Examples of direct damage of Frankliniella occidentalis to outdoor crops in Europe
Frankliniella occidentalis (EPPO A2 quarantine pest) is a very polyphagous pest which transmits viruses (e.g. tomato spotted wilt tospovirus) and causes direct damage to crops. In Europe, it is generally found on glasshouse vegetables and ornamentals but in southern countries direct damage and losses are also reported on several outdoor crops such as strawberries, melons, tomatoes, aubergines, pepper and fruit crops. Some examples of direct damage are given below.
Table grapes
In Italy, it is reported that since 1989-90, F. occidentalis is the second most important pest (after Lobesia botrana) of table grapes (Moleas et al., 1996), particularly in Puglia and Sicilia. Damage is caused by oviposition at flowering which then causes lesions on the berries. This type of damage is also observed in France, notably on white cultivars grown under protected conditions (Grasselly, 1996).
Peaches, nectarines and apricots
In southern France particularly in Roussillon (Grasselly, 1986), damage on peach has been reported since 1988. Peach is the most severely attacked stone-fruit crop. Feeding damage is caused to the epidermis of peaches and nectarines ('silvering'), usually just before harvest. This type of damage is also oberved in Italy (Guarino ; Tocci, 1995). In hot regions of Spain (e.g. in the Valle del Guadalquivir) severe losses have been observed on nectarines (Gonzàlez et al., 1994). As the thrips can also attack trees during flowering, flower abortion, fruit deformation and discoloration (russeting) are observed (in addition to silvering which is observed when nearly mature fruit are infested). In Israel, F. occidentalis is reported as seriously retarding the vegetative growth of apricot trees of most cultivars in all growing areas, especially in nurseries (Klein et al., 1995). Larvae feed within the apical buds which cause abnormal leaves, and loss of apical dominance. New branches have shortened internodes and infested buds may die early in the summer. No damage on apricot fruit was observed.
Apples
In southern France (Grasselly, 1986), damage is occasionally reported on apples, essentially on the cultivar Granny Smith. Damage is caused by oviposition on the young fruit which induces necrotic spots surrounded by a white halo.
Sunflower
Severe damage on commercial sunflower crops (Helianthus annuus) was reported in 1992-93 in Israel (Chyzik et al., 1995). Adults of F. occidentalis appeared at the beginning of flowering and population decreased towards completion of anthesis, and they damaged kernels.
Sources
Gonzàles, E.; Alvarado, M.; Berlanga, E.; Serrano, A.; de la Rosa, A. (1994) Damage to nectarines caused by thrips in the Guadalquivir Valley.
Boletin de Sanidad Vegetal, Plagas, 20(1), 229-241.
Grasselly, D. (1996) Le thrips Frankliniella occidentalis en cultures légumières et fruitières. Description des dégâts directs.
Phytoma - La Défense des Végétaux, no. 482, 42-43.
Guarino, F.; Tocci, A. (1995) Frankliniella occidentalis on peach and nectarine in Calabria (south Italy).
Bulletin OILB-SROP, 18(2), 21-23.
Klein, M.; Chyzik, R.; Ben-Dov, Y.; (1995) The western flower thrips Frankliniella occidentalis damages the vegetative growth of apricot trees in Israel.
Alon Hanotea, 49(12), 540-544.
Moleas, T.; Baldacchino, F.; Addante, R. (1996) Integrated control of Frankliniella occidentalis (Pergande) on table grapes in 1992-94.
Difesa delle Piante, 19(1), 41-48.