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Wolbachia-based population control strategy targeting Culex quinquefasciatus mosquitoes proves efficient under semi-field conditions.

Atyame CM, Cattel J, Lebon C, Flores O, Dehecq JS, Weill M, Gouagna LC, Tortosa P - PLoS ONE (2015)

Bottom Line: This property can be used to reduce the density of mosquito field populations through inundative releases of incompatible males in order to sterilize females (Incompatible Insect Technique, or IIT, strategy).The results indicated that the LR[wPip(Is)] males successfully compete with field males in mating with field females, displaying even higher competitiveness than field males in April.Our results support the implementation of small-scale field tests in order to assess the feasibility of IIT against Cx. quinquefasciatus in the islands of southwestern Indian Ocean where this mosquito species is a proven competent vector for human pathogens.

View Article: PubMed Central - PubMed

Affiliation: CRVOI, Ste Clotilde, Réunion Island, France; University La Réunion, Réunion Island, France.

ABSTRACT
In mosquitoes, the maternally inherited bacterial Wolbachia induce a form of embryonic lethality called cytoplasmic incompatibility (CI). This property can be used to reduce the density of mosquito field populations through inundative releases of incompatible males in order to sterilize females (Incompatible Insect Technique, or IIT, strategy). We have previously constructed the LR[wPip(Is)] line representing a good candidate for controlling field populations of the Culex quinquefasciatus mosquito in the islands of the south-western Indian Ocean. The main purpose of the present study was to fill the gap between laboratory experiments and field implementation, i.e. assessing mating competitiveness of these incompatible males under semi-field conditions. In a first set of experiments, we analyzed crossing relationships between LR[wPip(Is)] males and La Réunion field females collected as larvae in 19 distinct localities throughout the island. This investigation revealed total embryonic mortality, confirming the strong sterilizing capacity of LR[wPip(Is)] males. Subsequently, mating competitiveness of LR[wPip(Is)] males was assessed under semi-field conditions in the presence of field males and females from La Réunion. Confrontations were carried out in April and December using different ratios of LR[wPip(Is)] to field males. The results indicated that the LR[wPip(Is)] males successfully compete with field males in mating with field females, displaying even higher competitiveness than field males in April. Our results support the implementation of small-scale field tests in order to assess the feasibility of IIT against Cx. quinquefasciatus in the islands of southwestern Indian Ocean where this mosquito species is a proven competent vector for human pathogens.

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Survival curves of field males (N = 220; dotted line) and LR[wPip(Is)] males (N = 177; solid line) in the semi-field setup.
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pone.0119288.g003: Survival curves of field males (N = 220; dotted line) and LR[wPip(Is)] males (N = 177; solid line) in the semi-field setup.

Mentions: Since males’ survival may affect mating competitiveness and thus sterilizing programs, we compared the survival of LR[wPip(Is)] and field males. The overall survival of LR[wPip(Is)] males recaptured from cages at the end of confrontations was not significantly different from that of field males, when considering all replicates or only the 1:1 ratio replicates (Kruskal-Wallis test, all: chi-squared = 0.176, df = 1, P = 0.67, 1:1 ratio: chi-squared = 0.10, df = 1, P = 0.75; Table 2). Moreover, no significant effect of the experimental period on males survival was noted (Kruskal-Wallis test, chi-squared = 3.57, df = 1, P = 0.06). Daily survival of field males (N = 220) and LR[wPip(Is)] males (N = 177) was also investigated by counting dead males placed in separated cages in the semi-field setup. The survival of field males was higher than that of LR[wPip(Is)] during the first 13 days of monitoring, whilst LR[wPip(Is)] males survival was the highest from day 13 to day 28 (Fig. 3). However, when comparing the overall survival of both male categories, no significant difference was observed (χ2 = 2.78, P = 0.09, Fig. 3).


Wolbachia-based population control strategy targeting Culex quinquefasciatus mosquitoes proves efficient under semi-field conditions.

Atyame CM, Cattel J, Lebon C, Flores O, Dehecq JS, Weill M, Gouagna LC, Tortosa P - PLoS ONE (2015)

Survival curves of field males (N = 220; dotted line) and LR[wPip(Is)] males (N = 177; solid line) in the semi-field setup.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4359102&req=5

pone.0119288.g003: Survival curves of field males (N = 220; dotted line) and LR[wPip(Is)] males (N = 177; solid line) in the semi-field setup.
Mentions: Since males’ survival may affect mating competitiveness and thus sterilizing programs, we compared the survival of LR[wPip(Is)] and field males. The overall survival of LR[wPip(Is)] males recaptured from cages at the end of confrontations was not significantly different from that of field males, when considering all replicates or only the 1:1 ratio replicates (Kruskal-Wallis test, all: chi-squared = 0.176, df = 1, P = 0.67, 1:1 ratio: chi-squared = 0.10, df = 1, P = 0.75; Table 2). Moreover, no significant effect of the experimental period on males survival was noted (Kruskal-Wallis test, chi-squared = 3.57, df = 1, P = 0.06). Daily survival of field males (N = 220) and LR[wPip(Is)] males (N = 177) was also investigated by counting dead males placed in separated cages in the semi-field setup. The survival of field males was higher than that of LR[wPip(Is)] during the first 13 days of monitoring, whilst LR[wPip(Is)] males survival was the highest from day 13 to day 28 (Fig. 3). However, when comparing the overall survival of both male categories, no significant difference was observed (χ2 = 2.78, P = 0.09, Fig. 3).

Bottom Line: This property can be used to reduce the density of mosquito field populations through inundative releases of incompatible males in order to sterilize females (Incompatible Insect Technique, or IIT, strategy).The results indicated that the LR[wPip(Is)] males successfully compete with field males in mating with field females, displaying even higher competitiveness than field males in April.Our results support the implementation of small-scale field tests in order to assess the feasibility of IIT against Cx. quinquefasciatus in the islands of southwestern Indian Ocean where this mosquito species is a proven competent vector for human pathogens.

View Article: PubMed Central - PubMed

Affiliation: CRVOI, Ste Clotilde, Réunion Island, France; University La Réunion, Réunion Island, France.

ABSTRACT
In mosquitoes, the maternally inherited bacterial Wolbachia induce a form of embryonic lethality called cytoplasmic incompatibility (CI). This property can be used to reduce the density of mosquito field populations through inundative releases of incompatible males in order to sterilize females (Incompatible Insect Technique, or IIT, strategy). We have previously constructed the LR[wPip(Is)] line representing a good candidate for controlling field populations of the Culex quinquefasciatus mosquito in the islands of the south-western Indian Ocean. The main purpose of the present study was to fill the gap between laboratory experiments and field implementation, i.e. assessing mating competitiveness of these incompatible males under semi-field conditions. In a first set of experiments, we analyzed crossing relationships between LR[wPip(Is)] males and La Réunion field females collected as larvae in 19 distinct localities throughout the island. This investigation revealed total embryonic mortality, confirming the strong sterilizing capacity of LR[wPip(Is)] males. Subsequently, mating competitiveness of LR[wPip(Is)] males was assessed under semi-field conditions in the presence of field males and females from La Réunion. Confrontations were carried out in April and December using different ratios of LR[wPip(Is)] to field males. The results indicated that the LR[wPip(Is)] males successfully compete with field males in mating with field females, displaying even higher competitiveness than field males in April. Our results support the implementation of small-scale field tests in order to assess the feasibility of IIT against Cx. quinquefasciatus in the islands of southwestern Indian Ocean where this mosquito species is a proven competent vector for human pathogens.

Show MeSH