Evaluation of azadirachtin A formulations for the control of dubas bug on date palm in Oman

摘要

The dubas bug Ommatissus lybicus attacks date palm twice a year in the Sultanate of Oman and it is considered the most important pest of this tree. Currently, the government subsidises the control of this pest by paying for applications of synthetic insecticides in plantations that experience pest outbreaks. The aim of the research that is described in this paper was to evaluate whether environmentally benign neem formulations might make a contribution to the management of the dubas bug, perhaps as alternatives to the organosphosphate insecticides in use at present. The dubas bug population was monitored in a plantation on the Batinah coast over a 6 month period from January - June 2005. Direct measurements of pest numbers were made by counting nymphs on leaflets on suckers at the base of trees that are located at a height of about 1 metre. Indirect measurements of pest numbers were made by recording honeydew droplets on water sensitive papers. The data collected indicated a high degree of correlation between direct and indirect counts however, the pest population did not approach a level that would have required chemical intervention. Laboratory studies with field collected dubas bug nymphs were undertaken in which three different neem formulations were evaluated in relation to their topical toxicity to the pest. The highest mortality recorded from the topical toxicity bioassays was approximately 30%. This was with a formulation that comprised 17% of the active ingredient Azadirachtin A. The data collected are therefore preliminary. It is hoped that field trials will be undertaken later on this year.