Effects of Adjuvants on the Efficacy of Certain Insecticides Against Ommatissus lybicus Bergevin (Hem.: Tropiduchidae) in Iran

Dubas bug, Ommatissus lybicus, is one of the key pests of date palm in Iran. Chemical control is the most conventional control method of this dangerous pest in the outbreak regions. The aim of this investigation was to determine whether adjuvants increase effectiveness of insecticides. The study was conducted in two trials. The first trial treatment included imidacloprid SC350 and clothianidin WG500 with concentration of 0.2g/l was applied separately or mixed with Jonobegan® (0.5ml/l), or with Hiomix® (0.5ml/l) as adjuvants, diazinon EC600 (2ml/l) as recommended insecticide. Moreover, the control was without treatment. The second trial treatment included diazinon EC600 (2ml/l), chlorpyrifos methyl (EC400) (1ml/l), fenitrothion EC500 (1ml/l), chlorpyrifos ethyl EC408 (2.5ml/l) was tested separately or mixed with Dioclean® (0.5ml/l) against dubas bug. Both of trials conducted with 3 replications in randomized complete block design. The nymph population and numbers of honeydew drops were recorded 1 day before and 3, 7, 14 days after treatment. The results showed that efficacy of clothianidin, clothianidin plus Hiomix® and clothianidin plus Jonobegan® were 81.47, 90.8 and 96.4%, respectively, whereas efficacy of imidacloprid with the last arrangement were 92.17, 91.93 and 90.63%. The residual toxicity of neonicotinoids separately and mixed with Hiomix® or Jonobegan® against dubas bug was significantly extended in comparison to diazinon (69%). The feeding index of treatments showed that the Jonobegan® could be a better adjuvant for clothianidin. The results also revealed that fenitrothion (77%) and chlorpyrifos ethyl (28.5%) had the highest and the lowest efficacy in comparison with organophosphorus insecticides as alone, but all of the organophosphorus insecticides mixed with Dioclean®, had a similar efficacy (except chlorpyrifos ethyl).