Significant reduction in abundance of peridomestic mosquitoes (Culicidae) and Culicoides midges (Ceratopogonidae) after chemical intervention in western São Paulo, Brazil Mikel A.

MIKEL A. GONZALEZ; SPINELLI, GUSTAVO; ORIN COURTENARY; MARIA M. RONDEROS; JAMES G. C. HAMILTON; ERIN DILGER; ORIN COURTENAY; JAMES HAMILTON

PARASITES AND VECTORS

BIOMED CENTRAL LTD

Lugar: Londres; Año: 2020

1756-3305

Background: We assessed the impact of two sand fly insecticide interventions (insecticide spraying and insecticideimpregnateddog collars) on the peridomestic abundance and distribution of mosquitoes (Culicidae) and bitingmidges (Ceratopogonidae) in western São Paulo (Brazil) in a long-term (42-month) evaluation. Both of these dipterangroups are vectors of diseases of medical and veterinary relevance to humans and domestic animals in Brazil.Methods: The interventions in the 3-arm stratified randomised control trial were: pheromone + insecticide (PI)(chicken roosts were sprayed with microencapsulated lambda-cyhalothrin; pheromone lure has no effect on the Dipterapests studied here); dog-collars (DC) (dogs fitted with deltamethrin-impregnated collars); and control (C) (unexposedto pyrethroids) were extended by 12 months. During that time, adult mosquitoes and midges were sampledalong 280 households at three household locations (inside human dwellings, dog sleeping sites and chicken roosts).Results: We collected 3145 culicids (9 genera, 87.6% Culex spp.) distributed relatively uniformly across all 3 arms: 41.9% atchicken roosts; 37.7% inside houses; and 20.3% at dog sleeping sites. We collected 11,464 Culicoides (15 species) found mostlyat chicken roosting sites (84.7%) compared with dog sleeping sites (12.9%) or houses (2.4%). Mosquitoes and Culicoides weremost abundant during the hot and rainy season. Increased daytime temperature was marginally associated with increasedmosquito abundance (Z = 1.97, P = 0.049) and Culicoides abundance (Z = 1.71, P = 0.087). There was no significant associationwith daily average rainfall for either group. Household-level mosquito and midge numbers were both significantly reduced bythe PI intervention 56% [incidence rate ratio, IRR = 0.54 (95% CI: 0.30?0.97), P ≤ 0.05] and 53% [IRR = 0.47 (95% CI: 0.26?0.85),P ≤ 0.05], respectively, compared to the control intervention. The abundance of both dipteran groups at dog sleeping sites waslargely unaffected by the PI and DC interventions. The PI intervention significantly reduced abundance of mosquitoes insidehouses (41%) and at chicken roosting sites (48%) and reduced midge abundance by 51% in chicken roosting sites.