Browsing by Author "Mrosso, Secilia"

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Characterization of Secondary Metabolites Responsible for the Resistance of Local Tomato Accessions to Whitefly (Bemisia tabaci, Gennadius 1889) Hemiptera in Tanzania
(MDPI, 2022-11-15) Mrosso, Secilia; Ndakidemi, Patrick; Mbega, Ernest
Plants have developed mechanisms to cope with stresses in their environments as they grow in diverse settings. Such means include releasing plant defense compounds upon attacks by pests or other stressors. Plants with these characteristics are essential as a plant germplasm source for breeding resistance against herbivores and insect pests. Therefore, this study aimed to screen germplasms for whitefly resistance and characterize the secondary metabolites responsible for this. Thirty local tomato accessions were screened for resistance against whiteflies (Bemisia tabaci Gennadius) in the screen house located at Tanzania Plant Health and Pesticides Authority (PTHPA) between January and April 2021. From this screening, seven local tomato cultivars: TZA3729, TZA5554, TZA5545, TZA5562, TZA5552, TZA3177 and TZA5157, showed resistance, and one accession (TZA5496) that showed susceptibility to whiteflies (negative control) and accession V1030462 that was a standard (positive control) were selected for the subsequent experiments. The experiment was conducted in July–October 2021 in the screen house at TPHPA and repeated in January–April 2022 using a completely randomized block design with three replications. From this experiment, three accessions: TZA3729, TZA5562 and TZA5157, showed resistance against whiteflies. However, accession TZA3729 was more resistant than TZA5562 and TZA5157 when compared to the resistant accession V1030462. Therefore, these accessions were further screened for secondary metabolites responsible for resistance against herbivores and insect pests—in this case, whiteflies. The GS-MS methanol extract results showed accession TZA3729 to possess a wide array of secondary plant metabolites responsible for plant self-defenses, such as diterpenes, Tetraterpenes, alkaloids, carotenoids and fatty acid esters. Therefore, the study recommends accession TZA3729 as a source of tomato plant germplasm for breeding tomatoes resistant to whiteflies.
Farmers’ Knowledge on Whitefly Populousness among Tomato Insect Pests and Their Management Options in Tomato in Tanzania
(MDPI, 2023-02-13) Mrosso, Secilia; Ndakidemi, Patrick; Mbega, Ernest
Whitefly is a populous insect pest among tomato insect pests, causing significant crop loss through direct and indirect attacks. The current study aimed to assess the knowledge of tomato farmers on the populousness of whiteflies compared to other tomato insect pests and explore the management options available in their farming context in three tomato-growing regions, Arusha, Morogoro, and Iringa, in Tanzania. The study used a questionnaire to collect the data with backup information obtained through key informants’ interviews and focus group discussions. The study findings indicated whitefly to be populous among tomato insect pests. However, tomato farmers showed varying knowledge of whitefly aspects, including differing control options for the pest. Such findings indicated a knowledge gap between farmers’ understandings of the pest and their practices in fighting it compared to the standard and required practices in controlling the pest.
Survival Mechanisms and Management Challenges Associated with Silver Leaf Whitefly on Tomato in Africa: A Review
(Friends Science Publishers, 2022-04-30) Mrosso, Secilia; Ndakidemi, Patricka; Mbega, Ernest
Silver leaf whitefly (Bemisia tabaci Gennadius) (Hemiptera: Aleyrodidae) is a polyphagous winged insect pest that causes high yield losses in tomatoes and other vegetable crops globally. To combat the infestation by the silver leaf whitefly and other insects, tomato growers use cultural and synthetic chemical-based methods. However, the silver leaf whitefly continues to dominate the tomato production systems. Some of the reasons for such continued dominion by the silver leaf whitefly in tomato include among other reasons; little understanding of the mechanisms for survival of the insect pest by tomato production stakeholders which consequently results in difficulties in making appropriate pest management decisions, presence of diverse hosts, the ability of the silver leaf whitefly to develop resistance to synthetic pesticides and ineffective techniques used by tomato grower in combating the insect. Of these challenges, this review discusses the mechanisms for survival of the insect, current pest management options and recommendations for a way forward concerning the silver leaf whitefly management in Africa.