The survival and molting incidence in
Triatoma infestans
, a vector of Chagas disease, were investigated following sequential shocks
at 0°C in fifth instar nymphs under moderate fasting and full nutritional
conditions. The shocks were separated by intervals of 8 h and 24 h at 30°C.
The results indicated that in terms of insect survival,
T. infestans
is tolerant to a single cold shock at 0°C even for 12 h, or to sequential
cold shocks, regardless of the nutritional state of the specimens. In terms
of molting rate, fasting enhanced the tolerance to sequential cold shocks,
but did not exceed the tolerance acquired by fully-nourished specimens,
except when cold shocks were separated by an 8 h interval at 30°C.
The protective action elicited by fasting was assumed to be additive to
that induced by a single mild cold shock or sequential cold shocks. The
cold-tolerance response of
T. infestans
may have favoured its survival in areas of South America with low temperatures,
even considering that this species is predominantly associated with human
habitats.
