New tech that can count mosquito larvae in shorter time used in mosquito suppression study

Orinno Technology co-founder, Dr David Du, with the larvae counter, which has been helping with the rearing of male Wolbachia-Aedes mosquitoes.
Orinno Technology co-founder, Dr David Du, with the larvae counter, which has been helping with the rearing of male Wolbachia-Aedes mosquitoes.PHOTO: COURTESY OF DR DAVID DU

SINGAPORE - As part of an ongoing field study into curbing dengue transmissions here, researchers have been producing their own Aedes aegypti mosquitoes and infecting them with the Wolbachia bacteria so they cannot reproduce.

But the process was laborious at the start, with researchers having to count each lava individually as they filled a tray of water with 4,000 mosquito larvae.

Local start-up Orinno Technology then created a device in 2016 which reduced the two-hour process to just three minutes.

Called the larvae counter, it counts mosquito larvae 30 times faster than previous manual methods. This has helped to increase the production rate and quality of male Wolbachia-Aedes mosquitoes reared for research.

The field study into a novel method to suppress Aedes aegypti mosquitoes in Singapore has delivered promising results since it started in 2016.

In the study, male Aedes aegypti mosquitoes, which neither bite humans nor transmit disease, are artificially infected with Wolbachia bacteria.When they are released and mate with females which are not infected, the resulting eggs do not hatch.

Orinno Technology created the larvae counter in collaboration with the National Environment Agency's (NEA) Environmental Health Institute.It is working on two other devices with the institute - a pupae counter and dispenser, and an automated sex sorter that can separate male and female mosquitoes.

The larvae counter, which has been used for the past two years, has allowed researchers to produce enough male mosquitoes for the first phase of Project Wolbachia-Singapore field study, said NEA.

The results of this phase , released in December last year (2017), showed it was successful in suppressing half the targeted Aedes aegypti population observed in three sites.

The ongoing second phase of the study will involve more housing blocks in two of the three sites previously studied. Also, about one to six mosquitoes will be released per person each week, up from one to three mosquitoes previously.

Speaking to The Straits Times, Orinno Technology's co-founder, Dr David Du, 35, said:"The automatic tools will help to increase the number of mosquitoes reared, so it can be deployed on a large enough scale for the study."

All these devices will not only help to save manpower and cost, but will ensure the consistency and quality of the male mosquitoes produced, said Dr Du who has a Phd in engineering.

He said that one of the challenges in rearing the mosquitoes was ensuring that the larvae grow in a uniform way so sorting of the male and female pupae can be done more accurately. Male mosquito pupae are smaller than female pupae, so uniformity for each sex will help the sorting process.

"It's important that the amount of nutrients and water is uniform for each batch, and the larvae counter will also ensure the population number in each dish is the same." He believes the devices are not just beneficial to public health in Singapore, but the whole world.

"If this strategy is a success, I believe it will create a lot of value especially for people in developing countries. It's meaningful that we can contribute our knowledge and make this project successful," said Dr Du.

"Besides, I always get bitten by mosquitoes, and that's one personal reason for me."

Dr Du said after a presentation at the ASEAN Dengue Day Workshop in early June in Singapore, representatives from countries in attendance showed an interest in the devices created by Orinno Technology.

"Many countries are adopting similar projects, and we are exploring possible collaboration opportunities," he added. Similar field studies have been done in China, Australia and Thailand, but Singapore is the first to adopt its tools, said Dr Du.

The two-day conference, which was held in the lead up to ASEAN Dengue Day on Friday (June 15), saw a total of 150 participants from 24 countries, comprising researchers, pest control industry experts, policymakers, and the product development industry.

There were 2,772 dengue cases reported here for the whole of last year (2017). In comparison, during Singapore's worst dengue epidemic in 2013, more than 22,000 people were infected.