Resistance and biotic potential of mites-phytophagans in presence of application of acaricides

Abstract

The objective of the study was to assess the resistance of mites-phytophagans to acaricides on the basis of changes in the biotic potential. Research methods were common for entomology and plant protection techniques to identify and record the number of phytophagans in the fruit orchards: route examination, visual account under a binocular microscope. Biological efficiency of acaricides against spider mites was determined by Henderson-Tilton formula. Demographic indicators of the development of fruit tree red and hawthorn spiders were calculated according to the "Guidelines for the compilation of tables for the survival of insects and mites". As a result of research it has been established that the species composition of mites-phytophagans in the fruit orchards of the Crimea is quite labile and is subject to a constant shift in the proportion of species. The decrease in biological efficiency after repeated use of the same preparations and the appearance of mites phytophagans’ races, resistant to these preparations, have been determined. A comparative assessment of the biotic potential of fruit tree red and hawthorn spiders on apple trees in the presence of acaricides’ application is given. Value of pure reproduction (R_0.> 1) indicates the ability of the fruit tree red spider population to recover and develop resistance to five acaricides: Envidor, KS; Ortus, SP; Sanmite, SP; Demitan, 200 SC and Masai, SP. Hawthorn spider developed resistance to two acaricides. When using insectoacaricides Kraft, VDG and Oberon Rapid, KS, (R₀)_. <1, what indicates that the pest population is decreasing. Conclusion. In order to avoid the emergence of resistant races of mites-phytophagans, the preparations should be alternated with various active substances. The preparations from the group of avermectins are to use no more than 2 times per season.