piperidines and pirimiphos-methyl

The spread of resistance to pyrethroids in the major Afrotropical malaria vectors Anopheles gambiae s.s. necessitates the development of new strategies to control resistant mosquito populations. To test the efficacy of nets treated with repellent and insecticide against susceptible and insecticide-resistant An. gambiae mosquito populations, we impregnated mosquito bed nets with an insect repellent mixed with a low dose of organophosphorous insecticide and tested them in a rice-growing area near Bobo-Dioulasso, Burkina Faso. During the first 2 weeks posttreatment, the mixture was as effective as deltamethrin alone and was more effective at killing An. gambiae that carried knockdown resistance (kdr) or insensitive acetylcholinesterase resistance (Ace1R) genes. The mixture seemed to not kill more susceptible genotypes for the kdr or Ace1R alleles. Mixing repellents and organophosphates on bed nets could be used to control insecticide-resistant malaria vectors if residual activity of the mixture is extended and safety is verified.

Topics: Acetylcholinesterase; Alleles; Animals; Anopheles; Burkina Faso; Cholinesterase Inhibitors; DEET; Female; Genes, Insect; Humans; Insect Repellents; Insect Vectors; Insecticide Resistance; Insecticides; Malaria; Male; Mosquito Control; Nitriles; Organothiophosphorus Compounds; Piperidines; Pyrethrins

To manage the kdr pyrethroid-resistance in Anopheline malaria vectors, new compounds or new strategies are urgently needed. Recently, mixing repellents (DEET) and a non-pyrethroid insecticide (propoxur) was shown to be as effective as deltamethrin, a standard pyrethroid, under laboratory conditions, because of a strong synergy between the two compounds. In the present study, the interactions between two repellents (DEET and KBR 3023) and a non-pyrethroid insecticide (pyrimiphos methyl or PM) on netting were investigated. The residual efficacy and the inhibition of blood feeding conferred by these mixtures were assessed against Anopheles gambiae mosquitoes.. DEET and KBR 3023 were mixed with pyrimiphos methyl (PM), a organophosphate (OP) insecticide. The performance of mono- and bi-impregnated nets against adult mosquitoes was assessed using a miniaturized, experimental hut system (laboratory tunnel tests) that allows expression of behavioural responses to insecticide, particularly the mortality and blood feeding effects.. Both mixtures (PM+DEET and PM+KBR3023) induced 95% mortality for more than two months compared with less than one week for each compound used alone, then reflecting a strong synergy between the repellents and PM. A similar trend was observed with the blood feeding rates, which were significantly lower for the mixtures than for each component alone.. Synergistic interactions between organophosphates and repellents may be of great interest for vector control as they may contribute to increase the residual life of impregnated materials and improve the control of pyrethroid-resistance mosquitoes. These results prompt the need to evaluate the efficacy of repellent/non-pyrethroid insecticide mixtures against field populations of An. gambiae showing high level of resistance to Ops and pyrethroids.

Topics: Animals; Anopheles; Bedding and Linens; DEET; Drug Synergism; Feeding Behavior; Female; Guinea Pigs; Insect Repellents; Insect Vectors; Insecticides; Mosquito Control; Organophosphates; Organothiophosphorus Compounds; Piperidines; Pyrethrins

A methanol extract of Piper longum fruit was found to be active against mosquito larvae of Culex pipiens pallens at 10 microg/ml after 24 h. A piperidine alkaloid, pipernonaline, was found to be responsible for this activity, with the 24-h median lethal dose (LD50) value for this compound being 0.21 mg/liter. The LD50 value of pipernonaline was not much higher than those for the 3 organophosphorous insecticides malathion, chlorpyrifos-methyl, and pirimiphos-methyl, used for comparative purpose in this study. Structural elucidation of pipernonaline was by means of mass spectrometry (1H and 13C nuclear magnetic resonance imaging).

Topics: Alkaloids; Animals; Capsicum; Chlorpyrifos; Cholinesterase Reactivators; Culex; Insecticides; Larva; Lethal Dose 50; Malathion; Organothiophosphorus Compounds; Piperidines; Plants, Medicinal