Suchergebnisse

A 4-yr on-farm study was conducted in the Philippines between 2006 and 2009 to determine if there are any long-term impacts of Bt corn on the arthropod community on commercial farms and in adjacent riparian areas. Arthropod counts were gathered by visual inspection of corn plants in three pairs of commercial farms and by sweep sampling in riparian sites close by. Sampling showed that species composition between Bt and non-Bt corn and between riparian areas adjacent to Bt or non-Bt corn were similar. Principal response curves and analysis of variance showed that there were no adverse effects of Bt corn on the abundance of natural enemies either in crops or adjacent riparian sites. The frequently observed natural enemies in Bt corn were the predatory coccinellid beetle, Micraspis discolor (F.) and spiders (Araneae). Arthropod diversity was similar 1) in Bt- and non-Bt corn and 2) the adjacent riparian areas. Taken together, the two parts of this study show that Bt corn does not have any long-term adverse effect on arthropod communities in corn (Zea mays L.) or in adjacent riparian ecosystems. The methods and results described in this study will be useful to Philippine government regulators in making recommendations and policy guidelines related to monitoring for environmental effects of transgenic crops. The current study did not attempt to demonstrate the direct exposure of arthropods in riparian sites to transgenic Cry1Ab protein that might come from adjacent Bt corn fields; that would require different experimental methods but the current study suggests such effects are unlikely. © 2012 Entomological Society of America.

Cagayan Valley, which includes Isabela, Cagayan and Nueva Vizcaya, is one of the leading corn producing regions of the country. In 1999 it led the whole country in terms of total corn production. Now, this increase in yield from improved production techniques and the use of Bt corn is gravely threatened by the new corn plant hopper pest, Stenocranus pacificus Kirkaldy. As of last year, this new pest has been monitored in Jones and Echague, Isabela and at Tauo, Cagayan. As of this year, two towns in Nueva Vizcaya and eleven towns in Isabela are invaded. Lessons learned from the 2004 invasion in Mindanao by this pest have been utilized. The BPI thru the Crop Protection Division, the Crop Protection Cluster of UP Los Baños thru the National crop Protection Center (NCPC) and Monsanto Inc. are actively assisting the DA RFU 2 to combat this pest. Surveillance and pest management outreach programs are being extended to local government units.

The Asian corn borer (ACB), Ostrinia furnacalis Guenee, is the major insect pest of corn in the Philippines. It causes yield reduction from 20 to 80%. For this reason, farmer adoption of Bt-corn since its approval for commercial use in 2002 has been increasing. Bt-corn is the latest technology introduced to control the population of the ACB. This technology involves the transfer of a gene from a common soil bacterium, Bacillus thuringiensis (Bt), to a corn plant. The gene produces Cry1Ab protein that is lethal to ACB. About 400,000 hectares of the total corn production area have been planted to Bt-corn. Thus the Philippines is now ranked as #10 among 13 Biotech Mega-countries. Despite the commercial success of Bt crops, there is widespread concern that the advantages provided by the technology will be short-lived because the Bt toxin in plant tissues can lead to the selection and multiplication of rare Bt-resistant ACB survivors. Monitoring the performance of Bt-corn is required to detect the development of ACB resistance at the earliest time possible. The government therefore, mandated formulation of an Insect Resistance Management (IRM) strategy for Bt corn. This study aimed to document the effect of Cry1Ab protein on the ACB. The ACB females were collected in Lubao, Pampanga from May 2006 to the present. Collected insects from the field were reared in the laboratory using an ACB artificial diet. The F1 generations of ACB were sib-mated to produce the F2 generations in the bioassay test for the Cry1Ab protein. A total of twenty two thousand four hundred eighty five (22,485) neonates or newly hatched larvae from five hundred (500) female lines were individually assayed using surface contamination technique with a discriminating dose of Cry1Ab (LC99=120 ng/cm2, Alcantara, unpubl.). An equal number of larvae served as control check using 0.1M carbonate buffer. Mortality rate for all of the lines is at its peak during the first seven days of exposure to the toxin. Around 800 gravid females are expected to be collected, reared, and progenies tested at the end of the project.