title: Application of Polovodova's method for the determination of physiological age and relationship between the level of parity and infectivity of Plasmodium falciparum in Anopheles gambiae s.s, south-eastern Benin.
abstract: BACKGROUND
  Polovodova method based on counting follicular dilatations estimates the number of egg-laying in mosquitoes. However, some researchers doubt the reliability of this method because of the absence of multiple dilatations in vectors after many gonotrophic cycles. It is in this context of controversy that our study was carried out to evaluate the importance of follicular dilatations in the determination of parity levels in An. gambiae s.s. Moreover, the application of this method allowed us to clarify the evolution of vectors' infectivity to P. falciparum according to their parity level.
  
  
  METHODS
  We used two techniques to determine the parity level in An. gambiae s.s. We used two batches of wild strain mosquitoes reproduced after a known number of egg-laying in laboratory. The first batch was submitted to oil injection in the ovaries using a micropipette. In the same way, the classic technique of ovaries dilaceration (a technique based on the Polovodova method) was applied to the second batch. In order to assess relationship between parity level and mosquitoes' infectivity, Polovodova method was applied on vectors collected on humans. Finally, Heads and thoraces of these vectors were individually analyzed for P. falciparum antigen detection using an ELISA assay.
  
  
  RESULTS
  In the first batch including 50 female mosquitoes "never laid", 50 "laid once", 50 "laid twice" and 48 "three times", oil injection technique revealed 42 nulliparous, 44 uniparous, 46 biparous and 44 triparous respectively. Overall, Polovodova method was effective using oil injection technique (p > 0.05). On the other hand, in the second batch that has a similar number of laying to the first batch, the application of Polovodova method through classical technique of ovaries dilaceration was ineffective with multiparous females (p < 0.05). Moreover, probability of vector infectivity increased with the number of egg-laying (p < 0.0001).
  
  
  CONCLUSIONS
  Our results revealed that the Polovodova method is reliable for estimating the number of egg-laying in Anopheles gambiae s.s. using oil injection technique in the ovaries. The study has also showed an increased likelihood of infectivity in vectors according to the number of egg-laying.
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. rodrigue.anagonou@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. rodrigue.anagonou@yahoo.fr.
authors.forename: Rodrigue
authors.initials: R
authors.lastname: Anagonou
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. rofargossa@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. rofargossa@yahoo.fr.
authors.forename: Fiacre
authors.initials: F
authors.lastname: Agossa
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. roseric_2000@yahoo.fr.|University of Wisconsin, Milwaukee, WI, USA. roseric_2000@yahoo.fr.
authors.forename: Roseric
authors.initials: R
authors.lastname: Azondékon
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. agbogan.marc@gmail.com.
authors.forename: Marc
authors.initials: M
authors.lastname: Agbogan
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. fredook15@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. fredook15@yahoo.fr.
authors.forename: Fréderic
authors.initials: F
authors.lastname: Oké-Agbo
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. amerusangel@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. amerusangel@yahoo.fr.
authors.forename: Virgile
authors.initials: V
authors.lastname: Gnanguenon
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. kefilathbadirou@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. kefilathbadirou@yahoo.fr.
authors.forename: Kèfilath
authors.initials: K
authors.lastname: Badirou
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. ramloving@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. ramloving@yahoo.fr.
authors.forename: Ramziath
authors.initials: R
authors.lastname: Agbanrin-Youssouf
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. ermyon2012@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. ermyon2012@yahoo.fr.
authors.forename: Roseline
authors.initials: R
authors.lastname: Attolou
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. pagergil@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. pagergil@yahoo.fr.
authors.forename: Gil Germain
authors.initials: GG
authors.lastname: Padonou
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. sart52005@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. sart52005@yahoo.fr.
authors.forename: Arthur
authors.initials: A
authors.lastname: Sovi
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. ossraz@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. ossraz@yahoo.fr.
authors.forename: Razaki
authors.initials: R
authors.lastname: Ossè
authors.affiliation: Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Benin. akogbetom@yahoo.fr.|Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Calavi, Bénin. akogbetom@yahoo.fr.
authors.forename: Martin
authors.initials: M
authors.lastname: Akogbéto
mesh_terms: D000818:Animals; D000852:Anopheles / Q000502:physiology*; D001541:Benin / Q000453:epidemiology; D005260:Female; D005843:Geography; D006801:Humans; D007303:Insect Vectors / Q000502:physiology*; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000469:parasitology*; D008297:Male; D010058:Oviposition; D010063:Ovum; D010298:Parity; D010963:Plasmodium falciparum / Q000502:physiology*; D015203:Reproducibility of Results; D012098:Reproduction