NON-TARGET ORGANISMS ON Bt CORN HYBRIDS MON89034 AND MON89034/NK603: PART 3. FUNCTIONAL GUILDS OF ARTHROPODS IN REGULATED FIELD TRIAL SITES DURING THE WET SEASON IN LUZON AND MINDANAO, PHILIPPINES

Ireneo Jr. L. Lit, Merdelyn T. Caasi-Lit, Kristine O. Abenis, Nolan Antoni Q. Manalo, Ariel R. Larona, Orlando L. Eusebio, Edwin A. Benigno

Abstract


Regulated field experiments were conducted in Ilagan, Isabela and Tupi, South Cotabato to assess the effects of two new Bt corn hybrids (MON89034 expressing two insecticidal proteins, Cry1A.105 and Cry2Ab2 and MON89034/NK603 that additionally expresses glyphosate resistance) on non-target organisms (NTOs) specifically arthropods. Effects were assessed in comparison with two non-Bt corn hybrids (DK818 isogenic conventional corn and NK603 with glyphosate resistance trait) with no chemical protection. Arthropods were sampled using sweep net and vacuum, pitfall trapping, sugar- and protein-baiting and visual counting. A total of 15,970 and 31,699 individuals were collected in Isabela and South Cotabato, respectively. These arthropods are spread in 18 insect orders with 113 families for Isabela and 20 insect orders with 127 families for South Cotabato. The functional guilds (predators, parasitoids, pollinators, neutrals, non-target corn herbivores and target pests) appeared unhampered by the corn type as to their respective roles in the corn agroecosystem. The overall trend indicates that the mean number of arthropods was highest at the reproductive stage of the corn plant. The addition of NK603 in the wet season trial had no effect on the arthropod populations. In summary, the combined analysis showed that the arthropod populations were not significantly different among treatments and the levels of arthropod populations in non-Bt and Bt-corn fields did not show any significant difference. Data generated from both dry and wet season trials support the hypothesis that MON89034 and MON89034/NK603 have no effects on non-target arthropods in the corn ecosystem and suggest that there are no significant seasonal variations in the effects of Bt corn hybrids on NTOs.

Key words: abundance, Asian corn borer, Bt corn hybrids, diversity, functional guilds, MON89034, MON89034/NK603, NK603, non-target organisms, Ostrinia furnacalis


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