Deltamethrin-impregnated dog collars have a potent anti-feeding and insecticidal effect on Lutzomyia longipalpis and Lutzomyia migonei

Deltamethrin-impregnated PVC dog collars were tested to assess if they were effective in protecting dogs from sandfly bites of Lutzomyia longipalpis a nd Lu. migonei. A protective effect against Old World species Phlebotomus p erniciosus was demonstrated before. Four dogs wearing deltamethrin collars and three dogs wearing untreated collars (not impregnated with deltamethrin ) were kept in separate kennels for over eight months in a village on the o utskirts of Fortaleza in Ceara, Brazil. Periodically, a dog from each group was sedated, placed in a net cage for 2 h in which 150 female sandflies ha d been released 10-15 min before. Lu. longipalpis were used 4, 8, 12, 16, 2 2, 27, and 35 weeks after the attachment of the collars. Lu. migonei were u sed 3, 7, 11, 15, 22, 26, and 36 weeks after attachment. During 35 weeks, o nly 4.1% (81 of 2,022) Lu. longipalpis recovered from the nets with the del tamethrin collared dogs were engorged, an anti-feeding effect of 96%. Morta lity initially was over 90% and at 35 weeks was 35% with half of the sandfl ies dying in the first 2 h. In contrast, 83% of the 2,094 Lu. longipalpis r ecovered from the nets containing the untreated collared dogs were engorged and the mortality ranged from zero to 18.8% On one occasion with 1.1% dyin g in the first 2 h. Similar findings were found with Lu. migonei: of 2,034 sandflies recovered over this period, only 70 were engorged, an anti-feedin g effect of 96.5%, and mortality ranged from 91% initially to 46% at 36 wee ks. In contrast, engorgement of controls ranged from 91 to 71% and a mortal ity ranged from 3.5 to 29.8%. These studies show that deltamethrin impregnated collars can protect dogs a gainst Brazilian sand flies for up to eight months. Thus, they should be us eful in a program to control human and canine visceral leishmaniasis.