Evaluation of Orange Peel Citrus Sinensis (L) As a Source of Repellent, Toxicant and Protectant against Zabrotes Subfasciatus (Coleoptera: Bruchidae)

Continued application of synthetic insecticides arise development of resistance and pollution of the environment. Laboratory experiments were conducted to test the efficacy of products of orange (Citrus sinensis) peels in the control of the stored products beetle Zabrotes subfasciatus (L) in stored haricot beans (latin name). Different levels of the extracts and essential oil of Citrus sinensis was tested. Conventional synthetic insecticide, Pirimiphos-methyl, was used as a standard check. Toxicity potential of different extracts of C. sinensis was tested against Z. subfasciatus. Extracts prepared using different solvents against the beetles were not toxic. However, essential oils at highest rate of 750mg applied at 3ml per filter paper gave 100 % mortality after 24 h. Beans treated with 15g of sun dried powder of orange peel and 750mg of essential oil killed 65% and 67% of Z. subfaciatus after 96 hours respectively. Powders from ground peels caused significant reduction in progeny emergence of Z. subfasciatus (P< 0.05). There was no progeny produced when essential oil was used, even at lower dosage levels of 30mg. All the treatments were repellent to Z. subfasciatus. The essential oil of orange peel had a high level of toxicity in the fumigation bioassay against Z. subfasiatus. Key words: Citrus sinensis, essential oil, Zabrotes subfasciatus, Pirimiphos-methyl, Percent weight loss, Damage assessment

Ethnobotanical study of some of mosquito repellent plants in north-eastern Tanzania

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. 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. 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. 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

Extractives of Millettia ferruginea, Tephrosia vogellii and tephrosia pentaphylla against the bean bruchid, Zabrotes subfaciatus Ethiopain head cabbage field

No Abstract. SINET Vol. 30 (1) 2007: pp. 49-5

Prevalence of termites and level of damage on major field crops and rangelands in the Manasibu District, western Ethiopia

ABSTRACT: The current status of termite damage on maize (Zea mays(L.)), teff (Eragrostis tef (Zuccagni) Trotter), sorghum (Sorghum bicolor(L.)) and rangelands was studied in five Kebele administrations (study sites) and on three farmers' fields in every Kebele, in Manasibu District, Wellega Zone of Oromiya Regional State. Termite samples were collected from infested crop fields and rangelands, identified to the genus level with keys to the Ethiopian termites, and percentage occurrence for each genus was determined. Six genera of termites: Ancistrotermes, Macrotermes,Microtermes, Odontotermes, Pseudacanthotermes and Trinervitermes wereidentified. The first five genera belong to the subfamily Macrotermitinaewhereas Trinervitermes belongs to Nasutitermitinae. All of the generabelonged to the family Termitidae. Subterranean termites in general andMicrotermes in particular, were found to be the most prevalent termites in the study area. The damage that termites caused to maize and sorghum were assessed by the use of quadrates and that of teff by laying wooden frames in the quadrates. For all the three crops, damage was assessed at vegetative, flowering, and maturity stages. It was found out that the levels at which the three crops were damaged by termites were significantly different from each other. Teff was the most seriously damaged crop in the study area, followed by maize, while sorghum was the least affected crop. Damage at different stages, within each crop, were also found to be significantly variable from each other. To evaluate the impact of termites on rangelands in the absence and presence of grazing by livestock, three plots of rangelands were fenced and protected for six months. It was found that the protected plot of the rangelands significantly had higher percent vegetation cover and lower number of termite foraging holes per m2. From the study, it can be concluded that the genus Microtermes was the major termite species attacking crops and rangelands in Manasibu district, implying that most control strategies should focus on this genus, especially to control termites on teff and maize

Law Against Reality? Contextualizing The Ethiopian-Eritrean Border Problem

ASC – Publicaties niet-programma gebonde