Natural Parasitism of Noctuid Eggs (Lepidoptera) at Different Altitudes of the Central Highlands of Eciador, with Speciel Emphasis on Corn

Abstract

The study aimed at knowing the egg parasitoids of Noctuidae and the decisive factors for the level of parasitism in a mountain ecosystem. In six places of the central highlands of Ecuador, between 2400 and 3030 meters above sea level, noctuid eggs were collected every two weeks from corn fields in order to determine their parasitation. The egg parasitoids found were: Trichogramma preriosum RILEY and T. fasciatum PERK. (Trichogrammatidae), Telenomus sp. (Scelionidae) and Encarsia porteri MERCET (Aphelinidae). Mean parasitism was 26,1 %. There was a very close negative relation between altitude and egg parasitation. Parasitism decreases from 41,5 % at 2400 m to 13,3 %  at 3030 m. The decisive factors seem to be mean temperature and the presence of irrigation facilities. Irrigation helps to stabilize vegetation throughout the year, and thus stabilizes the presence of hosts for the parasitoids.