Articles
Efficacy and persistence of the entomopathogenic fungi and nematodes on walnut husk fly (Rhagoletis completa) in California
Article number
1420_36
Pages
267 – 274
Language
English
Abstract
The economic damage caused by the infestation of walnut husk fly, Rhagoletis completa Cresson, can be significant.
WHF is a severe pest of commercially grown walnuts in California, United States.
The WHF larvae feed on fruit husks and can cause shriveling and darkening of walnut kernels or shell staining.
WHF control in walnut orchards involves multiple applications of synthetic insecticides throughout the summer when adults emerge and oviposit in the fruit husk.
This approach can increase the risk of secondary or other pests’ resurgence because of the detrimental impacts on the natural enemies and is not sustainable.
Therefore, we conducted studies to explore non-chemical pesticide alternatives, i.e., entomopathogens, that are more IPM-friendly in managing WHF populations in the orchard.
In the study, we found that two entomopathogenic nematode species caused significantly higher mortality of walnut husk fly larvae compared to the control and entomopathogenic fungus treatment in the laboratory studies.
Field-applied entomopathogens persisted in the field for at least four weeks.
Further field studies have been devised to target the ready-to-pupate larvae in the fall and teneral adults during their emergence in the summer to confirm if entomopathogens can be effective against WHF. These bio-based tools can be an effective part of the WHF management program to establish sustainable pest management (SPM) in California walnuts.
WHF is a severe pest of commercially grown walnuts in California, United States.
The WHF larvae feed on fruit husks and can cause shriveling and darkening of walnut kernels or shell staining.
WHF control in walnut orchards involves multiple applications of synthetic insecticides throughout the summer when adults emerge and oviposit in the fruit husk.
This approach can increase the risk of secondary or other pests’ resurgence because of the detrimental impacts on the natural enemies and is not sustainable.
Therefore, we conducted studies to explore non-chemical pesticide alternatives, i.e., entomopathogens, that are more IPM-friendly in managing WHF populations in the orchard.
In the study, we found that two entomopathogenic nematode species caused significantly higher mortality of walnut husk fly larvae compared to the control and entomopathogenic fungus treatment in the laboratory studies.
Field-applied entomopathogens persisted in the field for at least four weeks.
Further field studies have been devised to target the ready-to-pupate larvae in the fall and teneral adults during their emergence in the summer to confirm if entomopathogens can be effective against WHF. These bio-based tools can be an effective part of the WHF management program to establish sustainable pest management (SPM) in California walnuts.
Publication
Authors
J.P. Rijal, S. Gyawaly
Keywords
entomopathogen, walnut husk fly, Rhagoletis completa, nematodes
Groups involved
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