Influence of Bt-corn variety Yieldgard® on the effectiveness of Trichogramma evanescens (Hymenoptera: Trichogrammatidae), an egg parasitoid of the Asian corn borer, Ostrinia furnacalis (Guenne)

Issue Date

10-2004

Abstract

The study was conducted in Isabela State University during the dry season and in the farmer's fields in Barangay Sinabbaran, Echague, Isabela and Barangay Villaluna, Cauayan, Isabela during the wet season cropping. Significantly more Asian corn borer (ACB) egg masses were recorded on Bt-corn Yieldgard® than on its Isohybrid during teh dry season cropping. Although no Trichogramma parasitoids were released in the field, egg mass parasitism ranged from 35 to 50% at 30 days after planting (DAP), and increased to 100% at 59 DAP in both the Yieldgard and Isohybrid varieties. The populations of flower bug (Orius tantillus), coccinellid beetle, and spiders were also higher on Yieldgard than on the Isohybrid. No ACB damage was recorded on Yieldgard. In spite of the very high egg mass population recorded, the Isohybrid was almost totally free from ACB damage prior to harvesting due to high natural enemy population. As a result, yield of Yieldgard did not differ significantly from that of the Isohybrid. Low rate of trichogramma parasitism was recorded in the two Barangays in Isabela during the wet season cropping. Likewise, the predator population (Orius, coccinellid beetles and spiders) was negligible. Although fewer egg masses were recorded during the wets season cropping, ACB damage was significantly higher on the Isohybrid variety. Consequently, significantly higher yield was recorded for Yieldgard, in both locations, with more than 5 tons yield advantage over the Isohybrid. The very high Trichogramma parasitism and high predator population on variety Yieldgard during the dry season cropping suggested that Bt-corn is not deleterious to the natural enemies. These natural enemies could help in delaying ACB resistance development in Bt-corn by controlling the pest at the egg and early larval stages to reduce emerging Bt-resistant adults.

Source or Periodical Title

Philippine Entomologist

ISSN

0048-3753

Volume

18

Issue

2

Page

163

Document Type

Article

Frequency

semi-annually

Language

English

En – AGROVOC descriptors

OSTRINIA FURNACALIS; TRICHOGRAMMA; BACILLUS THURINGIENSIS; PARASITOIDS; CROPPING SYSTEMS

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