Abstract
BackgroundLittle is known about how human disease vectors will modify their life history patterns and survival capacity as a result of climate change. One case is that of Chagas disease, which has triatomine bugs and Trypanosoma cruzi as vectors and parasite, respectively. This work aimed to determine: (i) the activity of the prophenoloxidase system (prophenoloxidase and phenoloxidase activity, two indicators of immune ability) in three intestine regions (anterior midgut, posterior midgutand rectum) of the triatomine bug Meccus pallidipennis under three temperature conditions (20 °C, 30 °C and 34 °C) against two T. cruzi strains [ITRI/MX/14/CHIL (Chilpancingo) and ITRI/MX/12/MOR (Morelos)], and (ii) whether vector survival varies under these three temperatures after infection by these T. cruzi strains.ResultsOur results indicate that prophenoloxidase activity was lower at higher temperatures, that the level of prophenoloxidase activity elicited by each strain was different (higher in Chilpancingo than in Morelos strains), and that prophenoloxidase activity was more intense in the anterior midgut than in the posterior midgut or rectum. Survival rates were lower in insects maintained at higher temperatures and infected by Chilpancingo strains.ConclusionsThese results indicate that climate change could lead to lower prophenoloxidase activity and survival rates in triatomines when infected with different T. cruzi strains, which could reduce the vector capacity of M. pallidipennis.
Highlights
Little is known about how human disease vectors will modify their life history patterns and survival capacity as a result of climate change
Results proPO activity with respect to infection status, temperature and intestine region Significant differences were observed in the linear model with respect to infection status (Chilpancingo, Morelos and control), incubation temperature (20 °C, 30 °C and 34 °C) and intestine region (AMG, posterior midgut (PMG) and rectum; Table 1)
The intestine region was a good predictor of proPO, where the anterior midgut (AMG) yielded higher activity levels than the PMG and rectum, with no significant differences between the latter groups (Fig. 3)
Summary
Little is known about how human disease vectors will modify their life history patterns and survival capacity as a result of climate change. Recent projections indicate an increase in the distribution of vector insects and the prevalence of the diseases they transmit [6, 7], considering that insects are ectothermic (i.e. basic physiological functions such as locomotion, growth and reproduction are strongly influenced by environmental temperature) [8] and that higher temperatures will promote shorter life-cycles and more rapid reproduction [9, 10]. The relationship between T. cruzi and its vectors could modulate these temperature thresholds [20, 21], possibly due to resource cost-related factors and manipulation by the parasite [22]
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