Capacidade de parasitismo de Trichogramma exiguum Pinto & Platner, 1978 (Hymenoptera: Trichogrammatidae) em ovos de Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) em diferentes temperaturas / Parasitism capacity of Trichogramma exiguum Pinto & Platner, 1978 (Hymenoptera: Trichogrammatidae) on different temperatures on Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) eggs

RESUMO

Estudou-se a capacidade de parasitismo de Trichogramma exiguum Pinto & Platner, 1978 (Hymenoptera Trichogrammatidae) em ovos de Plutella xylostella (L., 1758) (Lepidoptera Plutellidae) nas temperaturas de 18, 20, 22, 25, 28, 30 e 32°C, avaliando-se o número de ovos parasitados diariamente, a porcentagem acumulada de parasitismo, o número total de ovos parasitados por fêmea e a longevidade de fêmeas. O ritmo de parasitismo, durante as primeiras 24 horas, oscilou de 1,5 a 11,7 ovos parasitados por fêmeas de T. exiguum, nas temperaturas entre 18 e 32°C. O parasitismo acumulado de ovos de P. xylostella, nas temperaturas de 18, 20, 22, 25, 28, 30 e 32°C, atingiu 80 por cento, respectivamente, aos 10, 7, 8, 5, 5, 4 e 5 dias, por T. exiguum. As maiores taxas de parasitismo obtidas por T. exiguum ocorreram nas faixas térmicas de 25, 30 e 32°C. A longevidade de fêmeas de T. exiguum, nas faixas térmicas compreendidas entre 18 e 32°C, variou de 4,2 a 7,4 dias.

ABSTRACT

The parasitism capacity of Trichogramma exiguum Pinto & Platner, 1978 (Hymenoptera Trichogrammatidae) on eggs of Plutella xylostella (L., 1758) (Lepidoptera Plutellidae) was studied, under temperatures of 18, 20, 22, 25, 28, 30 and 32°C aiming at evaluating the number of days with parasitism, cumulated parasitism, total number of eggs parasited per female and their longevity. Parasitism during the first 24 hours ranged from 1.5 to 11.7 eggs of P. xylostella per T. exiguum female in the range of 18 to 32°C. Cumulated egg parasitism of P. xylostella by T. exiguum reached 80 percent after 10, 7, 8, 5, 5, 4 and 5 days at 18, 20, 22, 25, 28, 30 and 32°C. Higher parasitism rates were recorded at 25, 30 and 32°C while longevity of T. exiguum females varied from 4.2 to 7.4 days under temperatures of 18 to 32°C.