Environmental Response of Cordyceps fumosorosea and Its Biocontrol Potential Against the Potato Insect Pest Phthorimaea operculella (Zeller)

Abstract

The potato tuber moth (PTM), Phthorimaea operculella, is a globally distributed pest that causes damage to potato crops both in the field and during storage. Although chemical insecticides are widely employed to control this pest, their overuse has resulted in the development of resistance in PTM populations. Entomopathogenic fungi (EPF) represent a promising alternative to chemical insecticides in integrated management of insect herbivores. This study evaluated the potential of C. fumosorosea strain YNKM210801 for controlling PTM by assessing its pathogenicity across all life stages and key ecophysiological characteristics, followed by spatial distribution modelling across China. The fungus induced high adjusted mortality across all life stages (92.21% in eggs, 83.36% in larvae, and 96.67% in pupae) at a concentration of 1 × 10⁸ conidia/mL. Notably, the median lethal concentration (LC₅₀) values for eggs (3.69 × 10⁴ conidia/mL) and pupae (2.34 × 10⁴ conidia/mL) were significantly lower than that for larvae (4.78 × 10⁶ conidia/mL). The strain exhibited optimal growth at 20°C–25°C and pH 6–8, with maximal conidial production under a 16 h light: 8 h dark cycle. In terms of stress tolerance, it showed moderate thermotolerance (GT₅₀ = 16.81 min at 45°C) and UV-B resilience (half-life = 2.32 h at 592.3 μW/cm²). Spatial modelling indicated its high-efficacy zones for PTM control across most of China from April to October. Our study demonstrates the potential of C. fumosorosea YNKM210801 as a biopesticide for sustainable P. operculella management in diverse Chinese potato cropping systems.