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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #424205
Research Project: Novel Approaches for Managing Key Pests of Peach and Pecan

Location: Fruit and Tree Nut Research

Title: Effects of temperature and humidity on the presence and prevalence of a parasitic microfungus on an invasive ladybird

Author
item DE GROOT, MICHIEL - Ghent University
item SANTAMARIA, BRIANNA - Ghent University
item ADRIAENS, TIM - Research Institute For Nature And Forest (INBO)
item Cottrell, Ted
item MAES, DIRK - Radboud University
item SAKAKI, SAMANEH - University Of South Bohemia
item VERBEKEN, ANNEMIEKE - Ghent University
item NEDVED, OLDRICH - Czech Academy Of Sciences
item HAELEWATERS, DANNY - Czech Academy Of Sciences

Submitted to: Ecological Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2025
Publication Date: 9/17/2025
Citation: De Groot, M.D., Santamaria, B., Adriaens, T., Cottrell, T.E., Maes, D., Sakaki, S., Verbeken, A., Nedved, O., Haelewaters, D. 2025. Effects of temperature and humidity on the presence and prevalence of a parasitic microfungus on an invasive ladybird. Ecological Entomology. 51(1):86-97. https://doi.org/10.1111/een.70014.
DOI: https://doi.org/10.1111/een.70014

Interpretive Summary: Invasive species can significantly alter ecosystems. The multicolodred Asian lady beetle has become a widespread invasive species, and its interactions with natural enemies such as the ectoparasitic fungus Hesperomyces harmoniae remain insufficiently understood. Here, we investigate how temperature and humidity influence the ectoparasitic fungus. We tested low versus high relative humidity, and low versus high temperature. Our results indicate that high humidity increased both fungus prevalence and rate of development compared to the control. High temperature had a slight negative effect, whereas low humidity and low temperature had strong negative effects on both measures. The ectoparasitic fungus thrives best under moderately warm and humid conditions and that its prevalence may be constrained in drier or cooler environments.

Technical Abstract: Invasive species can significantly alter ecosystems, often through competitive dominance and indirect ecological effects. The multicolored Asian lady beetle (Harmonia axyridis) has become a widespread invasive species, and its interactions with natural enemies such as the ectoparasitic fungus Hesperomyces harmoniae remain insufficiently understood. Here, we investigate how temperature and humidity influence He. harmoniae prevalence and development on Ha. axyridis using controlled laboratory experiments. We tested different environmental conditions: low versus high relative humidity, and low versus high temperature. We assessed parasite prevalence (proportion of infected individuals) and rate of development (time to maturity of fungal thalli). Our results indicate that high humidity increased both parasite prevalence and rate of development compared to the control. High temperature had a slight negative effect, whereas low humidity and low temperature had strong negative effects on both measures. Our findings suggest that He. harmoniae thrives best under moderately warm and humid conditions and that its prevalence may be constrained in drier or cooler environments. Understanding the environmental factors influencing He. harmoniae dynamics provides insights into the role of abiotic conditions in shaping host-parasite interactions, with potential implications for the population ecology of Ha. axyridis in different climatic regions.