Submission of nuclear and kinetoplast sequences of trypanosomatids associated to two quarantine populations of the invasive stinkbug Bagrada hilaris

Authors: TANNIERES, MELANIE - European Biological Control Laboratory (EBCL); BON, MARIE-CLAUDE - European Biological Control Laboratory (EBCL); Grodowitz, Michael

Submitted to: Genbank
Publication Type: Database / Dataset
Publication Acceptance Date: 3/8/2022
Publication Date: 4/21/2024
Citation: Tannieres, M., Bon, M., Grodowitz, M.J. 2024. Submission of nuclear and kinetoplast sequences of trypanosomatids associated to two quarantine populations of the invasive stinkbug Bagrada hilaris. Genbank. OM938406 to OM938451.

Interpretive Summary: Bagrada hilaris, commonly known as the bagrada bug, is an invasive pest of economically important crops in the United States. It mainly attacks plants in the Brassicaceae, the mustard family of flowering plants. But it also has a relatively large host range. During microscopic observation, a protozoan with a long moving tail called a flagellum, was discovered in the alimentary canal of many specimens. These organisms, known as trypanosomatids, are responsible for several important human, livestock and plant diseases and are transmitted by insect vectors. However, the vast majority of trypanosomatids only infect insects such as stink bugs. DNA analysis indicated that these parasites belong to the genus Blastocrithidia and may represent a new species. It also showed that two Bagrada hilaris populations (from South Africa and the U.S.) reared in quarantine harbors the same parasites. It is thus possible that trypanosomatids were introduced in the U.S with Bagrada hilaris. Although most trypanosomatids have no or very little effect on their insect host, these parasites can be easily transmitted via ingestion of infected fecal matter from other insects and other food sources, raising concern of infection of insect species native to the U.S. Their life cycle, transmission pathway, and the impact of these trypanosomatids on the fitness of the bagrada bug and potential other insect hosts are unknown and additional research are warranted. A better understanding of the trypanosomatids and bagrada bug interaction could lead to the identification of a new mode of biological control for the bug.

Technical Abstract: Bagrada hilaris, commonly known as the bagrada bug, is an invasive pest of economically important crops in the United States. It mainly attacks plants in the Brassicaceae, the mustard family of flowering plants but it also has a relatively large host range. It has been targeted for classical biocontrol and several biocontrol agents are under investigation. During observation of bagrada specimen under the microscope, parasites with a flagellum were observed. These organisms, known as trypanosomatids, are responsible for several important human, livestock and plant diseases and are transmitted by insect vectors. However, the vast majority of trypanosomatids only infect insects such as stink bugs. Parasites were then detected in two quarantine populations originated from South Africa and the U.S. Morphological examination of these parasites under a microscope revealed the presence of particular structures called cyst-like amastigotes described in two different genera, but it did not yield a definitive identification. It is clear nowadays that trypanosomatid taxonomy previously based on morphological characteristics must also rely on DNA analysis. Whereas the nuclear 18S small subunit ribosomal RNA (SSU) is a commonly used molecular marker for trypanosome identification and phylogenies, the kinetoplast spliced leader (SL) RNA has proven suitable to distinguish closely related trypanosomatids. Sequences of the two molecular markers were thus generated from Bagrada host individuals from both populations. Genetic distances within and between the parasites infecting the two quarantine populations are low and compatible with the intraspecific distance observed in other Blastocrithidia species, indicating that both Bagrada populations harbor the same parasite. All sequences were compared to available sequences in the online Genbank database. Homology search revealed that these parasites belong to the genus Blastocrithidia and probably represent a new species. Sequences were deposited in Genbank as Blastocrithidia sp. under Accession number (OM938406-OM938451). Here we report for the first time the occurrence of Blastocrithidia sp. (Kinetoplastea, Trypanosomatidae) in different populations of Bagrada bug. Their life cycle, transmission pathway, and the impact of these trypanosomatids on the fitness of the bagrada bug and potential other insect hosts are unknown and additional research are warranted. A better understanding of the trypanosomatids and bagrada bug interaction could lead to the identification of a new mode of biological control for the bug.