2025/10/30 by Alison Kryger, Kayla Huang, Kayhan Tabrizifard +3 · 1 voice
Agricultural and Biological Sciences · Environmental Science · #Insect Utilization and Effects #Insects and Parasite Interactions #Physiological and biochemical adaptations
paper · pdf · doi:10.1111/eth.70026
openalex created_date 2025/10/30 · openalex publication_date 2025/10/30 · openalex updated_date 2026/07/22
ABSTRACT Aggregation behavior in arthropods is often a response to environmental stressors, particularly desiccation risk. While this is well documented in small‐bodied and larval arthropods, less is known about whether aggregation behavior provides similar benefits to adult and/or large‐bodied insects. Here, we investigate whether aggregation behavior in adult Madagascar hissing cockroaches ( Gromphadorhina portentosa ), a large insect species, is modulated by ambient relative humidity (RH). We exposed mixed‐sex groups of adult cockroaches to alternating high (75%–90%; “wet‐season”) and low (50%–65%; “dry‐season”) RH in a controlled laboratory setting and measured aggregation behavior over multiple weeks. Aggregation was significantly more likely to be observed under low RH, with a greater proportion of individuals aggregating. RH did not affect the sex ratio of aggregations. These results support the hypothesis that aggregation behavior in adult G. portentosa is, at least in part, a plastic and adaptive response to arid conditions, likely enhancing water retention by creating a humid microenvironment. Our findings highlight the importance of behavioral plasticity in large‐bodied insects facing fluctuating environmental conditions and suggest that increasing aridity due to climate change has the potential to impact the ecologies of G. portentosa and other similarly large, forest‐floor arthropods.