Sustainable management of potato tuber moth in storages using entomopathogenic fungi and an ectoparasitic mite.

Background: The potato tuber moth (PTM), Phthorimaea operculella, is an economically important pest of potato crops worldwide. So far, the application of chemical pesticides is the major measure to manage PTM, but it induces serious deleterious impacts on the environment and human health. Here, we screened the entomopathogenic fungi that are lethal to PTM, and tested their sublethal impacts on PTM development, mortality, and reproduction as well as that of ectoparasitic mite Pyemotes zhonghuajia, a natural enemy of PTM.

Results: Among 13 tested entomopathogenic fungal strains in three genera, Beauveria Vuillemin, Cordyceps Fries, and Talaromyces Benjamin, Cordyceps fumosorosea (strain KY1136) and Beauveria bassiana (strain KY1115) caused a significantly higher mortality in PTM eggs, larvae, and pupae. Median lethal concentration (LC) of both strains prolonged PTM immature development, shortened adult longevity, and reduced fecundity and life table parameters in terms of intrinsic rate of increase (r), net reproductive rate (R), and finite rate of increase (λ). The LC value of KY1136 (1.9 × 10 spores/mL) was lower than that of KY1115 (9.0 × 10 spores/mL), indicating the greater potential for biological control of PTM by KY1136. Both strains had no significant impact on P. zhonghuajia survival and reproduction. Increasing P. zhonghuajia density reduced PTM feeding and pupation rate, while the combined application of P. zhonghuajia and entomopathogenic fungi had no additional effect in inhabiting PTM feeding and pupation.

Conclusion: Entomopathogenic fungal strains Cordyceps fumosorosea KY1136 and Beauveria bassiana KY1115 are the potential biological control agents of PTM, but do not impose a negative impact on the natural enemy. Our study provides insights into the integrated pest management of PTM by combining the entomopathogenic fungi and an ectoparasitic mite. © 2024 Society of Chemical Industry.