Effect of gamma irradiation of Moringa oleifera seed lectin on its larvicidal, ovicidal, and oviposition-stimulant activities against Aedes aegypti

• Published in: South African journal of botany 2020-03, Vol.129, p.3-8
• Main Authors: Santos, N.D.L., Napoleão, T.H., Benevides, C.A., Albuquerque, L.P., Pontual, E.V., Oliveira, A.P.S., Coelho, L.C.B.B., Navarro, D.M.A.F., Paiva, P.M.G.
• Format: Article
• Language: English
• Subjects: Dengue mosquito; Larvicidal effect; Lectin irradiation; Moringa oleifera; Ovicidal activity; Oviposition-stimulant
• ISSN: 0254-6299; 1727-9321
• DOI: 10.1016/j.sajb.2018.05.001

The water-soluble Moringa oleifera lectin (WSMoL) exhibits larvicidal, ovicidal, and oviposition-stimulant effects on Aedes aegypti. Here, we evaluated the influence of gamma irradiation on the activity of WSMoL against A. aegypti. Irradiation with 10mGy and 10Gy did not result in the loss of protein molecules; however, irradiated samples presented a distinct profile on gel filtration chromatography. Bis-ANS probe fluorescence was similar when incubated with non-irradiated and 10mGy-irradiated samples, but less intense fluorescence was observed when incubated with 10Gy-irradiated WSMoL, indicating the exposure of lectin hydrophobic pockets to water. Irradiation of WSMoL with 10mGy potentiated its larvicidal and ovicidal activities, while irradiated WSMoL with 10Gy did not affect the survival of larvae and eggs. The stimulation of oviposition by WSMoL was not observed with irradiated samples. Nevertheless, the hatching rate of eggs laid on vessels containing 10mGy-irradiated lectin (37%) was lower than that in vessels containing non-irradiated WSMoL (59%). In conclusion, a low dose of gamma irradiation (10mGy) can be used to improve the deleterious effects of WSMoL on A. aegypti larvae and eggs, while a higher dose (10Gy) was found to impair the insecticidal effects on this mosquito. These changes are probably linked to conformational changes in the structure of WSMoL. •The lectin WSMoL was exposed to gamma radiation at 10mGy and 10Gy.•There was no loss of protein molecules but conformational change was detected at 10Gy.•Irradiation of WSMoL with 10mGy potentialized larvicidal and ovicidal activities on A. aegypti.•Hatching of eggs laid on 10mGy-irradiated lectin solution was lower than in non-irradiated WSMoL.