How are male Wolbachia-Aedes aegypti mosquitoes produced? NEA scientist Deng Lu shows CNA how it's done.
Step 1: Egg production
Mosquito eggs are produced in the adult insectary room, and these eggs are used for subsequent male Wolbachia mosquito production.
The room has several mosquito cages, each containing both male and female mosquitoes. At the bottom of the cage are ovipots or egg collection containers that hold several egg strips and stagnant water.
Mosquitoes like the rough texture of the strips and will land on them to lay eggs, said Mr Deng Lu, senior scientist and head of the mosquito production branch.
Step 2: Hatching eggs and counting larvae
A fresh batch of Wolbachia-carrying Aedes mosquito eggs hatch and become larvae within a few hours. They then have to be counted.
There are no turnkey solutions for mosquito production, especially for counting larvae, said Mr Deng. Initially, the team used telecounters and droppers – counting the larvae one by one.
Obviously, the process was not sustainable.
So the team developed its own counting machine, which can count 26,000 larvae in three to five minutes.
Step 3: Seeding the eggs
The next step is the seeding process. Each batch of 26,000 larvae is poured through seeding pods and channelled into individual trays. The trays are then loaded into a high-density rearing rack system.
The environment here has been designed for the comfort of mosquito larvae, with controlled humidity, temperature and airflow.
The team is “very precise” at every step, from mosquito counting and the strict feeding regime to temperature control, said Mr Deng. This is done to achieve optimal mosquito growth in terms of size and quality of yield, he added.
For instance, if there is too much food, the tray containing mosquito larvae will crash. If there is not enough food, the female mosquitoes will be smaller, making it hard to differentiate between the males and the females.
The mosquito larvae stay in the room for about seven days. On day seven, they are harvested for the next process – sex separation.
Step 4: Separating the males from females
After the harvest, the pupae are analysed based on their size to separate the males from the females. This is done using an AI-based scanner which takes a picture of the sample pupae.
The scanner identifies the pupae based on their shoulder size or cephalothorax width – the females are bigger.
The process continues at the sex sorting room, where it takes about three to four hours to generate about 1 to 1.5 million male mosquitoes.
Step 5: Packing and transporting
This is the final step of the production cycle – where the mosquitoes are packed and transported for release.
About 200 male Wolbachia pupae are stored in a black container and packed into crates of 35 containers each. Since the mosquitos are still in the pupa stage, they are left inside for a few days to fully develop.
An NEA field officer then collects the crates and the mosquitoes are sent to various sites for release.
Continue reading...
Step 1: Egg production
Mosquito eggs are produced in the adult insectary room, and these eggs are used for subsequent male Wolbachia mosquito production.
The room has several mosquito cages, each containing both male and female mosquitoes. At the bottom of the cage are ovipots or egg collection containers that hold several egg strips and stagnant water.
Mosquitoes like the rough texture of the strips and will land on them to lay eggs, said Mr Deng Lu, senior scientist and head of the mosquito production branch.
Step 2: Hatching eggs and counting larvae
A fresh batch of Wolbachia-carrying Aedes mosquito eggs hatch and become larvae within a few hours. They then have to be counted.
There are no turnkey solutions for mosquito production, especially for counting larvae, said Mr Deng. Initially, the team used telecounters and droppers – counting the larvae one by one.
Obviously, the process was not sustainable.
So the team developed its own counting machine, which can count 26,000 larvae in three to five minutes.
Step 3: Seeding the eggs
The next step is the seeding process. Each batch of 26,000 larvae is poured through seeding pods and channelled into individual trays. The trays are then loaded into a high-density rearing rack system.
The environment here has been designed for the comfort of mosquito larvae, with controlled humidity, temperature and airflow.
The team is “very precise” at every step, from mosquito counting and the strict feeding regime to temperature control, said Mr Deng. This is done to achieve optimal mosquito growth in terms of size and quality of yield, he added.
For instance, if there is too much food, the tray containing mosquito larvae will crash. If there is not enough food, the female mosquitoes will be smaller, making it hard to differentiate between the males and the females.
The mosquito larvae stay in the room for about seven days. On day seven, they are harvested for the next process – sex separation.
Step 4: Separating the males from females
After the harvest, the pupae are analysed based on their size to separate the males from the females. This is done using an AI-based scanner which takes a picture of the sample pupae.
The scanner identifies the pupae based on their shoulder size or cephalothorax width – the females are bigger.
The process continues at the sex sorting room, where it takes about three to four hours to generate about 1 to 1.5 million male mosquitoes.
Step 5: Packing and transporting
This is the final step of the production cycle – where the mosquitoes are packed and transported for release.
About 200 male Wolbachia pupae are stored in a black container and packed into crates of 35 containers each. Since the mosquitos are still in the pupa stage, they are left inside for a few days to fully develop.
An NEA field officer then collects the crates and the mosquitoes are sent to various sites for release.
Continue reading...