3D mosquito screens to create window double screen traps for mosquito control

Abstract

Background: Mosquitoes are vectors for many diseases such as malaria. Insecticide-treated bed nets and indoor residual spraying of insecticides are the principal malaria vector control tools used to prevent malaria in the tropics. Other interventions aim at reducing man-vector contact. For example, house screening provides additive or synergistic effects to other implemented measures. We used commercial screen materials made of polyester, polyethylene or polypropylene to design novel mosquito screens that provide remarkable additional benefits to those commonly used in house screening. The novel design is based on a double screen setup made of a screen with 3D geometric structures parallel to a commercial mosquito screen creating a trap between the two screens. Owing to the design of the 3D screen, mosquitoes can penetrate the 3D screen from one side but cannot return through the other side, making it a unidirectional mosquito screen. Therefore, the mosquitoes are trapped inside the double screen system. The permissiveness of both sides of the 3D screens for mosquitoes to pass through was tested in a wind tunnel using the insectary strain of Anopheles stephensi.

Results: Among twenty-five tested 3D screen designs, three designs from the cone, prism, or cylinder design groups were the most efficient in acting as unidirectional mosquito screens. The three cone-, prism-, and cylinder-based screens allowed, on average, 92, 75 and 64% of Anopheles stephensi mosquitoes released into the wind tunnel to penetrate the permissive side and 0, 0 and 6% of mosquitoes to escape through the non-permissive side, respectively.

Conclusions: A cone-based 3D screen fulfilled the study objective. It allowed capturing 92% of mosquitoes within the double screen setup inside the wind tunnel and blocked 100% from escaping. Thus, the cone-based screen effectively acted as a unidirectional mosquito screen. This 3D screen-based trap design could therefore be used in house screening as a means of avoiding infective bites and reducing mosquito population size.

Keywords: 3D-screen; Control; Mosquito; Trap; Window.

Fig. 1

Screen materials. a-d B1w, B2w, XN4900 and XN3019 flat screens, respectively. e Cellulose acetate transparent film. f A screen made of B1w and XN4900. g and h, i and j, k and l, m and n, o and p: the two sides of the filament screens S4, S5, S6, S7 and S8, respectively

Fig. 2

A cuboid-shaped wind tunnel (90 × 26 × 26 cm). a Partition frames. b 19 × 19 cm 3D screen. c Mosquito double screen trap. d Mosquito compartment. e Lure compartment. f Mosquito release inlet leading to the mosquito compartment. g Mosquito lure composed of a flat polystyrene flask with a surface area of 150 cm2 filled with warm water (40 °C) and enclosed in a worn sock. h Vents for releasing mosquitoes into the double screen trap. i Sliding lid. j Warm (40 °C) water bottle. k Air pump to push warm air into the test tunnel through warm water. l Temperature and humidity sensor. m Temperature and humidity display. n Warm air inlet

Fig. 3

Diagram of the test tunnel experimental setup. a The location of the released mosquitoes and the lure when the permissive side of the 3D screens was tested. b The location of the released mosquitoes and the lure when the non-permissive side of the 3D screens was tested

Fig. 4

Cylinder-based 3D screens. The left and right panels show the non-permissive and permissive sides of the screens, respectively. a-c Cyl1, Cyl2 and Cyl3 screens with 12, 9 and 7 mm diameter cylinders, respectively

Fig. 5

Filament-based 3D screens. The left and right panels show the permissive and non-permissive sides of the screens, respectively. a S4 screen with a 9 mm long filament and 6 × 11 mm mesh. b S5 screen with a 14 mm long filament and 6 × 11 mm mesh. c S6 screen with a 4 mm long filament and 3 × 5 mm mesh. d S7 screen with a 6 mm long filament and 3 × 5 mm mesh. e S8 screen with a 2 mm long filament and 3 × 4 mm mesh

Fig. 6

Prism-based screens. The left and right panels show the permissive and non-permissive sides of the screens, respectively. a-d screens based on triangular prisms. e Screen based on right triangular prisms. a and c-e screens were made of B2w screening material, b screen was made of B1w screening material. Prisms on a-c screens had 16 cm widths, while those on e had 10 cm widths. The exposed edges of a and c screen prisms had two slits with a length of 5–6 cm each separated by an uncut part of about 1 cm. a and c prisms had 10 and 5 mm wide slits, respectively. e Screen prisms had two slits with a length and width of 10 cm and 5 mm, respectively. Exposed edges of b and d had 11 pores with a 6 mm diameter and 13 pores with a 4 mm diameter, respectively. Prisms on b had two 4 mm long skirts along the exposed edge length creating an arc-shaped edge enclosing the pores at its deepest point. a and d screens had 3 prisms whereas b, c and e had only 2 prisms. The 3 prisms on a had 3 different base widths of 3, 4 and 5 cm from top to bottom

Fig. 7

Cone-based screens. The left and right panels show the non-permissive and permissive sides of the screens, respectively. a-l C01-C12 cone-based screens. a, b, d and i-l Screens with 4 cones. c, e and g Screens with 6 cones. h A screen with 16 cones. d-l Screens with a 40 mm cone base diameters. b and c Screens with 35 mm cone base diameters. h A screen with a 22 mm cone base diameter. a-c Screens with 40 mm cone height diameter. d and e Screens with 30 mm cone height diameter. f, g, i, j, and K Screens with 20 mm cone height diameter. h and l Screen with 15 and 23 mm cone height diameter, respectively. Screen with 2 cones having 40 mm cone base diameters and 2 cones having 35 mm cone base diameters. The apexes of the cones were truncated to create a pore with a 5 mm diameter

Fig. 8

Effect of cone base-to-height ratio on the permissiveness of the permissive side of the cone-based screens