Anopheles gambiae Larval Development and Toxicity抯 Reduction of Conventional Agriculture Insecticides in the Laboratory Conditions

Background: Vector control of Malaria is mainly made by using impregnated bed nets and insecticides pulverizations indoor or/and outdoor. Besides, appearance and development of resistance抯 phenomenon among mosquito populations to insecticides, constitute a significant obstacle this fighting. Aims: To highlighting a neutralization phenomenon of three insecticides (methyl-parathion, dimethoate and cypermethrin) during development of the Anopheles gambiae s.s. larvae. Methodology: Two setups followed one after the other were designed. In setup 1, four concentrations (with four replicates each) were freshly prepared and independently received a first batch of 100 first instars An. gambiae s.s. After emergence of adults from this first batch, the same test media were simply filtered and received a second batch of first instars larvae to make setup 2. Three endpoints were measured in this study: the duration of larval phase, the larval mortality, and the size of adults. Results: The development duration and mortality of larvae decreased significantly at setup 2 with cypermethrin and methyl-parathion. Thus, the duration of larval stage decreased from 10.18 days at setup 1 to 7.84 days at setup 2 for 0.010 礸/l (highest concentration) with cypermethrin and from 10.20 days at setup 1 to 8.27 days at setup 2 for 0.144 礸/l (highest concentration) with methyl-parathion. The larval mortality dropped from 79.32 % at setup 1 to 12.00 % at setup 2 for the highest concentration of cypermethrin and from 76.42 % at setup 1 to 12.50 % at setup 2 for the highest concentration of methyl-parathion. While adults size significantly increased in setup 2. For males, wing抯 length increased from 3.28 mm at setup 1 to 3.49 mm at setup 2 for the highest concentration of cypermethrin, from 3.31 mm at setup 1 to 3.49 mm at setup 2 for the highest concentration of methyl-parathion. In female, wing抯 length increased from 3.52 mm at setup 1 to 3.68 mm at setup 2 for the highest concentration of cypermethrin, from 3.49 mm at setup 1 to 3.68 mm at setup 2 for the highest concentration of methyl-parathion. Conclusion: This work shows that mosquito larvae, especially An. gambiae are able to modify breeding medium to improve its fitness during their development.

The ParasightTMF-Test : sensitivity; specificity and possible usefulness in common practice : a review

This article deals with the ParasightTMF-Test which is a chromatographic immuno assay that detects histidine rich protein II (HRP II) antigen of Plasmodium in whole blood

Evaluation de l'activite limitant la transmission homme-vecteur du paludisme dans le plasma des porteurs de gametocytes au Cameroun

Une souche d'anopheles gambiae d'elevage a ete infectee experimentalement avec des gametocytes de plasmodium falciparum issus de 65 patients du Cameroun. Une comparaison a ete faite entre les infections avec le sang contenant le plasma des porteurs de gametocytes eux-memes et celles realisees avec le sang dont le plasma avait ete remplace par celui d'un donneur sans antecedant palustre et donc non immun. Un taux d'infections des moustiques plus faible a ete observe dans 50 des 65 echantillons de sang contenant le plasma des porteurs. Le taux moyen global de reduction du pour centage de moustiques infestes a ete de 36;8 pour cent; et la transmission a ete significativement bloquee dans 3 experimentations. Ceci indique que dans les populations residant en zone d'endemie palustre; les facteurs du plasma peuvent reduire la capacite des porteurs de gametocytes a transmettre le plasmodium aux moustiques

Infections experimentales de anopheles gambiae avec differentes souches de plasmodium falciparum issu de porteurs de gametocytes naturellement infectes au Cameroun: facteurs influencant l'infection des moustiques

L'activite des porteurs de gametocytes de plasmodium falciparum presentant des symptomes palustres dans la ville de Yaounde pour une souche d'anopheles gambiae a ete evaluee et les facteurs susceptibles d'influencer la reussite des infections experimentales ont ete recherches. 139 infections experimentales avec le sang de differents porteurs de gametocytes ont ete effectuees. Apres dissection d'au moins 20 moustiques par experimentation; 86 (62 pour cent) porteurs de gametocytes ont donne au moins un moustique positif en oocyste. Parmi les infections reussies; le pour centage moyen de moustiques infectes a ete de 18;60 pour cent et la moyenne d'oocystes par estomac infeste de 2;56. La densite gametocytaire seule a ete identifiee comme facteur determinant le succes et le taux d'infection des moustiques. Aucune influence significative n'a ete trouvee pour le sexe et l'age des porteurs de gametocytes; la temperature corporelle; la presence et la densite des stades erythrocytaires asexues; le groupe sanguin; le facteur rhesus et la prise d'antimalariques (chloroquine et amodiaquine)