Suchergebnisse

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.