Assessment of intercropping tomato and sainfoin for the control of Tuta absoluta (Meyrick).
In the present study, the density of tomato leafminer (TLM), Tuta absoluta (Meyrick), the diversity and abundance of its predators and parasitoids, and crop yields were determined in a monoculture of tomato, Lycopersicon esculentum (Mill.), (T), a monoculture of sainfoin, Onobrychis viciifolia Scop., (S) and intercropping tomato and sainfoin in four configurations of rows, namely, one row of tomato and two rows of sainfoin (1T: 2S), two rows tomato and two rows sainfoin (2T: 2S), three rows tomato and two rows sainfoin (3T: 2S), and four rows tomato and two rows sainfoin (4T: 2S). These experiments were conducted on a farm during 2016 and 2017 in Iran. Intercrops caused a significant (P<0.05) reduction in the number of TLM eggs, larvae and galleries and promoted a marked increase in the values of Shannon diversity index (H′) for the species composition of TLM predators. Orius niger (Wolff) and Nesidiocoris tenuis (Reuter) were the dominant TLM predators recorded. Moreover, larval parasitoids Bracon hebetor Say and Neochrysocharis formosus (Westwood) were found to be more abundant relative to the other parasitoids in both 2016 and 2017. The larval parasitism rate was higher in intercrops than in tomato monoculture. On the other hand, the land equivalent ratio (LER) in intercrops was greater than one specifically, in 1T:2S (1.22 in 2016 and 1.17 in 2017) and 2T:2S (1.22 in 2016 and 1.19 in 2017). These findings demonstrated that intercropping tomato with sainfoin particularly, in 1T: 2S and 2T: 2S row ratios were effective in controlling T. absoluta in tomato fields.