Adaptive developmental delay in Chagas disease vectors: an evolutionary ecology approach

Area of Science:

• Vector biology
• Evolutionary ecology
• Epidemiology

Background:

• Triatomine insects, vectors of Chagas disease, exhibit variable developmental times.
• Understanding this variability is crucial for population dynamics, disease epidemiology, and predicting responses to climate change.
• Evolutionary ecology concepts have not been widely applied to triatomine biology.

Purpose of the Study:

• To investigate the causes and adaptive significance of developmental delays in triatomine insects.
• To explore the potential role of diapause as a risk-spreading strategy in response to environmental stochasticity.

Main Methods:

• Survey of 30 triatomine researchers regarding developmental delays.
• Statistical analysis of developmental time in eleven triatomine species.
• Mathematical modeling to explore the evolution of developmental delay (diapause).

Main Results:

• 85.6% of surveyed researchers reported prolonged developmental times in fifth-instar nymphs.
• Twenty triatomine species showed significant developmental delays.
• A bimodal pattern in fifth-instar development was observed in nine of eleven species, but no correlation with inter-annual climate variability was found.
• Mathematical models suggest developmental delays could be an adaptive diapause strategy under specific survival and environmental condition probabilities.

Conclusions:

• Developmental delays in triatomines may represent an adaptive diapause, not just phenotypic plasticity.
• This strategy could be a form of bet-hedging, adapting to environmental stochasticity by postponing reproduction.
• Further field and laboratory studies are needed to test this hypothesis, with implications for climate change and disease epidemiology.