Feeding site selection in Rhodnius prolixus nymphs, American trypanosomiasis vector

• Rhodnius prolixus nymphs exhibit a significant preference for the paws of anesthetized mice during host contact experiments. • Local skin temperature strongly influences attachment site selection, with insect density increasing 9% per 1 °C rise. • Feeding activity by multiple nymphs causes localized temperature drops in the paws and tail, reflecting heat redistribution. • Accessibility and thermal cues together modulate the choice of biting sites, probably optimizing blood acquisition efficiency. Thermal cues are fundamental for host-seeking in kissing bugs, primary vectors of American trypanosomiasis. Host surface temperature may reflect underlying vascular richness, potentially guiding feeding site selection. In this study, we investigated whether Rhodnius prolixus nymphs preferentially select specific regions of a mammalian host and whether local skin temperature influences this choice. Nymphs from first to fifth instars were allowed to feed on anesthetized mice, and insect densities were recorded across distinct body regions (head, lateral abdomen, paws and tail). Mouse body temperature was recorded using a thermal imaging camera and analyzed with generalized linear and mixed-effects models. Nymphs of all instars distributed across the host body but consistently preferred the paws, particularly in early instars. Local skin temperature was associated with attachment rates, with each 1 °C increase associated with a 9% rise in insect density. Thermographic analyses revealed that mice exposed to feeding nymphs exhibited greater temperature declines in the paws and tail, suggesting localized effects of blood extraction on heat distribution. Together, these results indicate that R. prolixus nymphs integrate physical accessibility and thermal cues when selecting feeding sites, a behavior that may optimize blood acquisition under natural conditions