 91%) and feeding inhibition (71.2% to 92.5%) was observed against three species of mosquitoes. Likewise the extracts of Ocimum plants induced KD90 of longer time in mosquitoes than citronella, a standard botanical repellent. Mortality induced by standard dosage of 30 mg/m2 on filter papers, scored after 24 hours was 47.3% for OK and 57% for OS, compared with 67.7% for citronella.


CONCLUSIONS
The use of whole plants and their products as insect repellents is common among village communities of north-eastern Tanzania and the results indicate that the use of O. suave and O. kilimandscharicum as a repellent would be beneficial in reducing vector biting. The widespread use of this approach has a potential to complement other control measures.
Kweka
Eliningaya J
EJ
Tropical Pesticides Research Institute, Division of Livestock and Human Disease Vectors Control, P,O, Box 3024, Arusha,Tanzania. Pat.kweka@gmail.com
Mosha
Franklin
F
Lowassa
Asanterabi
A
Mahande
Aneth M
AM
Kitau
Jovin
J
Matowo
Johnson
J
Mahande
Michael J
MJ
Massenga
Charles P
CP
Tenu
Filemoni
F
Feston
Emmanuel
E
Lyatuu
Ester E
EE
Mboya
Michael A
MA
Mndeme
Rajabu
R
Chuwa
Grace
G
Temu
Emmanuel A
EA
D000818:Animals; D000852:Anopheles / Q000187:drug effects*; D019448:Ethnobotany; D005260:Female; D006801:Humans; D007302:Insect Repellents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D019686:Lamiaceae / Q000737:chemistry; D008288:Malaria / Q000517:prevention & control; D008297:Male; D029582:Meliaceae / Q000737:chemistry; D009032:Mosquito Control / Q000379:methods*; D027822:Myrtaceae / Q000737:chemistry; D031339:Ocimum / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry; D013636:Tanzania; D029648:Verbenaceae / Q000737:chemistry
D007302:Insect Repellents; D010936:Plant Extracts; D010938:Plant Oils