Optimization of pheromone dispenser density for managing the rice striped stem borer, Chilo suppressalis (Walker), by mating disruption

The rice striped stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae) is one of the most important rice pests worldwide, Rice is frequently grown in an intensive production system in areas adjacent to environmentally sensitive areas. Therefore, the use of insecticides is problematic and new techniques, including mating disruption, are being introduced. Due to the high cost of pheromones, it is essential to optimize the density of the pheromone dispensers. The main purpose of this research was to determine the minimal dosage and optimal dispenser distribution for effective mating disruption of C. suppressalis. To this end, we conducted a wide-area trial to test several dispenser densities. 31, 25 and 16 dispensers/ha during 3 years. Results were compared with a standard mating disruption treatment (51 dispensers/ha) and a standard aerial chemical treatment with tebufenozide. Treatment efficacy was determined by pheromone trap catches and crop damage assessment. The release rate of the pheromone dispensers was also quantified. The results of these trials suggest that such treatments provide effective pest control even with reduced pheromone dispenser densities. Longer-lasting dispensers with lower residual load at the end of trials will greatly improve the efficacy of mating disruption for C. suppressalis. Moreover, an important consideration is that these newly tested dispenser densities imply a significant reduction in the cost of the treatment. These results are essential in order to expand the use of mating disruption in rice crop protection. (C) 2009 Elsevier Ltd. All rights reserved.