The Brown Marmorated Stink Bug (Halyomorpha halys Stål, 1855) as a Potential Biological Vector of Aflatoxigenic Fungi Under Climate Change

Abstract

Climate change is intensifying ecological instability in agricultural ecosystems, altering pest distribution and increasing the risk of fungal contamination and mycotoxin accumulation in crops. Among emerging threats, the invasive brown marmorated stink bug Halyomorpha halys has rapidly expanded across Europe, including Croatia. The species is polyphagous, and in the ripening of most plant crops, it accounts for a significant population and causes extensive plant damage. This study investigates the capacity of H. halys to disseminate mycotoxigenic fungi, with an emphasis on aflatoxin B1 (AFB1) and ochratoxin A (OTA) producers. One hundred adult H. halys individuals were collected from maize ears in Osijek, Croatia, in August 2023. Fungal propagules washed from their surfaces were inoculated on PDA and MEA media. A total of 212 pure fungal cultures were obtained, of which 202 belonged to the genera Aspergillus and Penicillium. Molecular identification using β-tubulin (BenA) gene sequencing revealed six Aspergillus and six Penicillium species, forming two well-supported phylogenetic clades. Aspergillus parasiticus was the most dominant species. Mycotoxin screening confirmed AFB1 production in 20 isolates, all identified as A. parasiticus, while no OTA-producing strains were detected. The predominance of aflatoxigenic species on H. halys indicates that it may play a previously underrecognized role in the dispersal of mycotoxigenic fungi in agroecosystems.