UPLB looks into potential of waterbug as dengue mosquito predator

by: Jane Klariz M. Sadie

Could water bug be the answer to the country’s rising dengue cases?

Dr. Pio A. Javier of the College of Agriculture, University of the Philippines Los Banos is looking into the potential of water bug as a possible predator of dengue carrying mosquitoes.

Water bug or Diplonycus rusticus is a flat insect usually found in rice fields. Mosquito larvae and snails served as their food.

Based on Dr. Javier’s research, the adult water bug could eat about 89 to 99 full grown larvae of mosquitoes per day.

His curiosity about water bug started in his class in Biological Control, where he collected biological control agents in the agro ecosystem to be shown to his students. The rising dengue cases in the country triggered him to test the potential of the water bug to reduce the population of dengue-carrying mosquitoes.

His study about water bug is not the first.

Dr. Javier shared that another species of water bug, Diplonicus indicus, against mosquitoes had been studied in India.

In the studies, two water bugs were released in every mosquito-infested tire and results showed that it can reduce 95-99 percent pupal density by 95-98 percent. This means that the release of water bug could be a novel approach in the control of dengue-carrying mosquitoes.

Many dengue prevention methods have been introduced in the country, and an example is the Ovicidal-Larvicidal (OL) Trap, promoted by the Department of Science and Technology (DOST). In this method, a cup filled with the solution that can kill mosquito larvae is placed on dengue infested areas. However, if the solution was not replaced on time, instead of reducing dengue-carrying mosquito population, the solution can increase the population.

Unlike the OL Trap, water bug does not need much maintenance. According to Dr. Javier, the advantages of water bug are that it is natural, harmless, and it is not hard to maintain. It is readily available, because the water bug tends to reproduce faster and more if it is always fed. Most importantly, the insect target the eggs or wrigglers, rather than the adult mosquitoes which most of the prevention methods do.

As he suggested, “Dapat ang control ay habang wrigglers pa lang. ‘Yung wrigglers, hindi pa iyon nakakapangagat. Once na naging adult siya, I think delikado na. ‘Pag mas mababa ang population ng wrigglers, mas mababa din ang population ng adult, at mas kaka-unti ang makakapagtransmit ng virus.”

He also recommended that the release of the water bug should be during dry season, so the mosquitoes do not have any other place to lay their eggs. However, Dr. Javier clarified that his study about the potential of water bug in countering the growth of dengue-carrying mosquitoes is still in its early phase.

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