D. Pratissoli et Jrp. Parra, Development and thermal requirements of Trichogramma pretiosum Riley, rearing in two tomato leafminer, PESQ AGROP, 35(7), 2000, pp. 1281-1288
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.