Resposta funcional de Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) parasitando ovos de Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae): efeito da idade do hospedeiro

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 [？ = 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.