Occurrence of Arthropod Pests of Tomato and Efficacy of Entomopathogenic Fungi Against Frankliniella Occidentalis (Pergande) in Bungoma County, Kenya
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Date
2020-06
Authors
Barasa, Wabukala Michael
Journal Title
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Publisher
Kenyatta University
Abstract
Tomato Solanum lycopersicum L. is an important crop in Kenya. Arthropod pests are major constraints to its production. The pests make farmers to rely heavily on synthetic chemicals for control and this increases costs and pollution of the environment. The objective of this study was to assess the occurrence of arthropod pests of tomato and evaluate the effectiveness of native Kenyan fungi in managing thrips as an alternative to synthetic pesticides. A survey was carried out in Bungoma County and data collected from ninety farmers on tomato production practices, pests present, diseases and their management practices. In vitro studies were conducted to evaluate the effectiveness of native fungi against Frankliniella occidentalis collected from the tomato fields and maintained in the laboratory. The fungi were isolated from ninety soil samples from tomato fields and identified based on their vegetative and reproductive structures. Treatments included fungal isolates and a control; replicated four times arranged in a completely randomized design. The effect of the fungal isolates on F. occidentalis was evaluated by treating thrips with concentrations of 1.0 x107conidia ml-1. Data on mortality of F. occidentalis was recorded daily for 10 days after treatment. Field trials were conducted at Bukonoi and Cheptais in 2018 to determine the most virulent fungal antagonists. The fungi were Trichoderma virens 1, Trichoderma virens 2, Trichoderma afroharzianium, Fusarium solani and Fusarium oxysporum. Their efficacy was compared to Beauveria bassiana, synthetic pesticide Imidacloprid and a control (water). All treatments were applied weekly as foliar sprays commencing three weeks after transplanting of tomatoes until harvesting. Fungal antagonists were applied at a rate of 1.0 x108 cfu g-1. Treatments were replicated four times in a randomized complete block design. Data were collected on population of F. occidentalis and the yield. Survey data was analyzed using SPSS version 18.0 while data on in vitro and field trials were subjected to Analysis of Variance using SAS version 9.4. Means were separated using Student Newman-Keuls test at P≤0.05. Results revealed F. occidentalis (58.6%) as major pests of tomato and Ralstonia solanacearum disease (75%). The most frequently used chemicals were Imidacloprid (24.4%) and Mancozeb (17.2%). Only 2.4% of the growers used bio-pesticides. In vitro studies showed that T. virens, F. solani, F. oxysporum and T. afroharzianum were more virulent against F. occidentalis causing mortalities above 50%. The least mean number of F. occidentalis per flower at Bukonoi was observed on T. afroharzianum and F. oxysporum treated plots with 2.2 and 1.0 during long and short rainy season, respectively. At Cheptais, the lowest mean of F. occidentalis (2.4) was recorded on F. oxysporum and T. afroharzaianum (1.0), respectively. Tomato plots treated with T. afroharzianum gave the highest yield of 3.8 t/ha and 27.2 t/ha during the long and short rainy season at Bukonoi with a corresponding 0.3 t/ha and 12.3 t/ha at Cheptais, respectively. The findings showed that T. afroharzianium and F. oxysporum have potential for development as fungal-based bio-pesticides against F. occidentalis on tomato. Further studies should be done to determine the optimal conditions for effectiveness of F. oxysporum and T. afroharzianum
Description
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Crop Protection (Entomology option), Department of Agricultural Science and Technology, Kenyatta University.
June, 2020
Keywords
Occurrence, Arthropod Pests, Tomato, Efficacy of Entomopathogenic Fungi, Frankliniella Occidentalis (Pergande), Bungoma County, Kenya