Natural enemies of lemna minuta in its native range and their potential as biological control agents for Europe

Authors: FLAMINIA, MARIANI - Biotechnology And Biological Control Agency; Pratt, Paul; MASSIMO, CRISTAFARO - Biotechnology And Biological Control Agency; SIMONA, CESCHIN - University Of Roma; ILGOO, KANG - Kyungpook National University; RODRIGO, DIAZ - Louisiana State University

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2024
Publication Date: 8/22/2024
Citation: Flaminia, M., Pratt, P.D., Massimo, C., Simona, C., Ilgoo, K., Rodrigo, D. 2024. Natural enemies of lemna minuta in its native range and their potential as biological control agents for Europe. Biological Control. https://doi.org/10.1080/09583157.2024.2393383.
DOI: https://doi.org/10.1080/09583157.2024.2393383

Interpretive Summary: Lemna minuta, an invasive alien plant originating from North America, poses significant threats to freshwater ecosystems in Europe, causing profound alterations to abiotic and biotic conditions. To explore potential biological control options, surveys for herbivorous arthropods were conducted in two regions of the United States, revealing three candidate species. Subsequent laboratory investigations focused on the weevil Tanysphyrus lemnae and the fly Lemnaphila scotlandae as the most promising agents. Herbivory assessments demonstrated that feeding by both T. lemnae and L. scotlandae negatively affects the viability of L. minuta plants. To evaluate the host specificity of these two potential agents, insects were exposed to five species of duckweeds commonly occurring in North America and Italy. Preliminary host-range testing indicated that T. lemnae develops on all evaluated duckweed species, including those from different genera (Spirodela, Landoltia). Conversely, data revealed that feeding and development of the dipteran L. scotlandae are limited to species in the genus Lemna, but this includes L. minor, a native European species highly threatened in Europe due to competition with L. minuta. No-choice and choice tests confirmed that neither larvae nor adults of L. scotlandae discriminate between the two Lemna species. We conclude that the broad host-range of L. scotlandae renders it unsuitable as a biological control agent of L. minuta in Europe.

Technical Abstract: Lemna minuta, an invasive alien plant originating from North America, poses significant threats to freshwater ecosystems in Europe, causing profound alterations to abiotic and biotic conditions. To explore potential biological control options, surveys for herbivorous arthropods were conducted in two regions of the United States, revealing three candidate species. Subsequent laboratory investigations focused on the weevil Tanysphyrus lemnae and the fly Lemnaphila scotlandae as the most promising agents. Herbivory assessments demonstrated that feeding by both T. lemnae and L. scotlandae negatively affects the viability of L. minuta plants. To evaluate the host specificity of these two potential agents, insects were exposed to five species of duckweeds commonly occurring in North America and Italy. Preliminary host-range testing indicated that T. lemnae develops on all evaluated duckweed species, including those from different genera (Spirodela, Landoltia). Conversely, data revealed that feeding and development of the dipteran L. scotlandae are limited to species in the genus Lemna, but this includes L. minor, a native European species highly threatened in Europe due to competition with L. minuta. No-choice and choice tests confirmed that neither larvae nor adults of L. scotlandae discriminate between the two Lemna species. We conclude that the broad host-range of L. scotlandae renders it unsuitable as a biological control agent of L. minuta in Europe.