Interaction of Beauveria bassiana and Metarhizium anisopliae with chlorpyrifos ethyl and spinosad in Spodoptera frugiperda larvae

• Published in: Pest management science Vol. 74; no. 9; pp. 2047 - 2052
• Main Authors: Rivero‐Borja, Maribel, Guzmán‐Franco, Ariel W, Rodríguez‐Leyva, Esteban, Santillán‐Ortega, Candelario, Pérez‐Panduro, Alejandro
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.09.2018; Wiley Subscription Services, Inc
• Subjects: Agricultural practices; Antagonism; Beauveria bassiana; Cadavers; Chlorpyrifos; chlorpyrifos ethyl; Entomopathogenic fungi; Environmental impact; Environmental management; fall armyworm; FAW; Fungi; Insecticide resistance; Insecticides; insecticide–fungus interactions; Integrated pest management; Larvae; Metarhizium anisopliae; Mortality; Organic chemistry; Pest control; Pesticides; Pests; Spinosad; spinosines; Spodoptera frugiperda; Sporulation; entomopathogenic fungi; fall armyworm; integrated pest management; insecticide-fungus interactions; FAW; chlorpyrifos ethyl; spinosines
• DOI: 10.1002/ps.4884
• ISSN: 1526-498X

BACKGROUND The high natural resistance of the fall armyworm (FAW) to entomopathogenic fungi and the speed at which it develops resistance to chemical insecticides make it difficult to control in several crops where it is a key pest. The aim of the study was to improve mortality by combining a 50% lethal concentration of chlorpyrifos ethyl or spinosad with the entomopathogenic fungus Beauveria bassiana (Bb88) or Metarhizium anisopliae (ETL). RESULTS Three main results were obtained. (i) Both insecticides improved the performance of the fungus when the insecticide and fungus were applied simultaneously and when spinosad preceded fungi. In control larvae treated with fungi, <1% of larvae showed fungal sporulation, but under simultaneous application of the fungus with chlorpyrifos or spinosad, 31 and 47% did so, with 68 and 93% of cadavers showing sporulation, respectively. (ii) Synergistic mortality was observed when Bb88 and spinosad were applied simultaneously, which resulted in 34% more dead larvae than the spinosad control (44%). Finally, (iii) antagonism occurred when Bb88 was applied before chlorpyrifos, when Bb88 and chlorpyrifos were applied simultaneously, and when ETL was applied before chlorpyrifos, which reduced larval mortality by 27, 31 and 19%, respectively. CONCLUSION The synergistic mortality and improved fungal performance observed here support the hypothesis that combinations of low insecticide doses and entomopathogenic fungi can enhance integrated pest management programs and reduce the environmental impact of insecticides. Antagonism shows that some particular combinations and application sequences may produce disadvantages in pest control. © 2018 Society of Chemical Industry Spinosad or chlorpyrifos (LC50), applied simultaneously with Metarhizium anisopliae or Beauveria bassiana to FAW larvae, improved fungal infectivity and even produced synergistic mortality, while antagonism resulted when fungi preceded chlorpyrifos.