Effects of aqueous and pelletized admixute of Piper nigrum L on the oviposition behavior of Aedes aegypti mosquitoes and its larvicidal-ovicidal activity

ABSTRACT

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.