Coinfection byTrypanosoma cruziand a fungal pathogen increases survival of Chagasic bugs: advice against a fungal control strategy

摘要

Triatomine bugs carry the parasitic protozoaTrypanosoma cruzi, the causal agent of Chagas disease. It is known that both the parasite and entomopathogenic fungi can decrease bug survival, but the combined effect of both pathogens is not known, which is relevant for biological control purposes. Herein, the survival of the triatomineMeccus pallidipennis(Stal, 1872) was compared when it was coinfected with the fungusMetarhizium anisopliae(Metschnikoff) andT. cruzi, and when both pathogens acted separately. The immune response of the insect was also studied, using phenoloxidase activity in the bug gut and hemolymph, to understand our survival results. Contrary to expectations, triatomine survival was higher in multiple than in single challenges, even though the immune response was lower in cases of multiple infection. We postulate thatT. cruziexerts a protective effect and/or that the insect reduced the resources allocated to defend itself against both pathogens. Based on the present results, the use ofM. anisopliaeas a control agent should be re-considered.