Hosts and distribution of ToCV and TICV
Find details of the range of different hosts, and the geographical areas of distribution, common to each virus.
Although the tomato Solanum lycopersicum is the only host where infection is thought to be of major importance, both viruses have quite a wide host range.
TICV has been reported to infect 19 species, from 4 botanical families including the Solanaceae (9 species), the Asteraceae (7 species), Amaranthaceae (2 species), and Ranunculaceae (1 species).
Other crops affected
The virus has also been reported to infect other commodity crops including sweet pepper (Capsicum annum), lettuce (Lactuca sativa) and globe artichoke (Cynara scolymus), as well as ornamental species such as Petunia hybrids and Zinnia.
However, the vast proportion of hosts of this virus are classified as wild or weed species (47%), including common UK field weeds such as fat-hen (Chenopodium album) and black nightshade (Solanum nigrum).
ToCV is known to affect 34 species from 12 botanical families.
The majority of these are from the Solanaceae (13 species), the Asteraceae (5 species) and the Fabaceae (3 species).
Again, the majority of recognised host species are classified as weeds (67%), including common UK field weeds such as fat-hen (Chenopodium album), common chickweed (Stellaria media), greater plantain (Plantago major), and black nightshade (Solanum nigrum).
The virus has been recorded from several commodity crops, including sweet pepper (C. annum) and aubergine (Solanum melongena).
However, unlike its counterpart, ToCV has been recorded from potato (S. tuberosum), although this record is from Brazil.
With a broad range of potential hosts, should an outbreak occur outside a glasshouse environment, there is potential for the virus to be harboured and spread among the wild plant species if the whitefly were to persist for long enough periods.
Transmission of TICV and ToCV is exclusively by whiteflies in the genera Trialeurodes and Bemisia.
These virus vectors are pests naturally found affecting crops in tropical and subtropical regions.
The general distribution of these viruses, therefore, reflects the distribution of their vectors.
Outbreaks in glasshouses
In cooler temperate regions, glasshouse growing conditions can prove to be favourable for the introduced pests and there have been sporadic outbreaks recorded in Northern Europe as a result of infected plants, and vectors, entering glasshouses.
Since their discovery/confirmation in the USA in the 1990s, both TICV and ToCV have spread across the world into major areas of tomato production.
Tomato infectious chlorosis virus has a relatively narrow range of global distribution.
It has been reported on both the East and West coast of the USA, Mexico, Japan, Indonesia, Taiwan, and from several countries around Europe and the Mediterranean Basin, including Italy, Greece, Bulgaria, France, Jordan and Tunisia.
By contrast, Tomato chlorosis virus has a much broader distribution, possibly a reflection of the broader geographic range of the vectors that can transmit the virus.
It has been recorded across all major tomato-growing regions, with the exception of Australia.
It has also been recorded across the USA, central and south America, East Asia and the Middle East, as well as North, sub-Saharan and South Africa.
In Europe and the Mediterranean Basin, the virus has been widely reported as being present within glasshouse environments and also with a presence in field-grown tomatoes in Southern Europe where whitefly populations occur naturally in higher numbers during the summer months.
In 2017, ToCV was detected in the Netherlands for the very first time in the glasshouses of three fruit-production companies.
The content for this web page was originally authored for AHDB by Adrian Fox and Adam Buxton-Kirk (Fera Science Ltd).