Empoasca fabalis DeLong (Hemiptera: Cicadellidae) in European sweet potatoes: records, leaf damage, and Auchenorrhyncha insights

Authors: AGUIN-POMBO, DORA - Universidade De Madeira; BOAVIDA, CONCEICAO - Instituto Nacional De Investigação Agrária E Veterinária; VALDIVIESSO, TERESA - Instituto Nacional De Investigação Agrária E Veterinária; TRINDADE, CANDIDA - Instituto Nacional De Investigação Agrária E Veterinária; Backus, Elaine; MATEUS, CELIA - Instituto Nacional De Investigação Agrária E Veterinária

Submitted to: Phytoparasitica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2024
Publication Date: 7/31/2024
Citation: Aguin-Pombo, D., Boavida, C., Valdiviesso, T., Trindade, C., Backus, E.A., Mateus, C. 2024. Empoasca fabalis DeLong (Hemiptera: Cicadellidae) in European sweet potatoes: records, leaf damage, and Auchenorrhyncha insights. Phytoparasitica. 52. Article 66. https://doi.org/10.1007/s12600-024-01176-0.
DOI: https://doi.org/10.1007/s12600-024-01176-0

Interpretive Summary: There are over 1300 Empoasca and related species of leafhoppers, many of which are serious pests on economically important crops worldwide. All are small, inconspicuous, green leafhoppers that are best distinguished by their male reproductive structures. Empoasca fabalis has a widespread distribution across its native American continents, ranging from the southern United States to South America. Recent expansion has extended its range to Hawaii. This paper documents the first arrival of E. fabalis into Europe, in the Canary Islands and Madeira Island, off the coast of southern Portugal. In both North and South America, E. fabalis is a pest on sweet potato. The cultivation of sweet potato has gained significant prominence in Europe, especially in southern countries like Portugal, Spain, Italy, France, and Greece. In mainland Portugal, about 80% of the mainland's output of sweet potato is concentrated in the southern region. The objective of this work was to report the occurrence of E. fabalis on the European mainland, analyse the damage it inflicts on sweet potato leaves via histological examination of internal leaf anatomy, and document the associations of related leafhopper species with sweet potatoes in Europe. Results showed that feeding damage from E. fabalis consisted of numerous, whitish tan spots on the leaves, known as “stipples.” Histological examination showed intact cell walls but partial to complete removal of cell contents, especially in palisade mesophyll cells. The extensive stippling and cellular disruption can limit effective photosynthesis, potentially impacting overall growth and health. Under high population pressures, stippling can lead to whole-leaf destruction, with significant yield reduction if damage occurs early in the season. This work contributes to the understanding of these insect-crop interactions, providing insights into potential implications for agricultural management in Portugal, and aid in understanding this lesser-studied group of leafhoppers in the Iberian Peninsula.

Technical Abstract: The recent surge in sweet potato (Ipomoea batatas) cultivation in Europe prompted an investigation into associated entomofauna within Portugal's southwestern region, known for its longstanding sweet potato production. This study aimed to assess entomofauna associated with this culture. Insect sampling was conducted by sweeping net across three regional sites during 2018 and 2019 revealing the first report of Empoasca fabalis, on the European mainland. Histological examination of sweet potato leaves affected by E. fabalis feeding unveiled significant damage, including the emergence of whitish spots (termed “stipples”) and consequent necrotic spots. Comparative analysis between infested and undamaged control leaves revealed significant damage, involving mesophyll cell content deprivation and cellular disruption. This study describes, for the first time, the histological nature of the necrotic damage and suggests that E. fabalis primarily acts as a stippler on sweet potatoes, mainly targeting mesophyll cells with limited consumption of vascular tissue. The invasive behaviour and wide host range of E. fabalis poses a new threat to sweet potato cultivation. These findings emphasize the urgent need for monitoring to address the potential impact of E. fabalis on Europe’s agricultural ecosystem and native vegetation. Additionally, this survey identified six additional Auchenorrhyncha species, including crucial vectors of plant diseases: Laodelphax striatellus, Psammotettix alienus, Anaceratagallia laevis, Austroagallia sinuata, Empoasca solani and E. alsiosa. This work contributes to the understanding of these insect-crop interactions, providing insights into potential implications for agricultural management in Portugal, and aid in understanding this lesser-studied group in the Iberian Peninsula. These results underline the importance of managing these insects in sweet potato cultivation.