NJMCA Mosquito Rearing Kit

MOSQUITO REARING  (Note: *Superscript refers to a possible question asked by a student and its answer. Questions and answers are at the end of this paper.)

Materials:

1. Mosquito eggs on a strip of paper (The mosquito species is Aedes atropalpus)¹
2. Brewer's Yeast (Glycine envelope) 1
3. Food for mosquito larvae. (Glycine envelope) 2
4. Pipette (sucker bulb).
5. Popsicle stick
6. Rubber bands
7. Screening for glass jar
8. Materials you will need to provide: pan, preferably glass; glass jar and a Dixie cup.

Eggs: Aedes ² mosquitoes lay their eggs on damp surfaces ³. For the experiment, you are provided with eggs of Aedes atropalpus that were laid by females on damp filter paper. The eggs appear like tiny black specks on the filter paper. Eggs of Aedes mosquitoes have the ability to withstand dry conditions. In nature, they require a dry weather period before they can hatch. Such eggs hatch after a rain or flooding, etc. Mosquito eggs are sensitive to chlorine in tap water. To rear your larvae you will have to de-chlorinate tap water by leaving it stand in your glass jar for at least 24 hours. Aedes eggs also hatch better in deoxygenated water. To make deoxygenated water add the Brewer's yeast to the water you de-chlorinated and leave it overnight with the top of the jar tightly closed.

Next morning add the piece of filter paper containing the eggs to the water. Be sure the filter paper is totally submerged and the eggs are on the upper side of the paper. Eggs will start hatching within 20-30 minutes. If the eggs do not hatch, remove the filter paper with the eggs, allow the paper to dry and submerge again. After 2 hours empty the contents of the jar into the pan. Fill the pan with aged tap water. Add food, very little, to the pan.

Larval Rearing: Mosquito larvae go through 4 larval molts before they change into pupae, the non-feeding stage in the life cycle of the mosquito. You will observe that larvae will molt as they grow into the next instar or stage. Add a little food4 every other day and add aged water to keep the pan full. Occasionally a surface film, scum, will form on the surface of the water, skim this off with a piece of paper towel.

1. First instar larvae will molt to the 2nd instar in 2-3 days ⁵. They may also continue to molt the next day. Daily skim the water surface of your rearing pan with a paper towel to remove the scum. Aedes larvae use an air tube to breathe air. The air tube works like a snorkel and is present at the posterior end of the larva. Not removing the surface scum will suffocate the larvae.
2. The 2nd instar larvae will molt to the 3rd instar 3 -4 days after hatching. You will be able to show the molted skins to your students.
3. On the 4th to 5th day, the larvae will molt to the 4th instar. At this stage they are much larger in size and you can observe them feeding both at the bottom of the pan and near the surface of the water. Mosquito larvae use their mouth brushes to constantly draw food particles to their mouths.
4. On the 7th to 8th day after egg hatching, 4th instar larvae will molt to pupae. The pupae are round in shape as opposed to the long shape of the larvae. The pupae tumble actively up and down in the water. They have a breathing apparatus that is located on top of their head. The breathing apparatus is called a trumpet. When pupae appear stop adding food, as pupae do not eat.
5. Fill the jar ¼ full with aged tap water and transfer a few pupae into it. Place the netting on the top of the jar. The pupae that appear first are male mosquitoes. Male mosquitoes have bushy antennae. Female pupae appear later. Females do not have bushy antennae and are the ones that bite. The adults will emerge in 2-3 days.
6. You can kill the pupae you don't want by throwing them on the ground. You can kill the adults by freezing them.
7. If you would like to keep the adults alive for a while place a small piece of cotton soaked in sugar water on the top of the netting or a slice of apple inside the container. The mosquitoes will feed on the sugar water and/or apple slice. Mosquitoes do not take blood to survive. They use blood strictly for the development of their eggs. You can observe the complete mosquito life cycle within 10-12 days at 75°F to 80°F.

Additional information pertaining to this mosquito rearing kit should be addressed to:

Possible questions students may ask and the answers.

1. Why do we use this species of mosquito? It is a mosquito native to New Jersey. It is not connected to the transmission of a disease. There are more than 60 different species of mosquitoes in New Jersey.

2. Are there other types of mosquitoes than Aedes? Yes, there are. Aedes mosquitoes are one genus of mosquito. New Jersey has 10 genera of mosquitoes. The most common ones are: Aedes, Culex, Psorophora and Anopheles.

3. What kind of damp surface would this mosquito use in nature? The female would deposit its eggs on mud in any depression that could become flooded by rain.

4. What is the food? We have given you finely ground up dog food. In nature mosquito larvae would feed on one celled organisms, bacteria, protozoa and algae.

5. Why are our larvae taking longer that 2 to 3 days to molt? The amount of time needed to molt is related to the temperature of the water. This handout assumes a water temperature of 75° F to 80°F. Cooler temperatures will slow the mosquito's development and lengthen their life cycle.

6. Why do I have to skim the surface film off the top of the water? Mosquito larvae and pupae breath air just like we do. They do not have gills like fish, where they can get oxygen out of the water. The surface film can prevent the immature mosquitoes from breathing. It would be like you putting a piece of plastic over your mouth and nose and trying to breath.