The functional response of Trichogramma pretiosum Riley parasitizing Tuta absoluta (Meyrick) eggs on industrial var. IPA-5 tomato leaves was studied for individual females at 12-36, 36-60 and > 60 h old eggs during one day exposition time. The handling time (Th = 0.77 h) and attack rate (a' = 0.80 h-1) were obtained from the linearization of parasitism by means of Woolf's equation. Based on these results, the functional response fitted the Type II: Na = Nt [1 - exp (-0,80 / (1 + 0,0258Nt))], but only when eggs were 12-36 h old. The estimated maximum number of parasitized eggs was 31.1, while the maximum observed number was 30, at the egg density of 60. The Th was 3.22% of the total exposure time. The increase in parasitism was up to 55 eggs/leaflet density, showing a Type I functional response for lower egg densities [ÿ = 4.53 + 0.288 (± 0.054)x], while in higher densities the parasitism was stable and similar to that achieved at the 56-80 and 81-100 eggs/leaflet densities (mean ± SD = 20.1 ± 4.01 eggs). Increase in host density was not followed by increase in parasitism for eggs 36-60 h old and older than 60 h.
Insecta; tomato leafminer; biological control; egg parasitoid; parasitism rate
