Biting deterrence and insecticidal activity of hydrazide‐hydrazones and their corresponding 3‐acetyl‐2,5‐disubstituted‐2,3‐dihydro‐1,3,4‐oxadiazoles against Aedes aegypti

• Published in: Pest management science 2013-06, Vol.69 (6), p.703-708
• Main Authors: Tabanca, Nurhayat, Ali, Abbas, Bernier, Ulrich R, Khan, Ikhlas A, Kocyigit‐Kaymakcioglu, Bedia, Oruç‐Emre, Emine E, Unsalan, Seda, Rollas, Sevim
• Format: Article
• Language: English
• Subjects: 1,3,4‐oxadiazoles; 4-oxadiazoles; Aedes - drug effects; Aedes - physiology; Aedes aegypti; Animals; Behavior, Animal - drug effects; bioassays; Biological and medical sciences; biting deterrent; bromine; Chemical compounds; Control; deet; fluorine; Fundamental and applied biological sciences. Psychology; Humans; hydrazide-hydrazones; hydrazides; Hydrazones - pharmacology; Insect Bites and Stings - prevention & control; Insect Repellents - pharmacology; insecticidal properties; Insecticides; larvae; larvicidal; lethal dose 50; Medically important nuisances and vectors, pests of stored products and materials: population survey and control; Mortality; Mosquitoes; Oxadiazoles - pharmacology; Pest control; Phytopathology. Animal pests. Plant and forest protection; Protozoa. Invertebrates; repellent; screening; Vectors. Intermediate hosts; volunteers
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.3424

BACKGROUND: Taking into account the improvement in insecticidal activity by the inclusion of fluorine in the hydrazone moiety, the authors synthesized new 4‐fluorobenzoic acid hydrazides and 3‐acetyl‐2,5‐disubstituted‐2,3‐dihydro‐1,3,4‐oxadiazoles, substituting a phenyl group or a heteroaryl ring carrying one or two atoms of F, Cl and Br, and investigated their biting deterrent and larvicidal activities against Aedes aegypti for the first time. RESULTS: The compound 3‐acetyl‐5‐(4‐fluorophenyl)‐2‐[4‐(dimethylamino)phenyl]‐2,3‐dihydro‐1,3,4‐oxadiazole (17) produced the highest biting deterrent activity (BDI = 1.025) against Ae. Aegypti, followed by 4‐fluorobenzoic acid [(phenyl)methylene] hydrazide (1). These activity results were similar to those of N,N‐diethyl‐meta‐toluamide (DEET), which showed a proportion not biting of 0.8–0.92. When compounds 1 and 17 were tested on cloth worn on human volunteers, compound 1 was not repellent for some volunteers until present in excess of 500 nmol cm⁻², while compound 17 was not repellent at the highest concentration tested (1685 nmol cm⁻²). In the larvicidal screening bioassays, only compounds 10, 11, 12 and 17 showed 100% mortality at the highest screening dose of 100 ppm against Ae. aegypti larvae. Compounds 11 and 12 with LD₅₀ values of 24.1 and 30.9 ppm showed significantly higher mortality than 10 (80.3 ppm) and 17 (58.7 ppm) at 24‐h post‐treatment. CONCLUSION: The insecticidal and biting deterrent activities were correlated with the presence of a halogen atom on the phenyl or heteroaryl substituent of the hydrazone moiety.