Figure 1.
Collecting sites of Cx. pipiens pallens field populations.
(A) The mosquito populations were collected from eastern China; (B) Three collecting sites Tangkou, Nanjing and Wuxi are shown in detail. The mosquito populations collected are designated TK, NJ and WX, respectively.
Table 1.
Genes used for Wolbachia typing and their PCR amplification primers.
Figure 2.
Reproductive compatibilities between three Cx. pipiens pallens field populations.
Three Cx. pipiens pallens field populations NJ, WX and TK were used in reciprocal crosses to test their reproductive compatibilities. For each cross, an equal number of virgin females and males were kept in a cage for 48 hours before blood feeding. After oviposition, egg rafts were collected and allowed to hatch. The average hatching rates of these crosses were compared. (A) Mating combinations of NJ and WX populations, (B) Mating combinations of TK and WX populations, (C) Mating combinations of NJ and TK populations. Error bars represent standard errors; ns, non-significant P-value; *** P<0.0001 by t-test.
Figure 3.
Effect of subsequent encounter with cognate males on the fecundity of the females retrieved from incompatible crosses.
Females were retrieved from the two incompatible crosses as shown in Figure 2B. TK or WX females were equally divided into two subgroups, with one mixed with cognate males and the other kept alone (no male). After a second blood feeding and oviposition, egg rafts were collected and allowed to hatch. The average hatching rates of these subgroups were compared. Error bars represent standard errors; ns, non-significant P-value.
Figure 4.
Incompatible males competitively suppress reproduction in a dose-dependent manner.
Females were mixed with cognate males and an increasing number of incompatible males. They were given 48 hours before blood feeding. The average hatching rates of these crosses were compared. Subsequently, females were retrieved and divided equally into two subgroups, with one mixed with cognate males and the other kept alone. The average hatching rates of these subgroups were compared. (A) TK♀ mixed with TK♂ and WX♂; (B) WX♀ mixed with WX♂ and TK♂; (C) TK♀ retrieved from A were mixed with TK♂ or kept alone; (D) WX♀ retrieved from B were mixed with WX♂ or kept alone. Error bars represent standard errors; ns, non-significant P-value; *** P<0.0001; * P<0.05 by t-test.
Figure 5.
Correlation between group average hatching rate and the percentage of incompatible males.
The average hatching rate of a group was plotted against the percentage of incompatible males which was calculated by dividing the number of incompatible males by the total number of males (incompatible and cognate). (A) TK females with TK and WX males; (B) WX females with WX and TK males.
Figure 6.
Reproductive compatibilities of F1 offspring from incompatible crosses.
F1 offspring from TK and WX crosses were mixed with TK, WX or the F1. The hatching rates were compared. (A) F1 from TK♀×WX♂ cross; (B) F1 from WX♀×TK♂ cross. Error bars represent standard errors; ns, non-significant P-value; *** P<0.0001 by t-test.
Figure 7.
Elimination of Wolbachia rendered TK and WX populations fully compatible.
WX females were crossed with an equal number of tetracycline-treated TK males (TKtet♂), untreated TK males (TK♂) or WX males (WX♂). TK females were crossed with an equal number of tetracycline-treated WX males (WXtet♂), untreated WX males (WX♂) or TK males (TK♂). Hatching rates were calculated for these crosses. Error bars represent standard errors; ns, non-significant P-value; *** P<0.0001 by t-test.