Entomopathogenic nematodes (Heterorhabditidae and Steinernematidae), to control Triatoma infestans populations (Hemiptera: Reduviidae), Chagas disease vector

Pyrethroid insecticides are the only strategy to control Triatoma infestans populations (Hemiptera: Reduviidae), the main vector of Chagas disease in Argentina. However, toxicity effects and resistance have resulted from repeated applications of these insecticides over long periods. The aim of this study was to evaluate the efficacy of three isolates of entomopathogenic nematodes (EPN): Heterorhabditis bacteriophora (RN and SUP strains) and Steinernema feltiae (NEMAPOM), against pyrethroid-resistant and non-resistant T. infestans populations. Survival of pyrethroid-resistant and non-resistant T. infestans nymphs was significantly reduced in those parasitized by EPN strains compared to the controls, reaching values close to 10%, three and six days after exposure to Heterorhabditis and Steinernema, respectively. The lowest survival of T. infestans nymphs resulted from application of H. bacteriophora strains. No significant differences were observed between pyrethroid-resistant and non-resistant T. infestans populations for any of the parameters evaluated. The three strains were able to multiply and emerge as infective juveniles (IJs) from T. infestans cadavers, completing their lifecycle in both pyrethroid-resistant and non-resistant populations, but highest IJ production was observed in H. bacteriophora strains. Future studies should consider the incorporation of drought-tolerant EPN strains, as well as evaluating an adequate release strategy before field imple- mentation of EPNs as biological control agents of T. infestans.

Automated summary

The study showed that entomopathogenic nematodes can effectively reduce the survival rate of pyrethroid-resistant and non-resistant Triatoma infestans nymphs, and all three strains were able to multiply and emerge as infective juveniles from the cadavers of the insects. Highest infective juvenile production was observed in H. bacteriophora strains. Future research should focus on incorporating drought-tolerant EPN strains and evaluating release strategies for effective biological control of T. infestans.