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

ABSTRACT

Deltamethrin-impregnated PVC dog collars were tested to assess if they were effective in protecting dogs from sand fly bites of Lutzomyia longipalpis and Lu. migonei. A protective effect against Old World species Phlebotomus perniciosus 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 outskirts of Fortaleza in Cearß, Brazil. Periodically, a dog from each group was sedated, placed in a net cage for 2 h in which 150 female sand flies had been released 10-15 min before. Lu. longipalpis were used 4, 8, 12, 16, 22, 27, and 35 weeks after the attachment of the collars. Lu. migonei were used 3, 7, 11, 15, 22, 26, and 36 weeks after attachment. During 35 weeks, only 4.1 percent (81 of 2,022) Lu. longipalpis recovered from the nets with the deltamethrin collared dogs were engorged, an anti-feeding effect of 96 percent. Mortality initially was over 90 percent and at 35 weeks was 35 percent with half of the sand flies dying in the first 2 h. In contrast, 83 percent of the 2,094 Lu. longipalpis recovered from the nets containing the untreated collared dogs were engorged and the mortality ranged from zero to 18.8 percent on one occasion with 1.1 percent dying in the first 2 h. Similar findings were found with Lu. migonei of 2,034 sand flies recovered over this period, only 70 were engorged, an anti-feeding effect of 96.5 percent, and mortality ranged from 91 percent initially to 46 percent at 36 weeks. In contrast, engorgement of controls ranged from 91 to71 percent and a mortality ranged from 3.5 to 29.8 percent. These studies show that deltamethrin impregnated collars can protect dogs against Brazilian sand flies for up to eight months. Thus, they should be useful in a program to control human and canine visceral leishmaniasis