The ACBP gene family in Rhodnius prolixus: Expression, characterization and function of RpACBP-1

The Rpfor gene modulates the locomotory activity and host-seeking behaviour of Rhodnius prolixus

The molecular bases of animal behaviour are intricate due to the pleiotropic nature of behaviour-modulating genes, which are often expressed across multiple tissues. The foraging gene (for) encodes a cGMP-dependent protein kinase (PKG), pivotal in regulating downstream target proteins through phosphorylation. In insects, for has been implicated in various behavioural contexts and physiological processes regarding searching for food. Rhodnius prolixus, a hematophagous bug that transmits Trypanosoma cruzi, the causative agent of Chagas disease, exhibits specific activity patterns associated with its hematophagous behaviour. Our previous work demonstrated a correlation between locomotor activity profiles and the expression of Rpfor, suggesting its involvement in modulating triatomine locomotion. In this study, we investigated the impact of Rpfor knockdown on locomotory activity, host-seeking behaviour, feeding performance and lipid metabolism in R. prolixus nymphs. Using RNA interference, we achieved a significant reduction of Rpfor expression in both the brain and fat body of R. prolixus nymphs. Knocked-down nymphs exhibited diminished non-oriented locomotory activity compared with controls, without altering the characteristic bimodal pattern of activity. Additionally, they displayed an increased tendency to approach a host, suggesting a role for Rpfor in modulating host-seeking behaviour. Feeding performance and lipid metabolism remained unaffected by Rpfor knockdown. Our findings underscore the multifaceted role of Rpfor in modulating locomotor activity and host-seeking behaviour in R. prolixus nymphs, shedding light on the molecular mechanisms underlying their hematophagous behaviour and potential implications for disease transmission. Further research is necessary to elucidate the intricate interplay between Rpfor expression, behaviour and physiological processes in triatomine bugs.

Lipophorin receptor knockdown reduces hatchability of kissing bug Rhodnius prolixus eggs

Lipophorin is the primary lipoprotein present in the hemolymph of insects, responsible for the lipids' transport between organs. It interacts with specific sites on cell membranes in an essential process for transferring lipids. The lipophorin receptor is the protein responsible for the interaction between lipophorin and cell membranes. In the kissing bug Rhodnius prolixus, much information on the interaction of lipophorin with organs is available. However, molecular data on the lipophorin receptor and its functions is still needed. Here, we explored lipophorin receptor gene expression and functions using a functional genomics approach. The R. prolixus genome encodes seven genes from the low-density lipoprotein receptor family, including a single ortholog of the lipophorin receptor. All organs analyzed (anterior and posterior midguts, fat body, ovaries, and flight muscle) expressed this gene. In the fat body, blood-feeding strongly reduced lipophorin receptor gene expression. Lipophorin receptor knockdown by RNA interference delayed egg laying and reduced the triacylglycerol in laid eggs without altering lipid stores in the fat body or lipid levels in the hemolymph. In the ovaries, lipophorin receptor knockdown reduces the expression of acetyl-CoA carboxylase and a fatty acid synthase while altered the gene expression profile in the fat body, causing an increase in the expression of carnitine palmitoyltransferase 1 and a reduction in Brummer lipase and vitellogenin 2. RNA interference treatment reduced the hatching of the eggs, causing the collapse and darkening of the laid eggs, in addition to the hatching of deformed first-stage nymphs. Furthermore, the structure of the chorion showed distortions in patterns and cracks and reduced hydrocarbon levels. These results show that the lipophorin receptor alone is not essential for lipid physiology in R. prolixus. However, this protein plays a fundamental role in the viability of eggs and, consequently, in insect reproduction.

Water fluxes and nutrient absorption along the midgut of three hemipterans, Mahanarva fimbriolata, Dysdercus peruvianus, and Rhodnius prolixus

Hemiptera Order comprises insect species adapted to different diets regarding water and nutrient content and availability, thus suggesting different combinations of proteins to ensure their absorption. To find out whether hemipterans use the same or distinct set of proteins and whether these differences are related to the phylogeny or the diet, RNAseq analyses were conducted in gut sections of three hemipterans, M. fimbriolata, D. peruvianus, and R. prolixus, with remarkable distinct diet. Since only a few of the selected proteins were functionally characterized, the coded putative proteins were manually curated by bioinformatics to infer their physiological function. The results suggest a relationship between gene expression patterns and water and nutrient dietary content and availability. In contrast, putative gene expansions and deletions are related to phylogeny, corresponding to evolutionary adaptations of ancestral forms to feed on xylem, cotton seeds, and blood, resulting in more resemblances between D. peruvianus and R. prolixus than M. fimbriolata. M. fimbriolata absorbs water through aquaporins Drip and Prip in the filtration chamber by passive diffusion, with a higher contribution of water-selective Drip. D. peruvianus water absorption involves Drip and Prip, but Prip contribution appears to be higher, and they probably cooperate with water-ion cotransporters in the posterior midgut. R. prolixus absorbs water in the anterior midgut involving a sodium transporter and a putative water-urea Prip. Sugars, amino acids, and lipids might be absorbed along the midgut in the three species, with a higher contribution of the posterior midgut for amino acid and lipid absorption in M. fimbriolata and D. peruvianus and the middle midgut in R. prolixus.

