The myoinhibiting peptides (MIPs), also designated as allatostatin-Bs or prothoracicostatic peptides in some insects, are neuropeptides that are characterized by two tryptophan (W) residues at the C-terminal, denoted as the W(X₆)Wamide motif. They are believed to be the ancestral ligands for the Drosophila sex peptide (SP) receptor. Physiological functions of MIPs include the inhibition of contraction of insect visceral muscles, in addition to allatostatic and prothoracicostatic activities. The MIP precursor in Rhodnius prolixus encodes MIPs that have an unusual W(X₇)Wamide motif. In the present study, MIP-like immunoreactivity was detected within neurons in the central nervous system and within the innervation to the salivary glands, hindgut, and female and male reproductive systems of adult R. prolixus. The effects of peptides with the unusual W(X₇)Wamide motif (Rhopr-MIP-4) and with the typical W(X₆)Wamide motif (Rhopr-MIP-7) were tested for physiological activity on R. prolixus hindgut contractions. Both peptides reduce the frequency and amplitude of hindgut contractions in a dose-dependent manner. In addition, both peptides activate the Drosophila SP receptor. The MIP/SP receptors are therefore activated by peptides with the unusual W(X₇)Wamide motif.

The blood-sucking hemipteran Rhodnius prolixus is a vector of Chagas disease, one of the most neglected tropical diseases affecting several million people, mostly in Latin America. The blood meal is an event with a high epidemiological impact since adult mated females feed several times, with each meal resulting in a bout of egg laying, and thereby the production of hundreds of offspring. By means of RNA-Sequencing (RNA-Seq) we have examined how a blood meal influences mRNA expression in the central nervous system (CNS), fat body and ovaries in order to promote egg production, focusing on tissue-specific responses under controlled nutritional conditions. We illustrate the cross talk between reproduction and a) lipids, proteins and trehalose metabolism, b) neuropeptide and neurohormonal signaling, and c) the immune system. Overall, our molecular evaluation confirms and supports previous studies and provides an invaluable molecular resource for future investigations on different tissues involved in successful reproductive events. These analyses serve as a starting point for new investigations, increasing the chances of developing novel strategies for vector population control by translational research, with less impact on the environment and more specificity for a particular organism. The blood-sucking hemipteran Rhodnius prolixus is one of the main vectors of Chagas disease. The blood meal is an event with a high epidemiological impact since adult mated females take several blood meals, with each meal resulting in the laying of a batch of eggs, thereby resulting in hundreds of offspring. This work describes an in-depth central nervous system (CNS), ovary and fat body transcriptome analysis, focusing on transcripts related to blood intake which may be relevant in promoting egg production. To date, the principle focus in Chagas disease prevention is on the elimination of triatomine vectors and their progeny. This work will serve as a starting point for initiating novel investigations on targets identified with a potential for use in vector control; for example, using specific genes to generated symbiont-mediated RNAi, a powerful technology which provides a novel means in biocontrol against tropical disease vectors.