Insecticidal, acaricidal and repellent effects of DEET- and IR3535-impregnated bed nets using a novel long-lasting polymer-coating technique.
A novel long-lasting repellent-treated net (LLRTN) has been designed by binding the skin repellents N,N-diethyl-m-toluamide (DEET), or IR3535, onto the fibres of bed net fabric using a new polymer-coating technique. The repellent toxicological effectiveness and residual activity of a factory-based repellent-impregnated fabric has been evaluated by laboratory testing against adult Aedes aegypti mosquitoes and nymphal Ixodes ricinus ticks. By using this repellent-embedding impregnation technique, concentrations exceeding 10 g/m(2) could be achieved with one single polymer layer. Both DEET- and IR3535-impregnated fabrics revealed a dose-dependent insecticidal as well as acaricidal activity. One hundred percent knockdown times of DEET-treated bed nets ranged from 187.5 +/- 31.8 to 27.5 +/- 3.5 min against A. aegypti, and between 214 +/- 47 and 22.6 +/- 5 min against nymphal I. ricinus, linked to a DEET concentration of 1.08 and 10.58 g/m(2), respectively. With IR3535, A. aegypti produced dose-dependent 100% knockdown times varying from 87.5 +/- 10.6 to 57.5 +/- 3.5 min and between 131.4 +/- 6.5 and 33.8 +/- 5 min against nymphal I. ricinus, respectively, linked to concentrations between 1.59 and 10.02 g/m(2). One hundred percent repellency measured by complete landing and biting protection of impregnated fabric by using the arm-in-cage test could be achieved at DEET concentrations exceeding 3.7 to 3.9 g/m(2), and for IR3535 concentrations over 10 g/m(2). One hundred percent landing and biting protection could be preserved with DEET-treated fabrics for 29 weeks at an initial concentration of 4.66 g/m(2), 54 weeks at 8.8 g/m(2), 58 weeks at 9.96 g/m(2) and 61 weeks at 10.48 g/m(2) for DEET, and 23 weeks for IR3535-treated fabric at a concentration of 10.02 g/m(2). Unlike repellent-treated fabric, a brand of a commercially available long-lasting insecticide-treated net tested containing 500 mg permethrin/m(2) did not protect from mosquito bites. First results on bioactivity and long-lasting efficacy show that the new LLRTN technique is highly promising as a potential candidate for future malaria control strategies, especially in areas where pyrethroid resistance occurs.
Faulde
Michael K
MK
Department of Medical Entomology/Zoology, Central Institute of the Bundeswehr Armed Forces Medical Service, Koblenz, Germany. MichaelFaulde@bundeswehr.org
Albiez
Gunther
G
Nehring
Oliver
O
D000330:Aedes / Q000187:drug effects; D000818:Animals; D003671:DEET / Q000494:pharmacology*; D003692:Delayed-Action Preparations; D004337:Drug Carriers / Q000737:chemistry*; D005260:Female; D006801:Humans; D007302:Insect Repellents / Q000494:pharmacology*; D057148:Insecticide-Treated Bednets; D007306:Insecticides / Q000494:pharmacology*; D018884:Ixodes / Q000187:drug effects; D011108:Polymers / Q000737:chemistry*; D011422:Propionates / Q000494:pharmacology*; D016019:Survival Analysis; D013997:Time Factors
D003692:Delayed-Action Preparations; D004337:Drug Carriers; D007302:Insect Repellents; D007306:Insecticides; D011108:Polymers; D011422:Propionates; D003671:DEET; C462400:ethyl-3-(N-n-butyl-N-acetyl)aminopropionate