Honey Bee Larval Hemolymph as a Source of Key Nutrients and Proteins Offers a Promising Medium for Varroa destructor Artificial Rearing

Varroa destructor, a major ectoparasite of the Western honey bee Apis mellifera, is a widespread pest that damages colonies in the Northern Hemisphere. Throughout their lifecycle, V. destructor females feed on almost every developmental stage of their host, from the last larval instar to the adult. The parasite is thought to feed on hemolymph and fat body, although its exact diet and nutritional requirements are poorly known. Using artificial Parafilm™ dummies, we explored the nutrition of V. destructor females and assessed their survival when fed on hemolymph from bee larvae, pupae, or adults. We compared the results with mites fed on synthetic solutions or filtered larval hemolymph. The results showed that the parasites could survive for several days or weeks on different diets. Bee larval hemolymph yielded the highest survival rates, and filtered larval plasma was sufficient to maintain the mites for 14 days or more. This cell-free solution therefore theoretically contains all the necessary nutrients for mite survival. Because some bee proteins are known to be hijacked without being digested by the parasite, we decided to run a proteomic analysis of larval honey bee plasma to highlight the most common proteins in our samples. A list of 54 proteins was compiled, including several energy metabolism proteins such as Vitellogenin, Hexamerin, or Transferrins. These molecules represent key nutrient candidates that could be crucial for V. destructor survival.

Alterations in energy metabolism of Rhodnius prolixus induced by Trypanosoma rangeli infection

Trypanosoma rangeli is a protozoan parasite that infects triatomines and mammals in the Americas, producing mixed infections with Trypanosoma cruzi, the etiological agent of Chagas disease. The former parasite is not pathogenic to humans, but has different levels of pathogenicity, as well as causing physiological and behavioral alterations, to its invertebrate hosts. In this study, we measured locomotory activity, and the glyceride accumulation profile in the hemolymph and fat body, as well as the expression of key genes related to triglyceride metabolism, of Rhodnius prolixus nymphs infected with T. rangeli. We found that the locomotory activity of the insects was correlated with the amount of triglycerides in the fat body. Infected nymphs had increased activity when starved, and also had an accumulation of glycerides in the fat body and hemolymph. These alterations were also associated with a higher expression of the diacylglycerol acyltransferase, lipophorin and lipophorin receptor genes in the fat body. We infer that T. rangeli is able to alter the energetic processes of its invertebrate host, in order to increase the availability of lipids to the parasite, which, in turn modifies the activity levels of the insect. These alterations are discussed with regard to their potential to increase the transmission rate of the parasite.

Trypanosoma cruzi Affects Rhodnius prolixus Lipid Metabolism During Acute Infection

The interaction between Rhodnius prolixus and Trypanosoma cruzi has huge medical importance because it responds to the transmission of Chagas disease, a neglected tropical disease that affects about eight million people worldwide. It is known that trypanosomatid pathogens depend on active lipid endocytosis from the insect host to meet growth and differentiation requirements. However, until now, knowledge on how the parasite affects the lipid physiology of individual insect organs was largely unknown. Herein, the biochemical and molecular dynamics of the triatomine R. prolixus lipid metabolism in response to T. cruzi acute infection were investigated. A qRT-PCR approach was used to determine the expression profile of 12 protein-coding genes involved in R. prolixus lipid physiology. In addition, microscopic and biochemical assays revealed the lipid droplet profile and the levels of the different identified lipid classes. Finally, spectrometry analyses were used to determine fatty acid and sterol composition and their modulation towards the infection. T. cruzi infection downregulated the transcript levels of protein-coding genes for lipid biosynthetic and degrading pathways in individual triatomine organs. On the other hand, upregulation of lipid receptor transcripts indicates an attempt to capture more lipids from hemolymphatic lipoproteins. Consequently, several lipid classes (such as monoacylglycerol, diacylglycerol, triacylglycerol, cholesteryl ester, phosphatidylcholine, and phosphatidylethanolamine) were involved in the response to the parasite challenge, although modulating only the insect fat body. T. cruzi never leaves the insect gut and yet it modulates non-infected tissues, suggesting that the association between the parasite and the vector organs is reached by cell signaling molecules. This hypothesis raises several intriguing issues to inspire future studies in the parasite-vector interaction field.

