An at-leg pellet and associated Penicillium sp. provide multiple protections to mealybugs

作者：Z Q Li, Haojie Tong, Meihong Ni, Yiran Zheng, Yang Xinyi, Tan Yumei, Zihao Li, Mingxing Jiang · 发表于：Communications Biology · 年份：2024 · DOI：10.1038/s42003-024-06287-2 · 被引用次数：2 · 研究领域：Entomopathogenic Microorganisms in Pest Control、Research on scale insects、Insect symbiosis and bacterial influences

Beneficial fungi are well known for their contribution to insects' adaptation to diverse habitats. However, where insect-associated fungi reside and the underlying mechanisms of insect-fungi interaction are not well understood. Here, we show a pellet-like structure on the legs of mealybugs, a group of economically important insect pests. This at-leg pellet, formed by mealybugs feeding on tomato but not by those on cotton, potato, or eggplant, originates jointly from host secretions and mealybug waxy filaments. A fungal strain, Penicillium citrinum, is present in the pellets and it colonizes honeydew. P. citrinum can inhibit mealybug fungal pathogens and is highly competitive in honeydew. Compounds within the pellets also have inhibitory activity against mealybug pathogens. Further bioassays suggest that at-leg pellets can improve the survival rate of Phenacoccus solenopsis under pathogen pressure, increase their sucking frequency, and decrease the defense response of host plants. Our study presents evidences on how a fungi-associated at-leg pellet provides multiple protections for mealybugs through suppressing pathogens and host defense, providing new insights into complex insect × fungi × plant interactions and their coevolution.