Open field evaluation of Aculodes altamurgensis, a recently described eriophyid species associated with medusahead (Taeniatherum caput-medusae)

Authors: CRISTOFARO, MASSIMO - Biotechnology And Biological Control Agency; ROSELLI, GERARDO - Biotechnology And Biological Control Agency; MARINI, FRANCESCA - Biotechnology And Biological Control Agency; DE LILLO, ENRICO - University Of Bari; PETANOVIC, RADMILA - University Of Belgrade; VIDOVIC, BILJANA - University Of Belgrade; AUGE, MATTHEW - Biotechnology And Biological Control Agency; Rector, Brian

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2019
Publication Date: 1/8/2020
Citation: Cristofaro, M., Roselli, G., Marini, F., de Lillo, E., Petanovic, R., Vidovic, B., Auge, M., Rector, B.G. 2020. Open field evaluation of Aculodes altamurgensis, a recently described eriophyid species associated with medusahead (Taeniatherum caput-medusae). Biological Control. 30(4):339-350. https://doi.org/10.1080/09583157.2019.1711021.
DOI: https://doi.org/10.1080/09583157.2019.1711021

Interpretive Summary: Medusahead (Taeniatherum caput-medusae) is an annual grass from the Mediterranean region that is an invasive noxious weed in many western states and the target of a biological control program led by USDA-ARS. During an exploration carried out in 2014, a new species of eriophyid mite, Aculodes altamurgiensis was found on medusahead in southern Italy by an ARS scientist and subsequently found by the ARS scientist in Serbia and Bulgaria; the same mite has also been collected in Greece, Turkey and Iran by collaborating scientists. In 2016, an open-field test was carried out by collaborating scientists in Rome, Italy, testing the mite on 11 different grass species and/or biotypes, including 5 populations of medusahead (3 from USA, 2 from Italy), 5 crop species (bread wheat, durum wheat, oat, barley, and maize) and one wild grass species (foxtail barley). The mite was able to reproduce only on the target weed species, medusahead, providing impetus to continue with more intensive studies to assess this mite’s potential as a biocontrol target of medusahead. However, the biotype of the mite that was used in the field test, from southern Italy, had variable colonization success on the five different medusahead biotypes, including low colonization on an invasive biotype collected in California. Additional tests will be conducted on other biotypes of the mite (not from southern Italy) to determine if they will have more uniform high colonization rates on different medusahead populations, especially on invasive medusahead populations from the USA.

Technical Abstract: Medusahead (Taeniatherum caput-medusae) is an annual grass native to Central Asia and the Mediterranean region. It is a noxious, invasive weed in much of western North America. As such, it is the target of a classical biological control program established by USDA-ARS. During explorations carried out in 2014 a new species of eriophyid mite, Aculodes altamurgiensis, was discovered on medusahead in southern Italy; it was also collected from medusahead in Bulgaria, Serbia, Turkey, and Iran in subsequent years. In the field A. altamurgensis has consistently been associated with the target weed while never having been detected from sympatric grass species (e.g. Stipa austroitalica, Avena sativa, Triticum durum, T. aestivum), suggesting that A. altamurgensis is highly specific to medusahead. An open-field host-specificity test was carried out in Rome, Italy in 2016 in which an Italian population of A. altamurgensis was infested onto 11 different grass genotypes, including five crop species and five different populations of medusahead (two from Italy and three populations that are invasive in the USA). The results suggest that A. altamurgiensis is highly specific to medusahead and merits further evaluation as a candidate for biological control of this invasive grass. However, the Italian population of A. altamurgiensis showed variable colonization rates on different medusahead populations, indicating that other A. altamurgiensis sources (e.g. from Serbia or Bulgaria) should also be tested to determine if they can colonize medusahead at more uniformly high rates, particularly on the targeted invasive populations in the USA.