Development and thermal requirements of Trichogramma pretiosum Riley, rearing in two tomato leafminer

The biology of Trichogramma pretiosum in eggs of Phthorimaea operculella (Z eller) and of Tuta absoluta (Meyrick) were studied under different temperat ures (18, 20, 22, 25, 30, 32 degrees C), 70 +/- 10% RU and photophase of 14 hours, with the aim of determining the thermal requirements and the number of generations during the year. There was an inverse correlation between t he duration of the cycle and the increase of temperature in the thermal zon e studied. Nevertheless, the sexual ratio was not affected by the temperatu re when the host was T. absoluta. The viability of T. pretiosum, reared in I! operculella, was more affected than in T. absoluta. The thermal requirem ent, calculated by the hyperbole was higher for T. absoluta (131.3 degrees day) in relation to P. operculella (120.9 degrees day), and the thermal thr eshold was lesser respectively, 12.98 degrees C and 13.53 degrees C. For bo th species of leafminer, the longevity of parasitoid always obeyed the Weib ull's distribution. The increase of the potential was estimated for both sp ecies of leafminer, according to the number of annual generations.