TITLE: Design and validation of a low-cost sugar-feeder for resource-poor insectaries.
AUTHORS: Zachary Thomas Stavrou - Dowd, Clair Rose, Alvaro Acosta Serrano, Lee R Haines

[DESCRIPTION]
Background
The emergence of insecticide resistance in insects has led researchers to develop new control
tools so that historic gains made in reducing disease transmission are not
lost. Attractive targeted sugar baits (ATSBs) are a vector control tool being
widely trialled to target insects that feed on plant sugars and blood. We
designed a field-friendly, economical and more environmentally responsible sugar
feeder for maintaining mosquito colonies and screening potential ATSB
candidates. 
 
Methods
We simultaneously tested, in both male and female Anopheles gambiae mosquitoes, the effect
of adding three water-soluble medical and food dyes (Allura Red, fluorescein
and tartrazine) to the sugar solution to identify those insects that had
ingested sugar from the feeder. To test feeder efficacy to deliver a toxic
substance, we assessed the killing using boric acid, which kills both male and
female mosquitoes when ingested. Using microscopy techniques compatible with fieldwork,
including the use of a mobile phone camera, we documented the efficacy and
tissue specificity of the dyes on mosquitoes after they were continuously fed dyed
sugar solutions.  
 
Results
The easy-to-construct sugar feeder is an economical option for testing the efficacy
of ATSB components on Anopheles gambiae mosquitoes. Allura Red AC
was the preferred dye as it has low toxicity to mosquitoes and allows the
researcher to quickly visualise the imbibed sugar meal within the abdomen. Feeding
1% fluorescein dye, but not 0.1%, for longer than five days induced systemic
dye distribution, where the mosquito’s wing veins, antennae and legs brightly
fluoresced when examined by a handheld black light torch (395-400nm emission).
 
Discussion 
Developing an affordable sugar feeder to maintain insectary-reared insects and test the
efficacy of ATSB candidates involves designing a dye-labelled sugar bait
station that is of low-toxicity, reusable and easy to construct using
components available in low resource settings such as field stations. 

[BEFORE_START]
Watch video of method

[STEPS]
2. Collect materials required for construction of feeder. See "Materials"

3. Using either your hands or a pair of pliers, unravel the outer loop of a paperclip and twist it into a hanger. 


 

4. Mould the outer loop around the bottom of the tube and leave the inner loop free to construct hanging hook

 
 

5. Tape down the paperclip around the tube using masking tape - 2 or 3 wraps is sufficient.  If hanging outdoors, use waterproof tape.

 

6. Invert the feeder so the hook is now pointing to  the floor and fill feeder with sugar solution.  Adding an insect-safe dye allows sugar levels to be easily monitored.
7. Place a square of fabric tautly over the opening of the feeder and secure in place with an elastic band.  Ensure the fabric used has been previously washed to avoid exposure to insecticides commonly sprayed on textiles during shipment and storage.
8. With thumb placed on top of fabric (to prevent fluid leakage) quickly but gently rotate feeder 180° so hanger is now top positioned.
9. Hang the sugar feeder inside a cage or wherever testing may be taking place
1.