Résumé
Whiteflies and whitefly-transmitted viruses are some of the major
constraints on European tomato production. The main objectives of
this study were to: identify where and why whiteflies are a major limitation
on tomato crops; collect information about whiteflies and associated
viruses; determine the available management tools; and identify
key knowledge gaps and research priorities. This study was conducted
within the framework of ENDURE (European Network for Durable
Exploitation of Crop Protection Strategies).
Two whitefly species are the main pests of tomato in Europe: Bemisia
tabaci and Trialeurodes vaporariorum. Trialeurodes vaporariorum
is widespread to all areas where greenhouse industry is present, and
B. tabaci has invaded, since the early 1990’s, all the subtropical and
tropical areas. Biotypes B and Q of B. tabaci are widespread and especially
problematic. Other key tomato pests are Aculops lycopersici,
Helicoverpa armigera, Frankliniella occidentalis, and leaf miners. Tomato
crops are particularly susceptible to viruses causingTomato yellow
leaf curl disease (TYLCD). High incidences of this disease are
associated to high pressure of its vector, B. tabaci. The ranked importance
of B. tabaci established in this study correlates with the levels
of insecticide use, showing B. tabaci as one of the principal drivers
behind chemical control. Confirmed cases of resistance to almost all
insecticides have been reported. Integrated Pest Management based
on biological control (IPM-BC) is applied in all the surveyed regions
and identified as the strategy using fewer insecticides. Other IPM
components include greenhouse netting and TYLCD-tolerant tomato
cultivars. Sampling techniques differ between regions, where decisions
are generally based upon whitefly densities and do not relate
to control strategies or growing cycles. For population monitoring and
control, whitefly species are always identified.
In Europe IPM-BC is the recommended strategy for a sustainable
tomato production. The IPM-BC approach is mainly based on inoculative
releases of the parasitoids Eretmocerus mundus and Encarsia formosa and/or the polyphagous predators Macrolophus caliginosus
and Nesidiocoris tenuis. However, some limitations for a wider implementation
have been identified: lack of biological solutions for some
pests, costs of beneficials, low farmer confidence, costs of technical
advice, and low pest injury thresholds. Research priorities to promote
and improve IPM-BC are proposed on the following domains: (i) emergence
and invasion of new whitefly-transmitted viruses; (ii) relevance
of B. tabaci biotypes regarding insecticide resistance; (iii) biochemistry
and genetics of plant resistance; (iv) economic thresholds and sampling
techniques of whiteflies for decision making; and (v) conservation
and management of native whitefly natural enemies and improvement
of biological control of other tomato pests.