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Water Quality and Anopheles gambiae Larval Tolerance to Pyrethroids in the Cities of Douala and Yaoundé (Cameroon).

Tene Fossog B, Kopya E, Ndo C, Menze-Djantio B, Costantini C, Njiokou F, Awono-Ambene P, Antonio-Nkondjio C - J Trop Med (2012)

Bottom Line: No significant difference was observed between polluted and nonpolluted sites.A low but significant correlation was detected between physicochemical parameters and larval insecticide tolerance.Dissolved oxygen (r = +0.466; P < 0.0001) and ammonia (r = -0.205; P = 0.04) appeared significantly correlated to larval tolerance to deltamethrin.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon.

ABSTRACT
The poor management of the urban environment in sub-Saharan Africa is affecting Anopheles gambiae susceptibility to insecticides. A study was undertaken to assess the influence of breeding sites physicochemical parameters on malaria vectors population tolerance to insecticides. A total of 18, 262 larvae collected from 104 breeding sites were exposed to diagnostic concentrations of permethrin and deltamethrin. Larvae originating from cultivated sites were more tolerant than larvae from polluted or nonpolluted sites. No significant difference was observed between polluted and nonpolluted sites. Field larvae were 142 to 325 times and 6.08 to 9.57 times more tolerant to deltamethrin and permethrin, respectively, than larvae of the A. gambiae Kisumu strain used as control. A low but significant correlation was detected between physicochemical parameters and larval insecticide tolerance. Cultivated sites were negatively and significantly correlated to larval tolerance to both deltamethrin (r = -0.421; P < 0.0001) and permethrin (r = -0.392; P < 0.0001). Dissolved oxygen (r = +0.466; P < 0.0001) and ammonia (r = -0.205; P = 0.04) appeared significantly correlated to larval tolerance to deltamethrin. The data suggest a direct correlation between some characteristics from the breeding sites and larval tolerance to pyrethroids.

No MeSH data available.


Related in: MedlinePlus

Diagrams showing mortality rates of third and fourth instars larvae after exposure to sublethal concentrations of permethrin and deltamethrin in Yaoundé ((a) and (b)) and Douala ((c) and (d)).
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fig1: Diagrams showing mortality rates of third and fourth instars larvae after exposure to sublethal concentrations of permethrin and deltamethrin in Yaoundé ((a) and (b)) and Douala ((c) and (d)).

Mentions: Diagnostic concentrations established after exposing the A. gambiae kisumu strain with mortality rates ranging between 10 and 100% were 0.04, 0.06, 0.09, and 0.24 mg/L for permethrin and 0.002, 0.005, 0.03, 0.65 mg/L for deltamethrin, respectively. A total of 18,262 late third instars or fourth instars larvae collected from the field were exposed to these diagnostic concentrations. Larvae collected from cultivated areas were more tolerant (low mortality) to both permethrin and deltamethrin than larvae originating from polluted or nonpolluted sites (P < 0.001). No significant difference was recorded for the mortality rate of larvae originating from polluted and nonpolluted sites in either Yaoundé (Figures 1(a) and 1(b)) or Douala (Figures 1(c) and 1(d)) (P > 0.05). The lethal concentration killing 50% of larvae (LC50) varied from 0.425 to 0.670 mg/L for permethrin and 0.284 to 0.651 mg/L for deltamethrin (Table 2).


Water Quality and Anopheles gambiae Larval Tolerance to Pyrethroids in the Cities of Douala and Yaoundé (Cameroon).

Tene Fossog B, Kopya E, Ndo C, Menze-Djantio B, Costantini C, Njiokou F, Awono-Ambene P, Antonio-Nkondjio C - J Trop Med (2012)

Diagrams showing mortality rates of third and fourth instars larvae after exposure to sublethal concentrations of permethrin and deltamethrin in Yaoundé ((a) and (b)) and Douala ((c) and (d)).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3376768&req=5

fig1: Diagrams showing mortality rates of third and fourth instars larvae after exposure to sublethal concentrations of permethrin and deltamethrin in Yaoundé ((a) and (b)) and Douala ((c) and (d)).
Mentions: Diagnostic concentrations established after exposing the A. gambiae kisumu strain with mortality rates ranging between 10 and 100% were 0.04, 0.06, 0.09, and 0.24 mg/L for permethrin and 0.002, 0.005, 0.03, 0.65 mg/L for deltamethrin, respectively. A total of 18,262 late third instars or fourth instars larvae collected from the field were exposed to these diagnostic concentrations. Larvae collected from cultivated areas were more tolerant (low mortality) to both permethrin and deltamethrin than larvae originating from polluted or nonpolluted sites (P < 0.001). No significant difference was recorded for the mortality rate of larvae originating from polluted and nonpolluted sites in either Yaoundé (Figures 1(a) and 1(b)) or Douala (Figures 1(c) and 1(d)) (P > 0.05). The lethal concentration killing 50% of larvae (LC50) varied from 0.425 to 0.670 mg/L for permethrin and 0.284 to 0.651 mg/L for deltamethrin (Table 2).

Bottom Line: No significant difference was observed between polluted and nonpolluted sites.A low but significant correlation was detected between physicochemical parameters and larval insecticide tolerance.Dissolved oxygen (r = +0.466; P < 0.0001) and ammonia (r = -0.205; P = 0.04) appeared significantly correlated to larval tolerance to deltamethrin.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon.

ABSTRACT
The poor management of the urban environment in sub-Saharan Africa is affecting Anopheles gambiae susceptibility to insecticides. A study was undertaken to assess the influence of breeding sites physicochemical parameters on malaria vectors population tolerance to insecticides. A total of 18, 262 larvae collected from 104 breeding sites were exposed to diagnostic concentrations of permethrin and deltamethrin. Larvae originating from cultivated sites were more tolerant than larvae from polluted or nonpolluted sites. No significant difference was observed between polluted and nonpolluted sites. Field larvae were 142 to 325 times and 6.08 to 9.57 times more tolerant to deltamethrin and permethrin, respectively, than larvae of the A. gambiae Kisumu strain used as control. A low but significant correlation was detected between physicochemical parameters and larval insecticide tolerance. Cultivated sites were negatively and significantly correlated to larval tolerance to both deltamethrin (r = -0.421; P < 0.0001) and permethrin (r = -0.392; P < 0.0001). Dissolved oxygen (r = +0.466; P < 0.0001) and ammonia (r = -0.205; P = 0.04) appeared significantly correlated to larval tolerance to deltamethrin. The data suggest a direct correlation between some characteristics from the breeding sites and larval tolerance to pyrethroids.

No MeSH data available.


Related in: MedlinePlus