Toward an effective and sustainable management of the dubas bug: integrating chemical, biological, physical, and cultural controls
Abstract: The dubas bug has been a major pest of date palms in the region since the 1920s. In Oman, date palms have been seasonally treated with insecticides aerially and from the ground for more than 45 years, but this pest has persisted at high densities in many sites. It is suspected that continuous use of insecticides has led to the development of resistance and reduction in natural enemy populations. We have conducted studies on this pest in Oman, focusing on natural enemies, sampling methods, systemic insecticides, pruning, and factors affecting its density and distribution. We recorded the following natural enemies of this pest: two egg parasitoids, one nymphal-adult parasitoid, and at least 10 predatory species of the orders Araneae, Mantodea, Neuroptera, Hymenoptera, and Coleoptera. To increase the efficiency of these natural control agents, we are suggesting an integrated management strategy that avoids the sole reliance on aerial and ground-based spraying. The core of this strategy is seasonal and well-timed systemic insecticides applied, as soil drench, only when dubas bug populations reach a high economic threshold level based on pre-season egg density, a commonly used direct and indirect determination of nymphs-adult density at about midseason. The strategy also includes pre-season pruning of the lower whorl of leaves containing viable eggs of the dubas bug, combined with proper planting distance of trees. Additionally, it is important to plant less susceptible good-quality cultivars, and to have a greater variety of select crops and non-crops in the understory of trees and in their vicinity for a more enhanced environment for natural enemies.