Non-target organisms on Bt corn hybrids MON89034 and MON89034/NK603 : Part 2. functional guilds of arthropods in regulated field trial sites during dry season in Luzon and Mindanao, Philippines

Issue Date

4-2012

Abstract

A study was conducted in the regulated field trial sites in Isabela (Ilagan), Pangasinan (Sta. Maria) and South Cotabato (Tupi), to determine the effects of two new transgenic corn hybrids on the communities of non-target arthropods (or NTO) specifically the non-target functional guilds classified into predators, parasites/parasitoids, other herbivores or phytophagous arthropods (pests), pollinators and neutrals/vagrants. The guilds were studied among four hybrid treatments in three replicates arranged in a randomized complete block design. Treatments were Bt corn hybrids MON89034 and MON89034/NK603, and conventional hybrid DK818 with and without chemical protection. Arthropods were sampled through net sweeping, net-bagging/vacuum sampling, pitfall trapping, sugar-and protein-baiting, and visual count. Data on guild composition showed that sucking herbivores consistently had higher number of individuals, followed by predators, then by neutrals and vagrants, with parasitoids, pollinators, and chewing herbivores as the fewest across treatments, sites, and corn growth stages, although the differences were not statistically significant. The abundance of parasitoids, although not significantly different across treatments, sites and corn growth stages, was highest in South Cotabato and lowest in Pangasinan. For predators, the Isabela site had he highest abundance with dominant species belonging to Order Araneae (spiders). The lady beetle (Coccinellidae) were the dominant species in Pangasinan and South Cotabato. Results revealed that the new transgenic corn hybrids have enhanced the presence of non-target functional guilds in the three regulated trial sites. Diversity indices showed that the site in Mindanao (South Cotabato) had more diverse arthropod communities than in either site in Luzon (Isabela or Pangasinan). Continuing study for at least two seasons is suggested to fully characterize the impact of the new corn hybrids on NTO communities in the field.

Source or Periodical Title

The Philippine Entomologist

ISSN

0048-3753

Volume

26

Issue

1

Page

28-53

Document Type

Article

Frequency

semi-annually

Physical Description

illustrations ; tables

Language

English

En – AGROVOC descriptors

ARTHROPODA; MAIZE; BACILLUS THURINGIENSIS; HYBRIDS; HYBRIDIZATION; BACTERIAL PESTICIDES; HERBICIDE RESISTANCE; INSECTICIDAL PROPERTIES; PHILIPPINES

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