Fig 1.
The mean blood ingestion ratio of Rhodnius prolixus blood-fed at different developmental stages.
The blood ingestion ratio is the blood-fed body weight of each individual triatomine divided by its own unfed body weight immediately prior to blood-feeding. The entire dataset from all triatomine individuals (i.e., of every experimental group) was analyzed simultaneously controlling for developmental stage, as well as temperature and infection treatments. The blood ingestion ratio showed a significant decrease with triatomine developmental stage (Wald statistic = 24.97 p = 5.8e-07, n = 185). Error bars represent the upper and lower limit of the Gaussian confidence interval.
Fig 2.
Variation in the mean molting time after blood-feeding of Rhodnius prolixus at different triatomine developmental stages and ambient temperatures.
The entire dataset from all triatomine individuals (i.e., of every experimental group) was analyzed simultaneously controlling for developmental stage, as well as temperature and infection treatments. The duration of the inter-molt period for each developmental stage transition differed significantly between the four temperatures investigated (p < 2e-16 for all six comparisons between temperature treatments) and progressively increased at every developmental stage (Wald statistic = 2142.91 and p < 2e-16). (Overall, n = 197.) Error bars represent the standard error of the mean.
Fig 3.
Survival rate of Rhodnius prolixus maintained at four different temperatures during the 185 days of the experiment.
The entire dataset from all triatomine individuals (i.e., of every experimental group) was analyzed simultaneously controlling for temperature and infection treatments. The insects kept at 30°C had lower survival than those kept at 24°C and 26°C (p = 0.0318 an p = 0.016, respectively, with Cox proportional hazards regression model). Overall, n = 208, with n = 52 per temperature treatment group.
Fig 4.
Mean retention performance of Rhodnius prolixus at different triatomine developmental stages and ambient temperatures.
Retention performance measures the proportion of the weight of the blood meal ingested in the previous nymphal instar that is maintained as triatomine body weight in the next instar, and is calculated for each individual as the weight gained between triatomine developmental stages divided by the weight of the blood ingested by the previous nymphal instar. The entire dataset from all triatomine individuals (i.e., of every experimental group) was analyzed simultaneously controlling for developmental stage, as well as temperature and infection treatments. The triatomines kept at 30°C had a significantly lower retention performance compared to the other three temperature treatment groups (comparison with: the 24°C treatment, Wald statistic = 6.22 and p = 0.013; the 26°C treatment, Wald statistic = 8.72 and p = 0.0032; and the 28°C treatment, Wald statistic = 22.8 and p = 1.79e-06; n = 173 for all comparisons). Additionally, retention performance decreased with developmental stages (Wald statistic = 981.38 and p < 2e-16). Error bars represent the standard error of the mean.
Fig 5.
Correlation between retention performance at the fourth instar and the quantity of blood ingested in the third instar in uninfected Rhodnius prolixus.
When the data from all four uninfected temperature treatment groups investigated were pooled and analyzed together, there was a significant linear correlation (R2 = 0.1789, p = 3.631e-05, n = 85). Grey shaded area indicates the standard error of the regression line.
Fig 6.
Correlation between retention performance and parasite concentration in excreted urine for Trypanosoma cruzi-infected Rhodnius prolixus kept at 28°C.
A. Third instar nymphs (R2 = 0.3745, p = 0.0155, n = 13). B. Fourth instar nymphs (R2 = 0.5308, p = 0.001246, n = 15). Grey shaded area indicates the standard error of the regression line.
Fig 7.
The mean parasite concentration in the excreted urine of Trypanosoma cruzi-infected Rhodnius prolixus at different triatomine developmental stages.
The data from infected insects of all four temperature treatment was analyzed simultaneously controlling for developmental stage, unfed weight, and temperature treatment. The parasite concentration differed significantly between different triatomine developmental stages (Wald statistic = 64.90 and p = 7.8e-16, n = 75). Error bars represent the standard error of the mean.
Fig 8.
Generalized Estimating Equation (GEE) analysis showing the effect of ambient temperature on the mean parasite concentration in the excreted urine of Trypanosoma cruzi-infected Rhodnius prolixus at different nymphal instars.
The parasite concentration of the 24°C treatment group was significantly lower compared to the other three temperature treatment groups (comparison with: the 30°C treatment, Wald statistic = 6.08 and p = 0.014; the 28°C treatment, Wald statistic = 9.53 and p = 0.002; and the 26°C treatment, Wald statistic = 4.64 and p = 0.031; n = 75 for all comparisons). Confidence bands represent standard error.
Fig 9.
Correlation between the concentration of Trypanosoma cruzi parasites in the excreted urine and the unfed body weight of fifth instar nymphs of Rhodnius prolixus kept at 26°C (R2 = 0.313, p = 0.0176, n = 15).
Grey shaded area indicates the standard error of the regression line.
Fig 10.
Correlation between parasite concentration in the excreted urine of Trypanosoma cruzi-infected Rhodnius prolixus and the quantity of uninfected blood ingested in the previous nymphal instar at different triatomine developmental stages and ambient temperatures.
A. Fourth instar nymphs from the 26°C temperature treatment (R2 = 0.435, p = 0.0117, n = 12), B. Fifth instar nymphs from the 26°C treatment (R2 = 0.5212, F(1,13) = 16.24, p = 0.00143, n = 15). C. Fourth instar nymphs from the 28°C treatment (R2 = 0.453, F(1,13) = 12.59, p = 0.00357, n = 14). Shaded grey area represents the standard error of the regression line.
Fig 11.
Correlation between the parasite concentration in the excreted urine of Trypanosoma cruzi-infected Rhodnius prolixus at the third and fourth nymphal instars (R2 = 0.3526, p = 0.000161, n = 33).
Grey shaded area indicates the standard error of the regression line.