Aedes Mosquito Survey Method

To collect adult Aedes aegypti mosquitoes from house to house, trained insect collectors follow specific methods with attention to timing and mosquito behavior.

A) Ideal Method

1. Use battery-powered backpack aspirators or mechanical aspirators to catch resting adult mosquitoes inside houses, especially in dark, cool places like under furniture, closets, curtains, walls, ceilings, shaded areas, and bathrooms.
2. Collect mosquitoes by slowly moving the aspirators near resting sites to avoid startling them.
3. Conduct pyrethrum spray catches (PSC) indoors where a pyrethrum insecticide is sprayed, and knocked-down mosquitoes are collected on a white sheet.
4. Use traps like BG-sentinel traps placed near human dwellings to collect host-seeking females.

OR

Insect collectors should collect mosquitoes daily at 10 houses. Spend 15 minutes at each house, collecting mosquitoes for a total duration of 2:30 hours.
Store the collected mosquitoes in the glass test tubes with a cotton lint bag. The cotton lint bag should be moistened in summer and kept dry during winter and the rainy season.
Write the house number from which the mosquitoes were collected on the test tube, and record the same information in the daily logbook.
In the laboratory, identify the sex (male or female) and species of collected mosquitoes.
Calculate the mosquito density for that particular day and village, and similarly, calculate the weekly mosquito density.
Dissect the female mosquitoes to determine the infection rate.
If the infection rate is high, immediately implement preventive measures.

B) Ideal Timing

Early mornings around 6:30 AM to 9:30 AM and late afternoons around 5:00 to 7:00 PM are ideal since Aedes aegypti is most active during these hours.
Indoor collections can be done any time but are often scheduled when residents are available and mosquitoes’ resting behavior peaks.

C) Identification

1. Aedes aegypti is the principle vector of dengue fever, with Aedes albopictus being the secondary vector.
2. It is a small, black mosquito with white stripes and is approximately 5 mm in size. It is also known as the tiger mosquito.
3. Morphological keys distinguish Aedes aegypti by its black body with white lyre-shaped thoracic markings, silver-white leg bands, and proboscis length shorter than clypeus; females have a wing length averaging 2.7 mm. Insect collectors confirm species by examining these traits under magnification post-collection, separating them from Aedes albopictus, which has a white dorsal stripe on the thorax. and Aedes vittatus, which has a blackish-brown scutum with six silvery white spots arranged in three distinct pairs on the thorax.

D) Adult Mosquito Density

The density of adult Aedes aegypti can be calculated as

This gives the average number of adult Aedes mosq. per house.

These methods ensure representative sampling of the indoor adult mosquito population to guide vector control interventions effectively. Proper training of collectors ensures safety and accurate data collection indoors.

Example

• If an insect collector inspects 20 houses & collects a total of 100 adult Aedes aegypti mosquitoes, the average density per house will be

• If an insect collector inspects 10 houses & collects a total of 100 adult Aedes aegypti (male and female) mosquitoes during 2 hours and 30 minutes, the density of mosquitoes per man-hour will be:
  

Feeding Habit of Aedes Mosquito

1. Day biter (prefers to bite during daytime)
2. Mainly feeds on human beings in domestic and peridomestic situations.
3. Bites repeatedly

Resting Habit

Rests in the domestic and peridomestic situations.
Rests in the dark corners of the houses, on hanging objects like clothes and umbrellas, under the furniture, etc.

Breeding Habit

1. The Aedes aegypti mosquito breeds in any type of man-made container or storage container having even a small quantity of water.
2. Eggs of Aedes aegypti can survive without water for up to one to two years.
3. An egg of Aedes aegypti, once infected with the DEN virus, remains infected for its whole life and also transmits the virus through its eggs and next progeny (trans-ovarian transmission).

Favoured Breeding Places

• Desert coolers, drums, jars, pots, and buckets.
• Flower vases, plant saucers, overhead tanks, and cisterns.
• Bottles, tins, tires, and roof gutters.
• Refrigerator drip pans, cement blocks.
• Bamboo stumps, coconut shells, tree holes, and many more places where rainwater collects or is stored.