Mosquitocidal activity of p,p’-difluoro-diphenyl-trichloroethane (DFDT)

• Published in: Pesticide biochemistry and physiology 2020-11, Vol.170, p.104686, Article 104686
• Main Authors: Norris, Edmund J., Demares, Fabien, Zhu, Xiaolong, Bloomquist, Jeffrey R.
• Format: Article
• Language: English
• Subjects: Aedes - drug effects; Aedes aegypti; Animals; Anopheles gambiae; Biphenyl Compounds; DDT; DDT - toxicity; DFDT; Drosophila melanogaster - drug effects; Drosophila melanogaster - genetics; Insecticide; Insecticide Resistance - drug effects; Insecticides - pharmacology; Insecticides - toxicity; Mosquito Vectors; Puerto Rico; Pyrethrins - toxicity; Trichloroethanes
• ISSN: 0048-3575; 1095-9939
• DOI: 10.1016/j.pestbp.2020.104686

New insecticides are urgently needed for the control of arthropod vectors of public health diseases. As resistance to many insecticides used for the control of public health pests is ubiquitous, all available chemistries should be evaluated for their potential to effectively control both insecticide-susceptible and insecticide-resistant strains of mosquitoes. This study aimed to evaluate p-p’-difluoro-diphenyl-trichloroethane (DFDT) as a mosquito control technology and relate its activity to that of DDT. We found that topical DFDT was significantly less toxic than DDT to both pyrethroid-susceptible and pyrethroid-resistant strains of Anopheles gambiae and Aedes aegypti. Direct nervous system recording from Drosophila melanogaster CNS demonstrated that DFDT is approximately 10-times less potent than DDT at blocking nerve firing, which may explain its relatively lower toxicity. DFDT was shown to be at least 4500 times more vapor-active than DDT, with an LC50 in a vapor toxicity screening assay of 2.2 μg/cm2. Resistance to DFDT was assessed in two mosquito strains that possess target-site mutations in the voltage-gated sodium channel and upregulated metabolic activity. Resistance ratios for Akdr (An. gambiae) and Puerto Rico (Ae. aegypti) strains were 9.2 and 12.2, respectively. Overall, this study demonstrates that DFDT is unlikely to be a viable public health vector control insecticide. [Display omitted] •DFDT is less toxic than DDT topically applied to Aedes aegypti and Anopheles gambiae mosquitoes•Significant resistance was observed for DDT and DFDT on pyrethroid-resistant strains of Aedes aegypti and Anopheles gambiae•DFDT was considerably less effective at producing nerve block in Drosophila melanogaster central nervous system recordings•DFDT is more vapor toxic than DDT and may explain its relatively higher speed of action observed by other researchers.