New Delhi: How about a marker pen with red chilly or turmeric ink? Or a mosquito repellent produced from papaya leaves? Budding scientists from Maharashtra and Gujarat have come up with these products, receiving recognition at an international science fair.

"Increasing cases of malaria and dengue fever led us to find a solution. The initial idea was to find an eco-friendly method to control mosquitoes," said Divya Venkatraman, a student of Modern English School, Mumbai.

Venkatraman and her classmate Neha Kulkarni have developed an extract from the leaves of papaya and tested it at different stages of mosquito breeding. They studied the efficacies of the extract for several months and found that "the mortality rate of mosquitoes was 86 percent".

"We collected papaya leaves, crushed them to make an extract, diluted it in water and studied its effect on mosquitoes in different stages," Kulkarni told IANS.

Venkatraman and Kulkarni have returned after showcasing their innovations at the Intel International Science and Engineering Fair (IISEF) in the US last month.

They bagged the third prize beating nearly 1,500 young innovators from across the world. Indian Science and Technology Minister Kapil Sibal has also given them certificates of recognition for excellent scientific temper.

Venkatraman said their product is completely bio-natural, easily available and cost effective. It doesn't cause any harm to the soil, plants and human beings.

"It's also environment-friendly, has no biological hazards and the rural population can immensely benefit from it," she said.

Similarly, another pair of budding scientists from the S.G. Dholakiya Memorial High School in Rajkot, Gujarat, has produced marker pen ink from chilly (red ink), turmeric (yellow), carrot (saffron) and even rose petals (pink).

"First, all different types of coloured vegetables are taken and crushed separately. This solution is boiled at 100 degrees Celsius for nearly 20 minutes. It is kept for self-cooling and after nearly an hour, the dye is prepared," said Pooja Dholakiya.

"Kerosene is added in different proportions to the dye. Then 0.5 cm diameter cotton cording is taken and poured into the dye. After about one hour, people can use it as marker pen," explained Dholakiya's classmate Ridhi Dasani.

They too represented India at IISEF 2008. As a team they got a $1,000 award at the fair.

"It's heartening to see that budding scientists are going eco-friendly. This is a good sign for both science and new innovations," Sibal said. IANS