The influence of insecticide-pheromone substitution on the abundance and distributional pattern of soil oribatid mites

A comparative study has been made on the abundance and distributional pattern of soil oribatid mites in an Egyptian cotton field. Samples were collected from two pesticide-treated fields (profenofos, chlorofluazuron, fenvalerate) and a control plot where cotton bollflies and leaf-flies were caught using pheromone traps. Sampling was done monthly, from the period of early cultivation of the cotton until the crop was full grown. The scheme concerning the dominance classification was adopted. Aggregation of the dominant species was estimated in relation to insecticide effect. Rhysotritia ardua ardua appeared to be insecticide-loving species (insecticide-resistant species) and was not influenced either by the sort of insecticide or by its quantity. Multiple application of two insecticides has a significant negative effect on the abundance of Scheloribates laevigatus. Zygoribatula exarata and Xylobates capucinus were considered good bioindicators for pesticide-untreated field. It can be suggested that the substitution of insecticide with pheromone trap can produce a greater, more stabilized community and a high productive agroecosystem. Accordingly, our findings support the current tendency to replace chemical control of pests with pheromone traps which seem to be a good tool compared with pesticide application in all cotton fields and oribatid mites may be useful test species for risk evaluation of soil contamination by pesticides.