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

Abstract

Background We assessed the impact of two sand fly insecticide interventions (insecticide spraying and insecticide-impregnated dog collars) on the peridomestic abundance and distribution of mosquitoes (Culicidae) and biting midges (Ceratopogonidae) in western São Paulo (Brazil) in a long-term (42-month) evaluation. Both of these dipteran groups 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 Diptera pests studied here); dog-collars (DC) (dogs fitted with deltamethrin-impregnated collars); and control (C) (unexposed to pyrethroids) were extended by 12 months. During that time, adult mosquitoes and midges were sampled along 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% at chicken roosts; 37.7% inside houses; and 20.3% at dog sleeping sites. We collected 11,464 Culicoides (15 species) found mostly at chicken roosting sites (84.7%) compared with dog sleeping sites (12.9%) or houses (2.4%). Mosquitoes and Culicoides were most abundant during the hot and rainy season. Increased daytime temperature was marginally associated with increased mosquito abundance (Z = 1.97, P = 0.049) and Culicoides abundance (Z = 1.71, P = 0.087). There was no significant association with daily average rainfall for either group. Household-level mosquito and midge numbers were both significantly reduced by the 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 was largely unaffected by the PI and DC interventions. The PI intervention significantly reduced abundance of mosquitoes inside houses (41%) and at chicken roosting sites (48%) and reduced midge abundance by 51% in chicken roosting sites. Conclusions Sprayed insecticide at chicken roosting sites reduced the abundance of mosquitoes and midges at the peridomestic level while dog collars had no effect on numbers for any group.

Species Diversity, Habitat Distribution, and Blood Meal Analysis of Haematophagous Dipterans Collected by CDC-UV Light Traps in the Dominican Republic

“…Similarly, although with less information available, C. pusillus is also a possible BTV vector [ 46 ], commonly found in farm holdings. Both species are often trapped in association with cattle and pigs in pasture environments [ 49 , 50 ], and to a lesser extent, in poultry environments [ 51 , 52 ].…”

Effectiveness of Aedes-borne infectious disease control in Latin America and the Caribbean region: A scoping review

“…Other studies also demonstrated the benefits of combined interventions [33,41,51,63,84,85]. In Brazil, one study that combined the application of insecticide temephos, environmental management and health education campaigns did not observe positive results [35].…”

An Overview of the Management of Mansonellosis

“…[45][46][47][48] Thus while the outdoor biting habits of the simuliid filarial vectors of the Amazon are reasonably well characterised, 40 the behavioural ecology of the South American ceratopogonids involved in M. ozzardi transmission (and presumably M. perstans transmission) is not well understood. 1,2,40,45 Although, thus, one study recently showed that IRS treatment of homes and animal shelters can be used to decrease the abundance of adult Culicoides, 49 whether this approach will be effective for mansonellosis control will depend a great on the biting and resting habits of the most important vectors, which are still to be determined-not just in Latin America, but globally. 1,2 https://doi.org/10.2147/RRTM.S274684…”