Prospects of indigenous fungi as novel biological control agents of thrips (Frankliniella occidentalis Pergande, 1895) on tomato (Solanum lycopersicum L.) in vivo

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Michael Wabukala Barasa*, Ruth Kahuthia-Gathu, Maina Mwangi and Waceke Wanjohi

Abstract

Tomato (Solanum lycopersicum L.) is an important horticultural crop in Kenya. Its production is constrained by many factors, among them arthropod pests and diseases. In response, farmers rely on synthetic pesticides, which lead to contamination of the produce, pest resistance and pollution of the environment hence there is need to identify safer, affordable alternatives. Biological control is considered safe, self-sustaining and cost effective. This study was aimed at determining the effectiveness of indigenous fungi in managing Western flower thrips Frankliniella occidentalis on tomato. Efficacy trials were conducted in farmer’s fields in Bungoma County, Kenya between March and November 2018. Treatments included fungal isolates Trichoderma harzianum, Gliocladium virens, Verticillium spp., Paeciliomyces victoriae and Fusarium oxysporum selected after in vitro screening. These were compared to commercial fungus Beauveria basssiana, a synthetic pesticide imidacloprid and untreated control. Treatments were replicated four times, arranged in a randomized complete block design. Data collected on population of thrips and the yield of tomatoes were subjected to Analysis of Variance (ANOVA). Means were separated using Student Newman-Keuls (SNK) test at p≤0.05. In the first season at Bukonoi, F. oxysporum significantly (p<0.05) recorded the least (38.1) mean number of thrips compared to the untreated control (89.2). At Cheptais, F. oxysporum and T. harzianum treated plots significantly (p<0.05) recorded the least mean number of thrips of 48.1 and 20.5 in the first and second season, respectively. Higher yields of 4.9 t ha-1 and 29.5 t ha-1 were obtained from plots treated with T. harzianum in the first and second season, respectively. The findings of this study demonstrated that F. oxysporum and T. harzianum have the potential to be developed as fungal biopesticides for management of thrips on tomato crop. However, large scale field trials are warranted to validate the effectiveness of these fungal isolates.


Key words: Biopesticides, Frankliniella occidentalis, Fusarium oxysporum, Solanum lycopersicum, Trichoderma harzianum.