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

ABSTRACT

Medusahead (Taeniatherum caput-medusae, Poales: Poaceae) 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 programme established by USDA-ARS. During explorations carried out in 2014 a new species of eriophyid mite, Aculodes altamurgiensis de Lillo & Vidovic, 2018 (Acari: Eriophyidae), 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 (Poales: Poaceae) 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 supported the previous observations 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 colonisation rates on different medusahead populations, indicating that populations of A. altamurgiensis from other regions should also be tested to determine if they can colonise medusahead at more uniformly high rates, particularly on the targeted invasive populations in the USA.

KEYWORDS:

• Classical biological control
• Eriophyidae
• host specificity
• invasive species
• mites
• weeds

Acknowledgements

The authors are grateful to all colleagues and friends who contributed the study in some way; many of them by collecting specimens and others in supporting our activities in various ways: Francesca Di Cristina, Silvietta Barlattani, Fabrizio Freda, Alessandra Paolini and Michèle Guedj (BBCA onlus, Rome, Italy) for technical support, collections and preliminary host range observations; and Lincoln Smith and Paul Pratt (USDA ARS, Albany, CA), René Sforza (USDA ARS EBCL-France), Vili Harizanova and Atanaska Stoeva (University of Plovdiv, Bulgaria), Carmine Genua (University of Rome), Valerio Mazzoni (Foundation Edmund Mach) and Sergio Musmeci (ENEA-Casaccia, Rome, Italy) for their scientific support. This work was supported by the USDI, Bureau of Land Management under Agreement L16PG00228.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability

The data that support the findings of this study are available from the corresponding author (BGR) upon reasonable request.

Additional information

Funding

This work was supported by U.S. Bureau of Land Management [grant number L16PG00228].