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TAXONOMIC STUDIES of Lippia Javanica (BURM F.) SPRENG. (VERBENACEAE) COMPLEX in EAST AFRICA USING MORPHOLOGICAL and MOLECULAR CHARACTERS and EVALUATION of Its PESTICIDAL EFFICACY in APHIDS

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dc.contributor.author MASINDE, Collins Wafula
dc.date.accessioned 2019-11-18T08:47:14Z
dc.date.available 2019-11-18T08:47:14Z
dc.date.issued 2018
dc.identifier.uri https://repository.maseno.ac.ke/handle/123456789/1350
dc.description.abstract Lippia javanica (Burm. F.) Spreng occurs naturally in eastern, central and southern Africa. It has widely been used as herbal tea, for ethnomedicinal applications and as a botanical pesticide. Lippia javanica species exhibit great morphological and chemical variations which are notable across a number of natural populations. Differences in morphological taxonomy on important characters such as peduncle length and number of inflorescence per axil have been reported which has led to the recognition and identification of infraspecific taxa of var. whytei auct and var. javanica in Southern Africa region, creating a major taxonomic conflict in Lippia javanica, a scenario which needs to be resolved. Many plant extracts show a broad spectrum of activity against pests and such products have long been touted as attractive alternatives to synthetic chemical pesticides for pest management because they pose little threat to the environment. There is a general paucity of information on taxonomic studies of L. javanica on the morphological, molecular and chemical properties, which can aid in the comprehensive understanding of the taxonomy and classification of L. javanica in East Africa region. Chemotaxonomic studies have shown strong chemical variations in phytochemical compounds of L. javanica in other African regions with little information available in Kenya. There is hardly any information on the efficacy of the extracts of L. javanica on common aphids of cowpeas in Kenya. The purpose of this study was to undertake taxonomic studies on the proposed variants var. javanica and var. whytei. of L. javanica complex based on morphometrics, molecular and phytochemical characters, and evaluate its efficacy as a botanical pesticide for control of aphids (Aphis craccivora) (C.L) Koch of cowpeas (Vigna unguiculata). Data on morphological characters were obtained from the national Museums of Kenya herbarium preserved specimens. Observations were also made from specimens collected from Maralal, Naivasha, Nyahururu (Rumuruti) Sotik, Sondu, Kedong, Kapsowar, Ngong and Narok sites of Kenya to integrate this information with the morphological data from the herbarium preserved specimens. Molecular studies involved the use of Inter-simple sequence repeats and Random Amplified Polymorphic Deoxyribonucleic acid to determine genetic variation of freshly collected young leaf tissues. The collected field specimens were screened to establish their phytochemical composition. A completely randomized block design with five treatments (1%, 5%, 10%, positive, and negative controls) was used to evaluate the efficacy of L. javanica extracts against the aphids in the field. Cluster analysis and principal component analysis of morphological data revealed that L. javanica had no significant variations. Similar band pattern were also portrayed by all the analyzed specimens using Inter Simple Sequence Repeats and Random Amplified Polymorphic Deoxyribonucleic acid markers. The morphological and molecular study revealed that L. javanica is one species. The species was found to be rich in a variety of phytochemical compounds such as phenols, flavonoids, tannins, alkaloids, and terpenoids that perhaps exhibited pesticidal effects on the aphids. Phenolic glycosides, resins and polynuroids were absent. Application of the various concentrations of L. javanica extracts significantly suppressed the abundance of aphids on cowpeas at P≤ 0.05. The mixture of L. javanica extracts at 10% was more effective than 1% and 5% extracts concentration. The 10% extract was not significantly different from the synthetic pesticide hence can be a suitable botanical pesticide for controlling Aphis craccivora of cowpeas. The findings from this study would greatly assist taxonomists and plant systematists in correctly classifying and identifying the highly variable Lippia javanica, and will be useful to farmers in the control of common aphids of cowpeas. en_US
dc.publisher Maseno University en_US
dc.title TAXONOMIC STUDIES of Lippia Javanica (BURM F.) SPRENG. (VERBENACEAE) COMPLEX in EAST AFRICA USING MORPHOLOGICAL and MOLECULAR CHARACTERS and EVALUATION of Its PESTICIDAL EFFICACY in APHIDS en_US
dc.type Thesis en_US


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