Pest categorisation of tomato leaf curl New Delhi virus

Abstract

Following a request from the European Commission, the Panel on Plant Health performed a pest categorisation on tomato leaf curl New Delhi virus (ToLCNDV). ToLCNDV is a well‐defined bipartite Begomovirus species, sometimes associated with satellite molecules. It is transmitted by Bemisia tabaci to a wide range of hosts. ToLCNDV is reported from Estonia, Greece, Italy, Portugal and Spain, with limited distribution. The prevalent strain (ToLCNDV‐ES) in these countries is particularly adapted to cucurbits and is different from isolates reported outside the EU, which are better adapted to solanaceous crops and could therefore pose additional risk for EU agriculture. The virus is regulated under Commission Implementing Regulation (EU) 2019/2072. The main pathway of entry identified is plants for planting of susceptible hosts, even if entry could also occur via commodities carrying viruliferous B. tabaci and possibly by seeds. While establishment and local spread rely on B. tabaci, the virus can also be dispersed over long distances by movement of infected plants for planting. Establishment and spread are limited to regions with ecoclimatic conditions suitable for the establishment of vector populations (southern regions of Europe) or can occur as outbreaks wherever crops are grown under protected cultivation. The main uncertainties associated with this pest categorisation are the distribution and prevalence of ToLCNDV in the EU, the magnitude of the virus impact particularly on hosts different from Cucurbitaceae, and seed transmission. ToLCNDV meets all the criteria evaluated by EFSA to qualify as potential Union Quarantine Pest (QP); conversely, ToLCNDV does not meet the criterion of being widespread in the EU to qualify as a Regulated Non‐Quarantine Pest (RNQP). Should new data show that ToLCNDV is widespread in the EU, the possibility would exist for non‐EU isolates to qualify as QP, while ToLCNDV EU isolates (ToLCNDV‐ES) could qualify as RNQP.

RETRACTED: Emergence of Asian endemic begomoviruses as a pandemic threat

“…ToLCNDV was then found to infect zucchini crops in Greece in 2018 ( Orfanidou et al, 2019 ), adding to its geographical diversity. Later, ToLCNDV expanded to Tunisia, Italy, Morocco, and Greece ( Panno et al, 2016 ; EFSA Panel on Plant Health et al, 2020 ). Furthermore, ToLCNDV has recently been identified in cucurbit plants in Portugal and Estonia and in members of the Solanaceae family in Italy, indicating that it is rapidly spreading throughout Europe ( Parrella et al, 2018 , 2020 ).…”

A new challenge in melon resistance breeding: the ToLCNDV case

“…Removing plants that are infected with the virus quickly or to remove plant remainders and other plant hosts around the area that whiteflies can use as shelters could also be helpful to reduce epidemics. An integrated pest management strategy suggested monitoring of insect populations and planning of the cultivation periods outside of flight activity periods of B. tabaci (Bragard et al 2020). Eventually, large efforts are carried out by the plant breeding industry for introducing tolerant or resistant cucurbit varieties that could be widely adopted to limit the economic loss due to ToLCNDV in Europe.…”

“…ToLCNDV is a whitefly transmitted bipartite Geminivirus. It's highly flexible genomic organization is thought to be a contributing factor to its wide distribution in hosts (43 dicotyledonous species so far) and areas around the world (Pakistan, India, Bangladesh, Iran, Sri Lanka, Malaysia, Taiwan, Thailand, Indonesia, Tunisia, Spain, Italy, Morocco, Algeria, Portugal, Estonia, Greece) (Zaidi et al 2017;Bragard et al 2020). The virus belongs to Geminiviridae (genus: Begomovirus) a family of circular single stranded DNA viruses and has two genome components DNA-A and DNA-B.…”

Pest survey card on tomato leaf curl New Delhi virus

“…To discriminate virus species, complete DNA-A genome sequences are considered and distinct virus species have <90% pairwise nucleotide sequence identities with other members of the genus (Brown et al, 2015). Most ToLCNDV DNA-A sequences have more than 90% sequence identity (EFSA PLH Panel, 2020) and despite uncertainties about the ambiguous status of a few virus isolates with diverging genome sequences, ToLCNDV is a well-established virus species with a clear taxonomic status.…”

“…The information presented in this pest survey card was summarised from various scientific publications and other documents, including the EFSA pest categorisation of tomato leaf curl New Delhi virus (EFSA PLH Panel, 2020), and the EFSA risk assessment on Bemisia tabaci and the viruses it transmits (EFSA PLH Panel, 2013).…”