title: Oviposition-stimulant and ovicidal activities of Moringa oleifera lectin on Aedes aegypti.
abstract: BACKGROUND
  Natural insecticides against the vector mosquito Aedes aegypti have been the object of research due to their high level of eco-safety. The water-soluble Moringa oleifera lectin (WSMoL) is a larvicidal agent against A. aegypti. This work reports the effects of WSMoL on oviposition and egg hatching of A. aegypti.
  
  
  RESULTS
  WSMoL crude preparations (seed extract and 0-60 protein fraction), at 0.1 mg/mL protein concentration, did not affect oviposition, while A. aegypti gravid females laid their eggs preferentially (73%) in vessels containing isolated WSMoL (0.1 mg/mL), compared with vessels containing only distilled water (control). Volatile compounds were not detected in WSMoL preparation. The hatchability of fresh eggs deposited in the solutions in the oviposition assay was evaluated. The numbers of hatched larvae in seed extract, 0-60 protein fraction and WSMoL were 45 ± 8.7 %, 20 ± 11 % and 55 ± 7.5 %, respectively, significantly (p<0.05) lower than in controls containing only distilled water (75-95%). Embryos were visualized inside fresh control eggs, but not within eggs that were laid and maintained in WSMoL solution. Ovicidal activity was also assessed using stored A. aegypti eggs. The protein concentrations able to reduce the hatching rate by 50% (EC50) were 0.32, 0.16 and 0.1 mg/mL for seed extract, 0-60 protein fraction and WSMoL, respectively. The absence of hatching of stored eggs treated with WSMoL at 0.3 mg/mL (EC99) after transfer to medium without lectin indicates that embryos within the eggs were killed by WSMoL. The reduction in hatching rate of A. aegypti was not linked to decrease in bacteria population.
  
  
  CONCLUSIONS
  WSMoL acted both as a chemical stimulant cue for ovipositing females and ovicidal agent at a given concentration. The oviposition-stimulant and ovicidal activities, combined with the previously reported larvicidal activity, make WSMoL a very interesting candidate in integrated A. aegypti control.
authors.affiliation: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Cidade Universitária, Recife, Pernambuco, Brazil.
authors.forename: Nataly Diniz de Lima
authors.initials: ND
authors.lastname: Santos
authors.forename: Kézia Santana
authors.initials: KS
authors.lastname: de Moura
authors.forename: Thiago Henrique
authors.initials: TH
authors.lastname: Napoleão
authors.forename: Geanne Karla Novais
authors.initials: GK
authors.lastname: Santos
authors.forename: Luana Cassandra Breitenbach Barroso
authors.initials: LC
authors.lastname: Coelho
authors.forename: Daniela Maria do Amaral Ferraz
authors.initials: DM
authors.lastname: Navarro
authors.forename: Patrícia Maria Guedes
authors.initials: PM
authors.lastname: Paiva
mesh_terms: D000330:Aedes / Q000502:physiology*; D000818:Animals; D005260:Female; D037102:Lectins / Q000302:isolation & purification / Q000494:pharmacology*; D029588:Moringa oleifera / Q000737:chemistry*; D010058:Oviposition / Q000187:drug effects*
chemical_list: D037102:Lectins