Abstract:

【Objective】 Hypopus of Rhizoglyphus echinopus has good resistance to the adverse environmental conditions and acaricide. In order to understand the effects of acaricides at sublethal dose on hypopus formation and completion, a series of experiments were conducted. 【Method】 The dry residual film method was applied to test the toxicity of six acaricides to protonymphs and hypopi of Rhizoglyphus echinopus. The effects of sublethal doses (LC20) of abamectin and hexythiazox on hypopus formation and completion were also studied. 【Result】 The toxity line of abamectin EC and hexythiazox EC on protonymphs were y=1.2986+0.7549x and y=1.2866+1.1189x, the toxity line of abamectin EC and hexythiazox EC on hypopus were y=1.2986+0.7549x and y= -2.3442+1.3936x .The hypopus formation was not significantly affected by 1.8% abamectin EC and 5% hexythiazox EC (P＞0.05), however, only a few hypopi treated by two acaricides could reach the tritonymph stage in 49 days, 13.44% and 3.11%, respectively. 【Conclusion】 Sublethal doses (LC20) of abamectin and hexythiazox have a little influce on formation of hypopi of Rhizoglyphus echinopus, but have a great influnce on its completion.

Key words: acaricide, Rhizoglyphus echinopus, toxicity, sub-lethal dose, hypopus