Trophic web associated with the South American tomato moth Tuta absoluta: implications for its conservation biological control in Argentina

The South American tomato moth Tuta absoluta is a major pest targeted for biological control by entomophagous insects. Trophic interactions among parasitoids of T. absoluta and other gelechiids feeding on crop and spontaneous wild solanaceous were investigated in north-eastern Buenos Aires (Argentina), with the aim of assisting in the design of conservation biological control strategies. A quantitative parasitoid trophic web was constructed that included five gelechiid leafminers, five solanaceous species and a complex of 18 parasitoid species. The relative abundance of T. absoluta was highest in the Solanum melongena crop, followed by the wild plants Nicotiana glauca, Solanum americanum, Solanum sisymbriifolium and Salpichroa origanifolia. Greater parasitoid species richness associated with T. absoluta was found in the wild plants N. glauca and S. americanum. Pseudapanteles dignus was the main parasitoid of T. absoluta and co-occurred with this pest in four plant species. Parasitism of T. absoluta by P. dignus was observed throughout the year in S. melongena, reaching values up to 33%, whereas it was sporadic and exhibited lower parasitism rates in the noncrop S. sisymbriifolium, N. glauca and S. americanum. The presence of some wild solanaceous plants should be promoted to maintain the T. absoluta– P. dignus interaction in horticultural farms.