Browsing by Author "Tumuhaise, Venansio"

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An atoxigenic L-strain of Aspergillus flavus (Eurotiales: Trichocomaceae) is pathogenic to the coffee twig borer, Xylosandrus compactus (Coleoptera: Curculionidea: Scolytinae)
(Environmental Microbiology Reports, 2018-10-11) Mukasa, Yosia; Kyamanywa, Samuel; Sserumaga, Julius P.; Otim, Michael; Tumuhaise, Venansio; Erbaugh, Mark; Egonyu, James P.
This study isolated and evaluated virulence of fungal entomopathogens of Xylosandrus compactus – an important pest of Robusta coffee in Sub-Saharan Africa. A survey was conducted in five farming systems in Uganda to isolate entomopathogens associated with X. compactus. Four fungal isolates were screened for virulence against X. compactus in the laboratory at 1 × 107 conidia ml−1 where an atoxigenic L-strain of A. flavus killed 70%–100% of all stages of X. compactus compared with other unidentified isolates which caused 20%–70% mortalities. The time taken by A. flavus to kill 50% of X. compactus eggs, larvae, pupae and adults in the laboratory was 2–3 days; whereas the other unidentified fungal isolates took 4–7 days. The concentrations of A. flavus that killed 50% of different stages of X. compactus were 5 × 105, 12 × 105, 17 × 105 and 30 × 105 conidia ml−1 for larvae, eggs, pupae and adults respectively. A formulation of A. flavus in oil caused higher mortalities of X. compactus larvae, pupae and adults in the field (71%–79%) than its formulation in water (33%–47%). The atoxigenic strain of A. flavus could therefore be developed into a safe biopesticide against X. compactus.
First report of field efficacy and economic viability of metarhizium anisopliae-ICIPE 20 for tuta absoluta (Lepidoptera: Gelechiidae) management on tomato
(MDPI Sustainability, 2022-11) Fred, Kabaale P.; Tumuhaise, Venansio; Tinzaara, William; Turyasingura, Geoffrey; Subramanian, Sevgan; Khamis, Fathiya Mbarak; Akutse, Komivi Senyo
Eco-friendly pest control options are highly needed in food crop production systems to mitigate the hazards of synthetic chemical pesticides. Entomopathogenic fungal biopesticides— Metarhizium anisopliae strains ICIPE 20 (oil-formulation containing 1.0 × 109 conidia/mL) and ICIPE 69 (commercialized biopesticide known as Mazao Campaign®)—were evaluated against Tuta absoluta on tomato through inundative foliar spray and compared with the commonly used pesticide Dudu Acelamectin 5% EC (Abamectin 20 g/L + Acetamiprid 3%) and untreated plot. All the treatments were arranged in a randomized complete block design with three replicates. The field experiments were conducted for two consecutive cropping seasons in Mukono district, Uganda. Tuta absoluta infestation, injury severity on leaves and fruits, fruit yield loss, marketable fruit yield gain and costbenefit ratio of the treatments were assessed. The results during both seasons showed a significant lower fruit yield loss in M. anisopliae ICIPE 20-treated plots compared to untreated plots, with a marketable fruit yield gain exceeding 22% and a cost–benefit ratio greater than 2.8 (BCR~3). Dudu Acelamectin 5% EC outperformed all the other treatments, but needs to be considered with caution due to its non-target effect and resistance development, whereas M. anisopliae ICIPE 69 performed the least well. In addition, the findings showed the high degree of efficacy and economic viability of these biopesticides as a potential T. absoluta control option in the field. However, it is important to Academic Editor: Sean Clark Received: 23 September 2022 Accepted: 7 November 2022 Published: 10 November 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). further explore different formulations of these eco-friendly biopesticides, inoculum delivery approach, application frequency, their effectiveness in different agro-ecological zones and compatibility with commonly used pesticides in tomato production systems for sustainable management of T. absoluta.
Xanthomonas bacteriophages: a review of their biology and biocontrol applications in agriculture
(BMC Microbiology, 2021-10-25) Nakayinga, Ritah; Makumi, Angela; Tumuhaise, Venansio; Tinzaara, William
Phytopathogenic bacteria are economically important because they affect crop yields and threaten the livelihoods of farmers worldwide. The genus Xanthomonas is particularly significant because it is associated with some plant diseases that cause tremendous loss in yields of globally essential crops. Current management practices are ineffective, unsustainable and harmful to natural ecosystems. Bacteriophage (phage) biocontrol for plant disease management has been of particular interest from the early nineteenth century to date. Xanthomonas phage research for plant disease management continues to demonstrate promising results under laboratory and field conditions. AgriPhage has developed phage products for the control of Xanthomonas campestris pv. vesicatoria and Xanthomonas citri subsp. citri. These are causative agents for tomato, pepper spot and speck disease as well as citrus canker disease. Phage-mediated biocontrol is becoming a viable option because phages occur naturally and are safe for disease control and management. Thorough knowledge of biological characteristics of Xanthomonas phages is vital for developing effective biocontrol products. This review covers Xanthomonas phage research highlighting aspects of their ecology, biology and biocontrol applications.