Author : Somnuk Wongtong

Summary : Populations of the Asian corn borer, Ostrinia furnacalis (Guenee), were monitored using water pan baited with a virgin female, crude pheromone extract, and kerosene light trap on a farmer's field in Damnernsaduak, Thailand, during the dry and wet seasons of 1988. The virgin female was found to be the most efficient bait, followed by kerosene light trap and crude pheromone extract. The virgin female was found to attract males from a distance of at least 30 meters. Water hyacinths, Eichornia crassipes, growing on both sides of the canal beside the corn field, were used by the corn borer moths as breeding sites. The population of the corn borer agg parasite, Trichogramma australicum Girault, was monitored. High levels of egg parasitism were observed toward crop maturity while the number of egg masses declined. Damaged plants were observed three weeks after corn borer egg deposition in both dry and wet seasons; damage levels increased with crop age. The experimental corn yield was only about half of the potential yield because of uncontrolled damage by birds, cutworms, earworms, and humans, in addition to that caused by the corn borer. The Philippine corn borer model was adapted to Thailand conditions. The computer program was written in Turbo Pascal version 3 to run in an IBM PC compatible computer. Two versions of the model were produced: with and without egg parasitism. Inputs to the model were the first 21 days catch of the virgin female bait trap and the mean daily temperature. The model without egg parasitism simulated higher population level at 80-110 days after emergence (DAE) than the observed. The model was fitted to the egg population. Model prediction of peaks of the other stages differed from the observed by 3-12 days. The revised model with egg parasitism simulated similar population trends. The performance of the Philippine and Thai Asian corn borer models was compared. Both models simulated the same population peaks.