Individual and combined effects of insecticides, inert dusts and high temperatures on Callosobruchus maculatus (coleoptera: Chrysomelidae)
2020
Karimzadeh, Roghaiyeh | Javanshir, Mina | Hejazi, Mir Jalil
In this study individual and combined effects of some chemical and physical factors including cypermethrin, dichlorvos, ash, kaolin and high temperatures were assessed on adults of cowpea seed beetle Callosobruchus maculatus (F.) at laboratory conditions. The adults were exposed to the studied factors on concrete arenas prepared in plastic Petri dishes. Twenty up to 24 h old adults were released in each Petri dish, and their mortality was recorded 72 h after treatment. The LC₂₅ values of the insecticides, LD₂₅ values of the inert dusts and LTi₂₅ values of high temperatures were estimated and used for determining combination effects of the two factors. To determine combination effects of three factors, LC₁₅ values of insecticides, LD₁₅ values of inert dusts and LTi₁₅ values of high temperatures were estimated and used in the bioassays. The LC₅₀ and LD₅₀ values for cypermethrin, dichlorvos, ash and kaolin were 1286.96 mg a. i./L, 1350.55 mg a. i./L, 36.64 g/m² and 45.18 g/m², respectively. The LTi₅₀ values at 45, 48, 50, 52 and 55 °C were 34, 29, 18, 11 and 8 min, respectively. The results indicated that the effect of simultaneous exposure to cypermethrin, high temperatures and ash or kaolin was significantly more than sum of individual effects of these factors. It means the effects of cypermethrin, high temperatures and inert dusts were synergized by each other. If similar treatments performed at larger scales give comparable results, it may be concluded that reduced dosage of cypermethrin, high temperatures and ash or kaolin combinations would be effective alternative control methods and can be used in cowpea seed beetle management programs.
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