Examinando por Materia "Biological control"

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Efficiency of entomopathogenic bacteria and fungi on Oligonychus yothersi in vitro and on Persea americana Mill. plants
(Facultad de Agronomía de la Universidad del Zulia,, 2023-11-03) Parco Quinchori, Jhimy Andy; Valverde Rodriguez, Agustina; Cornejo, Antonio; Briceño, Henry; Barrionuevo, Laura; Romero, Javier
In the germplasm bank of 22 varieties of avocado (Persea Americana Mill.) belonging to the Fruit Horticultural Institute Investigation, HermilioValdizan National University (UNHEVAL)-Peru, it is common to observe a high population of the species Oligonychusyothersi, a phytophagous mite harmful to the crop. Controls with commercial acaricides are restricted in place, due to the presence of beehives installed in adjacent plots. The objective of this study was to evaluate the effect of four commercial formulations containing strains of Metarhiziumanisopliae and Beauveria bassiana and the toxins of Bacillussubtilis, Bacillus thuringiensis var.kurstaki (Btk) for the control of O. yothersi. The entomopathogenic products were evaluated in the field applying a randomized complete block design with five treatments and three replicates. In the laboratory, 500 adult mites were selected, placing 100 mites per Petri dish with three repetitions per treatment. It was found that the formulation Bacillus thuringiensis var.kurstaki under field conditions reduced the population incidence of mites by up to 98.07% in 49 days. In the laboratory, the B. subtilis and M. anisopliae formulations caused 100% mortality six days after application proving to be efficient control alternatives.
Pathogenicity of Heterorhabditis bacteriophora in ultraviolet light–irradiated agar suspension on Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae
(Georgia Entomological Society, 2023-09-08) Pérez Tesén, Edgar Darwin; Rodas Adrianzén, Jennifher Elizabeth; Chávez Cabrera, Alexander; Neira de Perales, María Elena
Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is an economically important pest of variety of crops, including maize (Zea mays L.), rice (Oryza sativa L.), and cotton (Gossypium spp.). Conventional chemical insecticides are usually used for management of this pest; however, a viable alternative is the use of microbial agents or their biological products, such as entomopathogenic nematodes. Their efficacy, however, is affected by abiotic conditions including ultraviolet (UV) light and desiccation. It is therefore necessary to develop formulations that preserve or extend the viability of the agent or product while facilitating ease of application. This laboratory study was conducted to determine the pathogenicity of the nematode Heterorhabditis bacteriophora (Poinar) against S. frugiperda third-instar larvae. Infective juveniles (IJs) of the nematode were tested at a concentration of 350 IJs/ml in two substrates (water and 0.1% [w/v] agar suspension) with four periods of exposure (0, 5, 10 and 15 min) to UV radiation at 253.7 nm. Each of the eight treatments included 40 larvae, with each treatment replicated three times in a completely randomized design (two factors of type of medium and UV exposure time). We determined that the 0.1% (w/v) agar suspension, compared with the water substrate, protected the IJs from harmful UV light and thus improved the survival and pathogenicity of the IJs against third-instar S. frugiperda.