Infection of Anastrepha ludens (Diptera: Tephritidae) Adults During Emergence from Soil Treated with Beauveria bassiana Under Various Texture, Humidity, and Temperature Conditions
2017
Wilson, Willy M. | Ibarra, Jorge E. | Oropeza, Azucena | Hernández, María Angelica | Toledo-Hernández, Ricardo Alberto | Toledo, Jorge
Anastrepha ludens (Loew) (Diptera: Tephritidae) is a major pest of mango and citrus in Mexico. It is usually controlled by applying several strategies in a holistic approach. The entomopathogenic fungus Beauveria bassiana (Bals.-Criv.) Vuill. (Cordycipitaceae) is a biocontrol agent that infects adults of many tephritids pests including A. ludens. In this work, we carried out 4 experiments with the objective of estimating the mortality of A. ludens adults when different conidial concentrations of the fungus B. bassiana were applied to the soil at different humidity, texture, and temperature conditions under controlled laboratory conditions. In a first experiment, mortality ranged from 38.3 to 79.8%, with the highest mortality occurring at a concentration of 800 mg of formulated conidia per kg of soil, while the lowest mortality was recorded at a concentration of 400 mg/kg. In a second experiment, when soils with different texture were investigated at 12% humidity, the pathogenicity of B. bassiana on A. ludens adults was similar in sandy clay soil and sandy loam (64.0% mortality), but was lower in sandy soil with 36.0% mortality. In a third experiment on humidity tests, fly mortality of A. ludens adults ranged from 43.0 to 79.8%, showing the highest mortality at 12% soil humidity and the lowest at 21%. Mortality was similar between 15 to 35 °C (>83%). Emergence of A. ludens adults in the controls ranged between 94.5 and 98.3%. The soil humidity was the major factor that significantly affected fungal efficacy. The study demonstrated the potential of using B. bassiana applied to the soil for management of A. ludens and other tephritids. However, B. bassiana must be evaluated under field conditions before recommendations can be made.
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