Evaluation of Icacina senegalensis and Jatropha curcas Extracts for the management of sweet potato beetle Cylas spp. (Coleoptera: Brentidae)
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Date
2012-05-18
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Abstract
The adverse environmental effect of synthetic pesticides such as environmental pollution, destruction of beneficial insects, disruption of the ecosystem and contamination of harvested produces, have necessitated the call for environmentally safer, easily degradable and target specific insecticides. An experiment was therefore, conducted at the College of Agriculture Education, University of Education, Winneba, Mampong Ashanti Campus to determine the efficacy of different parts of Icacina senegalensis and Jatropha curcas leaf extracts for the management of sweet potato beetle (Cylas spp.). The treatments which were arranged in a Randomized Complete Block with three replications consisted of one time application of the following: 0.3 kg/ha fresh tuber extracts of I. senegalensis (T1), 0.3 kg/ha dried tuber extracts of I. senegalensis (T2) and 0.3 kg/ha of fresh leaves extracts of I. senegaleensis (T3) (0.18 g /1.5 L of water each per 6 m2 plot). The others were two times application of 0.15 kg/ha of fresh tuber of I. senegalensis (T4), 0.15 kg/ha of dried tuber extracts of I. senegalensis (T5), 0.15 kg/ha of fresh leaves extracts of I. senegalensis ( T6 ), (0.09 g/750 ml of water each per 6 m2 plot). And one time application of (0.3 kg/ha each of fresh and dried leaves extracts of J. curcas respectively represented T7 and T8 (0.18 g/1.5 L water each per 6 m2 plot). 30 ml of Dursban (chlorpyrifos) in 15 L of water represented T9 and T10 the control (no pesticide). The fresh leaf and tuber extracts of I. senegalensis (0.15 kg/ha and 0.3 kg/ha) and the chlorpyrifos treated plots had significantly fewer beetles at the base of the crop. The fresh leaf and tuber extracts of I. senegalensis (0.15 kg/ha and 0.3 kg/ha) and chlorpyrifos treatments also suppressed beetle infestation of the tubers, reduced tuber damage and increased marketable tubers. Extracts of the fresh plant parts were more effective than extracts from the dried parts where damaged almost doubled and yield halved. Beetle population correlated positively with vine damage, tuber damage significantly (p<0.05) and negatively with marketable yield. It is therefore, recommended that sweet potato growers in the transitional ecological zone of Ghana can minimize tuber damage by Cylas spp. through application of fresh plant extracts of I. senegalensis during land preparation and one month after planting on the planting ridges.
Description
A Thesis from the Department Of Crop and Soil Science submitted to the School of Graduate Studies of the Kwame Nkrumah University of Science and Technology, in partial fulfilment of the requirements for the award of Master of Science (M.Sc.) Degree in Crop Protection (Entomology).