Effect of Moringa oleifera lectin on development and mortality of Aedes aegypti larvae

Abstract

Aedes aegypti larvae have developed tolerance to many insecticides used for mosquito control. Moringa oleifera seeds contain a water-soluble lectin (WSMoL) and this paper reports the effect of M. oleifera seed extracts (MoE(1-15)) and WSMoL on development and survival of A. aegypti larvae. WSMoL peptide from in-gel trypsin digestion is also described. MoE(1-15) showed hemagglutinating activity and WSMoL had similarity with flocculating proteins from M. oleifera seeds. MoE(1) and MoE(3) delayed larval development which stopped in the third instar (L3) in MoE(6) and MoE(15). Significant (p<0.0001) larval mortality was only detected in MoE(15). Native WSMoL showed larvicidal activity (LC(50) 0.197 mg mL(-1)) and heated lectin, without hemagglutinating activity, did not kill fourth instar (L4) larvae. Optical microscopy showed that live L4 from MoE(1) presented underlying epithelium, increased gut lumen and hypertrophic segments; dead L4 from WSMoL were absent of underlying epithelium, had increased gut lumen and hypertrophic segments. The presence of hemagglutinating activity in the extracts suggests that soluble lectin promotes the delay of larval development and mortality; furthermore, the absence of larvicidal activity in heat-denatured WSMoL strengthens the involvement of lectin in this activity mechanism.

Lectin, hemolysin and protease inhibitors in seed fractions with ovicidal activity against Haemonchus contortus

“…These results suggest that the active molecule is water soluble and has a low molecular weight (< 12 kDa). Considering that hemagglutination activity was observed in this fraction (Table 1), a strong candidate for ovicidal activity is a flocculation protein from M. oleifera with a molecular mass of 6.5 kDa (GASSENSCHMIDT et al, 1995;NDABIGENGESERE et al, 1995), which has reportedly shown larvicidal activity (COELHO et al, 2009) andovicidal activity against A. aegypti (SANTOS et al, 2012). However, the CENR fraction from M. oleifera showed other protein activities that cannot be ignored, such as hemolysin and protease inhibitors (Table 1).…”

Safety and Efficacy of Moringa oleifera Lamarck (1785) — Therapeutic and Toxicological Properties

“…At work [100] has associated this larvicidal potential with flocculating proteins such as lectins found in the seeds, which delay and/or impede the larvae development of the A. aegypti mosquito and other insects, especially extending larval early stages (L1 and L2). Lectin treatedlarvae in IV instar presented morphological changes as enlarged intestinal lumen and hypertrophy or loss of the luminal epithelium.…”

Insecticide Activity of Lectins and Secondary Metabolites

“…Lectins have deleterious effects against larvae, developing stages and mature forms of insects from orders Coleoptera, Diptera, Hemiptera, Homoptera, Hymenoptera, Isoptera, Lepidoptera and Neuroptera (Murdock et al, 1990;Eisemann et al, 1994;Powell et al, 1995;Zhu-Salzman et al, 1998;Bandyopadhyay et al, 2001;Isidro et al, 2001;Hogervorst et al, 2006;Kaur et al, 2006;Coelho et al, 2007;Macedo et al, 2007;Fitches et al, 2008;Sá et al, 2008;Coelho et al, 2009;Sá et al, 2009c;Silva et al, 2009;Napoleão et al, 2011;Souza et al, 2011b). Insecticide activity of lectin is generally evaluated by bioassays that incorporate the lectin into artificial diets offered to insects, with insects dying from nutritional deprivation.…”

“…Santos et al (2005) revealed the presence of water-soluble M. oleifera lectin (WSMoL) in M. oleifera seed extracts by detection of hemmaglutinating activity. The procedure for WSMoL isolation was defined by Coelho et al (2009) and included the steps of protein extraction with water, precipitation of lectin with ammonium sulfate (60% saturation) and chromatography of precipitated fraction on a chitin column. WSMoL agglutinated human and rabbit erythrocytes in a broad pH range of 4.5 to 9.5 and when kept at 100 ºC for 5 h plus incubation overnight at 37 ºC.…”