Effect of temperature and relative humidity on longevity and development of the parasitoid, Tetrastichus pyrillae Crawford (Hymenoptera: Eulophidae)

Abstract

Combined effects of constant temperature (15–35°C) and relative humidity (50–90%) on longevity and total duration of life cycle of Tetrastichus pyrillae Crawford, one of the most common egg parasitoids of the sugar-cane leaf hopper, Pyrilla perpusilla Walker were determined and are discussed. Influence of the temperature both on the longevity and the developmental duration of this egg parasitoid was highly significant while the relative humidity did not produce any marked change. Average longevity of males decreased from 5.89 to 1.06 days and that of females from 9.60 to 1.04 days in response to corresponding rise in test temperature from 15 to 35 ± 1.5°C. Mean duration of its life cycle also declined from 40.5 to 9.8 days as the rearing temperature was raised from 15 to 30 ± 1.5°C. Developing parasitoid died, without attaining adulthood within its host eggs, at or above 32.5°C.

Résumé

Les effets combines d'une temperature constante (15–35°C) et d'une humidité relative (50–90%) sur la longevite et la duree totale du cycle de vie du Tetrastichus pyrillae Crawford, undes plus communs parasites de l'oenf du Pyrilla perpusilla Walker, furent determines et studies. L'influence de la temperature a la fois sur la longevite et la duree de developpement du parasite de l'oeuf est tres importante, alors que l'humidite relative l'influe pour ainsi dire pas. La longevite moyenne des maies montrait une décroissance de 5,89 a 1,06 jours et celle des femelles de 9,60 a 1,04 jours a mesure que la temperature augmentait de 15 a 35 ± 1,5°C. La durée moyenne du cycle de vie décroissait de 40,5 a 9,8 jours quand la temperature de culture etait augmentes de 15 a 30 ± 1,5°C. Les parasites en train de se developper, meurent, sans parvenir a l'age adulte, dans l'oeuf qu'ils parasitent, a la temperature de 32,5°C et au-dessus.