Population genomics of the neotropical stink bug, Euschistus heros: The most important emerging insect pest to soybean in Brazil

Authors: ZUCCHI, MARIA - Agencia Paulista De Tecnologia Dos Agronegocios/saa-Sp; CORDEIRO, ERICK - Universidade De Sao Paulo; WU, XING - University Of Illinois; MARISE LAMANA, LETICIA - State University Of Ponta Grossa; BROWN, PATRICK - University Of California, Davis; MANJUNATHA, SHILPA - University Of Illinois; GOMES VIANA, JOAO PAULO - University Of Illinois; OMOTO, CELCO - Universidade De Sao Paulo; PINHEIRO, J. BALDIN - Universidade De Sao Paulo; Clough, Steven

Submitted to: Frontiers in Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2019
Publication Date: 10/31/2019
Citation: Zucchi, M.I., Cordeiro, E., Wu, X., Marise Lamana, L., Brown, P.J., Manjunatha, S., Gomes Viana, J., Omoto, C., Pinheiro, J., Clough, S.J. 2019. Population genomics of the neotropical stink bug, Euschistus heros: The most important emerging insect pest to soybean in Brazil. Frontiers in Genetics. 10:1035. https://doi.org/10.3389/fgene.2019.01035.
DOI: https://doi.org/10.3389/fgene.2019.01035

Interpretive Summary: Populations of insect pests of crops, such as the neotropical brown stink bug (Euschistus heros), an emerging pest of soybean, can spread by multiple means, and in response to numerous changes to the environment. To better assess the risk of the spreading and increases in pest populations, it is necessary to assess the local level of the genetic diversity of the pest, and to determine how the species diversity is distributed across different areas, and to then examine how natural selection is affecting the natural variation. We conducted such a study of Euschistus heros by generating ~60,000 single-nucleotide polymorphic DNA markers across the Euschistus heros genome, and used this marker data to study population dynamics of this pest. We found the populations of this pest had high levels of genetic diversity, but that these levels of diversity were different in different regions of Brazil. Our results showed strong genetic structures separating northern and southern regions of the country, and a very distinct hybrid zone at the central region. The analyses also suggested some genes that might be associated with these differences in selection. We discuss the implications of this finding to the management of emerging pests in agriculture, particularly in the context of large areas of monoculture, such as soybean.

Technical Abstract: Recent changes in soybean management, like the adoption of transgenic crops and no-till farming, in addition to the expansion of cultivated areas into new virgin frontiers, are some of the factors hypothesized to explain the rise of secondary pests, such as the neotropical brown stink bug, Euschistus heros, in Brazil. To better assess the risk of increased pests like E. heros, and to determine probabilities for insecticide resistance spreading or impact of a new plant variety, it is necessary first to assess the local level of the genetic diversity of the pest, and to determine how the species diversity is distributed across different areas and how natural selection is acting upon the natural variation. Using the genotyping by sequencing technique, we generated ~60,000 single-nucleotide polymorphisms (SNPs) distributed across the E. heros genome. The SNP data can be used to investigate issues related to this emerging pest. We found that E. heros populations presented high levels of genetic diversity with slightly higher values at the central locations in Brazil. Our results also showed strong genetic structures separating northern and southern parts of the range (FST=0.22 p-value=0.000) with a very distinct hybrid zone at the central region. The analyses also suggested the possibility that transcription factors, metabolic enzymes, and the GABA channels might play a role in selection. We discuss the implication of this finding to the management of emerging pests in agriculture, particularly in the context of large areas of monoculture such as soybean and cotton.