OBJECTIVE: This study was conducted to validate the effectiveness of the ovicidal-larvicidal (OL) trap with the pelletized extracts of Piper nigrum L. in attracting female Aedes aegypti mosquitoes for oviposition and in reducing teh number of larvae hatched, thus preventing the emergence of adult mosquitoes.

METHODS: The OL trap system containing the developed plant-based pellets from Piper nigrum L. was field tested in Marikina and Quezon City. Paired OL traps were installed outdoors in 150 selected houses in each city. The OL trap is composed of a black painted can, a small strip of lawanit (paddle) for oviposition and extracts of Piper nigrum L. as the ovicide-larvicide solution or plain water. Pelletized form of Piper nigrum L. was prepared by grinding the seeds then mixing it with 1% previously cooked starch solution at a ratio of 1:1 followed by extrusion and forming into pellets using a granulator then drying. The number of positive OL traps was recorded. Larval mortality and the Ovitrap Index were also determined.

RESULTS: Four collections were made using the pelletized form in which 2,314 OL traps were collected. The OL traps with the pelletized form showed a 53.2% attraction which is significantly higher than that with water (p-value<0.0001). The percent egg and larval mortality in both cities was recorded at 86.2% while adult emergence is 13.8%. The Ovitrap Index in Marikina was in the range of 53% to 68% while OL traps with water have an Ovitrap Index range of 39% to 65%. In Quezon City, OL traps with the pelletized admixture have an Ovitrap Index range of 35% to 50% while those with water have a range of 31% to 36%.

CONCLUSION: The overall results indicate that the developed OL trap system with Piper nigrum L. is effective in attracting Aedes aegypti mosquitoes. The OL traps with extracts of Piper nigrum L. were also found to be lethal to larvae.

Animal ; Aedes ; Piper Nigrum ; Larva ; Oviposition ; Starch ; Water ; Cities ; Desiccation ; Seeds

OBJECTIVE: The aqueous and pelletized admixture of Piper nigrum L. was evaluated for its oviposition response and larvicidal activity against Aedes aegypti mosquitoes.

METHODS: The aqueous and pelletized extract of Piper nigrum L. was prepared and first tested in the laboratory. Efficiency is evaluated using the mosquito-chamber test. A small-scale field test was also done to determine the oviposition response of the pepper extract to ovicidal-larvicidal (OL) traps. Larvicidal bioassay following the WHO standard protocols with slight modification at different concentrations was performed.

RESULTS: Results of the mosquito chamber test in the laboratory showed that the aqueous solution exhibited an increasing rate of oviposition attraction of female Aedes aegypti to increasing rate of concentration with an average of 70% attraction at 1000 ppm as compared to 30% attraction to OL traps with water alone. The aqueous pepper-based solution and pelletized pepper solution at 1000 and 2000 ppm are considered attractants to Aedes mosquitoes. Both solutions have oviposition activity index (OAI) of > +0.3. It was also field tested on the 10 buildings within the Department of Science and Technology (DOST) compound. Results showed an oviposition ratio two times better in both the 1000 ppm concentration of the aqueous pepper-based solution and pelletized pepper solution as compared to the control. The positive ovitrap index was in the range of 78%-84% for both the aqueous pepper-based and pelletized pepper against water which is 70.0%. Larvicidal activity of the aqueous pepper-based solution against 3rd larval instars of Aedes aegypti at increasing dosages from 75mg/1 to 600 mg/I had an LCso of 127 mg/I and 395 mg/I for LC90 The LCso for the solution with pelletized pepper at the same dosing concentration is 117 mg/I with LC90 of 285 mg/1. The results also showed that these can be used to control larval instars of the Aedes aegypti mosquitoes.

CONCLUSION: The overall results indicate that the aqueous and pelletized extracts of Piper nigrum L. are effective in attracting the Aedes aegypti mosquitoes for oviposition and exhibit a larvicidal activity.

Animal ; Aedes ; Piper Nigrum ; Larva ; Oviposition ; Water ; Biological Assay