effects of cold pre-treatment on the toxicity of several contact insecticides on adults of three Sitophilus granarius (L.) populations

• Published in: Journal of pest science 2014-06, Vol.87 (2), p.301-308
• Main Authors: Kljajić, Petar, Andrić, Goran, Pražić-Golić, Marijana, Inđić, Dušanka, Vuković, Slavica
• Format: Article
• Language: English
• Subjects: Adults; Agriculture; Biomedical and Life Sciences; Brittleness; Cold; Cold treatment; Cooling; Cooling effects; Deltamethrin; Dichlorvos; Ecology; Entomology; Exposure; Forestry; Insecticides; Insects; Laboratories; Life Sciences; Malathion; Original Paper; Pesticides; Plant Pathology; Plant Sciences; Populations; Pretreatment; Recovery; Sitophilus granarius; storage insects; Toxicity
• ISSN: 1612-4758; 1612-4766
• DOI: 10.1007/s10340-014-0552-z

As very little is known about the impact of cold pre-treatments on insecticidal toxicity to the surviving stored-product insects, we examined the effects of cooling (−5 °C) on the toxicity of five contact insecticides to Sitophilus granarius adults from three populations (laboratory, field and selected). We determined: (a) weevil lethal time after exposure to −5 °C, (b) the effects of two cold pre-treatments (LT₂₀ and LT₅₀—lethal time for 20 and 50 % of exposed adults) on 24 and 72 h recovery rates of laboratory adults after exposure to five insecticides and (c) deltamethrin, dichlorvos and malathion toxicity to two weevil populations with altered insecticide susceptibility after exposure to the LT₂₀ and LT₅₀ pre-treatments. The tested S. granarius populations showed no significant differences in their susceptibility to cooling. All insecticides except dichlorvos were more toxic to the laboratory weevils after 24 h than after 72 h recovery from the LT₂₀ pre-treatment. Dichlorvos and deltamethrin were more toxic to the other two populations after 72 h of recovery. Comparing the effects of cold pre-treatment and non-treatment on the laboratory strain, no significant increase in the toxicity of insecticides was detected, while only deltamethrin was significantly more toxic to the field and selected populations recovering for 24 h (12.1 and 11.0 times, respectively) and 72 h (6.9 and 36.6 times) from the LT₂₀ pre-treatment. In conclusion, only the shorter of the two cold pre-treatments was found effective in terms of increasing the insecticidal toxicity, especially against the populations with altered susceptibility to insecticides.