Etude photochimique et efficacité bio pesticide des extraits de tithonia diversifolia et de solanum aculeastrum contre les insectes ravageurs des plantes et des récoltes : cas de la chenille légionnaire, des pucerons noirs, des bruches de haricots et des charançons de maïs
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Date
2023-08
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UB, Faculté des Sciences
Abstract
Maize and bean crops are subject to several attacks by numerous pests in the field and in storage. Among these pests, fall armyworm and black aphids respectively reduce corn and bean yields in the field. The same applies to corn weevils and bean bruchids in stock. So, to find alternatives to the synthetic insecticides used against these pests, the pesticidal activity of extracts of Tithonia diversifolia (TD) and Solanum aculeastrum (SA), traditionally widely used as pesticides, were tested on these pests. Organic and aqueous extracts obtained by maceration were screened for their pesticidal effects against armyworms, black aphids, weevils and bruchids. The results showed that the aqueous extracts of TD leaves were more effective than those of SA on armyworm and black aphid. This efficacy can be seen in the high mortality of armyworms (88.9%) and black bean aphids (91.1%) at a dose of 250 g/L. The lethal dose 50 is 149.375 g/L of aqueous extracts of TD leaves against black aphids and 125.68 g/L of aqueous extracts of TD leaves against armyworm. In addition, hexane extracts of TD with a concentration of 4 mg/mL caused high mortality of 83.3% for corn weevils with a lethal dose 50 of 2.77 mg/mL and 100% mortality with a lethal dose 50 of 2.09 mg/mL against bean bruchids. In contrast, hexane extracts from SA leaves at a concentration of 4 mg/mL resulted in high mortality of 50% for maize weevils and 88.9% for bean leaf bruchids. Hexane extracts from the fruits of the same species caused high mortality of 61.1% for corn weevils and 100% for bean leaf bruchids. All these results clearly show that both species contain substances with pesticidal activity, which would explain their traditional use against insect pests of fields and food crops in Burundi. Keys words: Pesticide plant, Tithonia diversifolia, Solanum aculeastrum, maceration, insect pests
Description
Mémoire présenté et défendu en vue de l’obtention du diplôme de Master en Sciences Chimiques Orientation : Contrôle et Analyses Chimiques