From gene to behavior: uncovering TRPA1 function in chemical avoidance in an insect

Blood-feeding insects rely on chemical cues to avoid harmful compounds, yet the mechanisms underlying deterrent detection remain poorly understood in Chagas disease vectors. We investigated how Rhodnius prolixus detects two electrophilic deterrents: allyl isothiocyanate (AITC) and N-ethylmaleimide (NEM), both known TRPA1 activators. In dual-choice behavioral assays, R. prolixus displayed significant contact avoidance to both compounds. Covering the antennae abolished NEM avoidance, while AITC avoidance persisted even with covered antennae or tarsi, suggesting that both or alternative sensory structures are involved. At the molecular level, RNAi-mediated knockdown of TRPA1 selectively abolished AITC avoidance, confirming its role in this sensory pathway. We conducted an in silico sequence and structural analysis and identified conserved reactive residues in R. prolixus (C714 and C758) corresponding to functional sites in fruitfly and mammals. AlphaFold 3D modeling of TRPA1 homotetramer showed a pore architecture similar to D. melanogaster Cryo-EM structures and revealed the spatial arrangement of these cysteines. Our findings show that electrophilic deterrents engage distinct sensory organs in R. prolixus, with TRPA1 required specifically for AITC avoidance. Persistence of NEM avoidance post-knockdown indicates additional detection mechanisms for harmful electrophiles. We provide new insights into the molecular basis of chemical nociception in blood-feeding insects.