Cordyceps sp. WZFW1, a novel entomopathogenic fungus to control Ectropis grisescens (Lepidoptera: Geometridae)

Abstract

Ectropis grisescens is a notorious pest in tea plantations. The control of E. grisescens relies on synesthetic pesticides but the resurgence is always accompanied by increasing resistance. Therefore, it is crucial to use biological control to reduce the damage caused by E. grisescens. Here, we collected soil from a tea plantation, used Galleria mellonella as a bait insect and successfully isolated one entomopathogenic fungus. The isolated colony was initially identified as Cordyceps sp. using morphological observation. ITS-rDNA sequence amplification and sequencing, molecular database comparisons, and phylogenetic analysis proved this fungus as a new species and thus named Cordyceps sp. WZFW1. Further virulence test of Cordyceps sp. WZFW1 against E. grisescens was evaluated under laboratory conditions. Lethal concentration was 5.74 × 10⁶ spore/mL with a confidence level of 2.32 × 10⁶ ~ 1.79 × 10⁷ and lethal time was 2.98 days at 10⁸ spore/mL and 7.47 days at 10⁷ spore/mL, indicating Cordyceps sp. WZFW1 was effective at controlling E. grisescens. Our findings are significant as they contribute to the application of new entomopathogenic fungi (EPF) species as biocontrol agents, promoting eco-friendly pest management practices.