Foi avaliado o efeito da temperatura e da umidade relativa na biologia de Trichogramma, um parasitoide de ovos, no hospedeiro natural, a broca-da-cana e a capacidade de parasitismo e sobrevivência no hospedeiro alternativo a traça-do-arroz. Estudou-se a preferencia hospedeira do parasitoide, comparando-se broca-da-cana, traça-do-arroz e traça-da-farinha. Estudou-se o efeito do fotoperíodo no parasitismo sobre a traça-da-farinha. Houve uma relação inversa entre a duração do ciclo do parasitoide, criado em ovos da broca e o aumento de temperatura na faixa de 18 a 32ºC havendo maior mortalidade do parasitoide a 18ºC. A temperatura afetou a razão sexual do parasitoide, com maior numero de machos a 32ºC. O parasitoide apresentou maior longevidade nas temperaturas mais baixas, vivendo mais na traça-do-arroz do que na broca, para cada geração da broca poderão ocorrer 4,8 gerações do parasitoide. A umidade relativa mais adequada para criar em ovos da broca situou-se entre 90 e 100% o parasitismo foi maior em presença de luz. A traça-do-arroz e a traça-da-farinha foram hospedeiros alternativos adequados para a multiplicação do parasitoide

The present work was carried out in arder to evaluate the temperature and relative humidity effects onthe biology of Trichogramma galloi, Zucchi 1988 on its natural host, Diatraea saccharalis (Fabricius, 1794) as well as the parasitism and survival capacity on its factitious host, Corcyra cephalonica (Staintan, 1865). Meanwhile, the host preference of the parasitoid was analyzed by comparing D. saccharalis, Anagasta kuehniella (Zeller, 1879) and C. cephalonica. The study of the biotic and abiotic factors, including the photoperiod effect on the A. kuehniella parasitism, may provide the required information to enable the use of T. galloi in inundative realeases in the sugar cane moth borer. The research was conducted in the Laboratory of Biology, of the Department of Entomology, Escola Superior de Agricultura “Luiz de Queiroz”, University of São Paulo, campus of Piracicaba. An inverse relationship was observed between the period of time of the T. galloi cycle when reared on D. saccharalis eggs and the temperature increase ranging from 18 to 32°C, with a higher mortality rate of the parasitoid at 18°C. The temperature affected the sexual rate of T. galloi, with a higher number of males at 32°C. The parasitoid presented higher longevity at lower temperatures and lived longer on C. cephalonica than on D. saccharalis eggs. For each D. saccharalis generation there may occur 4.8 T. galloi generations. The most appropriate temperature for T. galloi parasitization varied according to the host, either natural (D. saccharalis) or factitious (C. cephalonica). The most appropriate relative humidity for rearing T. galloi on D. saccharalis eggs r-anged from 90 to 100%. The survival curve of T. galloi females on either natural or factitious host followed weibull's distribution. At the same thermal condition the T. galloi parasitism was higher on the natural host. The T. galloi parasitism was higher on the natural host. The T. galloi parasitism on A. kuehniella eggs was more intense when exposed to light. Both C. cephalonica and A. kuehniella were suitable factitious hosts for the T. galloi multiplication