PCR based screening of nematodes and fungi associated with pupae of Lasioptera donacis Coutin (Diptera: Cecidomyiidae), a biological control agent of the giant reed

Authors: BON, MARIE-CLAUDE - European Biological Control Laboratory (EBCL); GUERMACHE, FATIHA - European Biological Control Laboratory (EBCL); DE SIMONE, DANIELE - Bbca-Onlus, Italy; CRISTOFARO, MASSIMO - Bbca-Onlus, Italy; VACEK, ANN - University Of Texas; Goolsby, John

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2018
Publication Date: 9/4/2018
Citation: Bon, M., Guermache, F., De Simone, D., Cristofaro, M., Vacek, A., Goolsby, J. 2018. PCR based screening of nematodes and fungi associated with pupae of Lasioptera donacis Coutin (Diptera: Cecidomyiidae), a biological control agent of the giant reed. Florida Entomologist. 101(3):505-507. https://doi.org/10.1653/024.101.0309.
DOI: https://doi.org/10.1653/024.101.0309

Interpretive Summary: The leaf miner Lasioptera donacis is a biological control agent of giant reed, which is an exotic and invasive weed of riparian habitats and irrigation canals of the Rio Grande River Basin and the southwestern U.S. Giant reed invasion leads to loss of biodiversity, catastrophic stream bank erosion, and reduced visibility for law enforcement activities on the U.S.-Mexico border. The leaf miner was recently permitted for release in the U.S. and Mexico. It was imported from Mediterranean Europe to the U.S. as pupae which were observed to be infested by nematodes. We used a molecular genetic method to diagnose precisely the presence of any nematode and fungi in pupae. This approach would allow ultimately to determine if a nematode-free population could be collected in the Mediterranean region and shipped safely to U.S.

Technical Abstract: The arundo leaf miner Lasioptera donacis (Diptera: Cecidomyiidae) is a biological control agent of the invasive weed, Arundo donax (Poales: Poaceae) which is severely threatening riparian habitats throughout the southern half of the United States, from California to Maryland, and Mexico. The agent, which is native from Mediterranean Europe, was recently permitted for release in the U.S and Mexico. However its pupae, which are preferred for transatlantic shipment, were observed to be infested by a nematode. In order to prevent importation of unpermitted organisms, we needed a sensitive method to detect nematodes or fungi infesting the pupae, and to determine their identification and prevalence. PCR based screening was applied to pupae collected at one site in France using different primer sets. Results showed that pupae were infested by a single nematode species, but no fungal pathogens were observed. This approach would enable reliably screening populations of the agent within the Mediterranean region to collect nematode-free agents. Our study also suggested that the females emerging from pupae are free of fungi, including the purported symbiont Arthrinium arundinis, which implies that they must collect the conidia of this fungus from the environment in order to successfully infest plants.