Genes involved in the Type I pheromone biosynthesis pathway and chemoreception from the sex pheromone gland transcriptome of Dioryctria abietella

Dioryctria abietella is a coniferous seed orchard pest that can damage a series of host plants and cause huge losses to the forest economy. Sex pheromones play an important role in lepidopteran sex communication for reproduction and can be used as biological control agents to monitor and trap pests. However, the genes involved in the biosynthesis, transportation, and degradation of D. abietella sex pheromones have not been studied extensively. Transcriptome analysis of female D. abietella sex pheromone glands (PGs) revealed that 210 candidate genes might be involved in sex pheromone biosynthesis (139 genes) and chemoreception systems (71 genes). The gene expression patterns exhibited four desaturase genes (DabiDES4-7) and one fatty acid reductase gene (DabiFAR6), which were more highly expressed in sex pheromone glands than in other tissues, suggesting that these enzymes play an important role in D. abietella sex pheromone synthesis. In addition, most DabiOBPs showed high expression in antennae, but only DabiOBP4 exhibited specific expression in sex pheromone glands, suggesting that they may play many physiological roles in D. abietella. We put forth a reasonable hypothesis about type I pheromone biosynthesis pathways based on these genes identified in the D. abietella sex pheromone gland transcriptome. Our findings lay a foundation for population monitoring, mating disruption, mass trapping, and the development of ecologically acceptable management strategies.

Metabolomics provide new insights into mechanisms of Wolbachia-induced paternal defects in Drosophila melanogaster

Wolbachia is a group of intracellular symbiotic bacteria that widely infect arthropods and nematodes. Wolbachia infection can regulate host reproduction with the most common phenotype in insects being cytoplasmic incompatibility (CI), which results in embryonic lethality when uninfected eggs fertilized with sperms from infected males. This suggests that CI-induced defects are mainly in paternal side. However, whether Wolbachia-induced metabolic changes play a role in the mechanism of paternal-linked defects in embryonic development is not known. In the current study, we first use untargeted metabolomics method with LC-MS to explore how Wolbachia infection influences the metabolite profiling of the insect hosts. The untargeted metabolomics revealed 414 potential differential metabolites between Wolbachia-infected and uninfected 1-day-old (1d) male flies. Most of the differential metabolites were significantly up-regulated due to Wolbachia infection. Thirty-four metabolic pathways such as carbohydrate, lipid and amino acid, and vitamin and cofactor metabolism were affected by Wolbachia infection. Then, we applied targeted metabolomics analysis with GC-MS and showed that Wolbachia infection resulted in an increased energy expenditure of the host by regulating glycometabolism and fatty acid catabolism, which was compensated by increased food uptake. Furthermore, overexpressing two acyl-CoA catabolism related genes, Dbi (coding for diazepam-binding inhibitor) or Mcad (coding for medium-chain acyl-CoA dehydrogenase), ubiquitously or specially in testes caused significantly decreased paternal-effect egg hatch rate. Oxidative stress and abnormal mitochondria induced by Wolbachia infection disrupted the formation of sperm nebenkern. These findings provide new insights into mechanisms of Wolbachia-induced paternal defects from metabolic phenotypes.

Gene annotation of nuclear receptor superfamily genes in the kissing bug Rhodnius prolixus and the effects of 20-hydroxyecdysone on lipid metabolism

The hormone 20-hydroxyecdysone is fundamental for regulating moulting and metamorphosis in immature insects, and it plays a role in physiological regulation in adult insects. This hormone acts by binding and activating a receptor, the ecdysone receptor, which is part of the nuclear receptor gene superfamily. Here, we analyse the genome of the kissing bug Rhodnius prolixus to annotate the nuclear receptor superfamily genes. The R. prolixus genome displays a possible duplication of the HNF4 gene. All the analysed insect organs express most nuclear receptor genes as shown by RT-PCR. The quantitative PCR analysis showed that the RpEcR and RpUSP genes are highly expressed in the testis, while the RpHNF4-1 and RpHNF4-2 genes are more active in the fat body and ovaries and in the anterior midgut, respectively. Feeding does not induce detectable changes in the expression of these genes in the fat body. However, the expression of the RpHNF4-2 gene is always higher than that of RpHNF4-1. Treating adult females with 20-hydroxyecdysone increased the amount of triacylglycerol stored in the fat bodies by increasing their lipogenic capacity. These results indicate that 20-hydroxyecdysone acts on the lipid metabolism of adult insects, although the underlying mechanism is not clear.

Debugging: Strategies and Considerations for Efficient RNAi-Mediated Control of the Whitefly Bemisia tabaci

The whitefly Bemisia tabaci is a globally important pest that is difficult to control through insecticides, transgenic crops, and natural enemies. Post-transcriptional gene silencing through RNA interference (RNAi) has shown potential as a pest management strategy against B. tabaci. While genomic data and other resources are available to create highly effective customizable pest management strategies with RNAi, current applications do not capitalize on species-specific biology. This lack of specificity has the potential to have substantial ecological impacts. Here, we discuss both short- and long-term considerations for sustainable RNAi pest management strategies for B. tabaci, focusing on the need for species specificity incorporating both life history and population genetic considerations. We provide a conceptual framework for selecting sublethal target genes based on their involvement in physiological pathways, which has the greatest potential to ameliorate unintended negative consequences. We suggest that these considerations allow an integrated pest management approach, with fewer negative ecological impacts and reduced likelihood of the evolution of resistant populations.

What happens after a blood meal? A transcriptome analysis of the main tissues involved in egg production in Rhodnius prolixus, an insect vector of Chagas disease

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.

Functional characterization of acyl-CoA binding protein in Neospora caninum

Background

Lipid metabolism is pivotal for the growth of apicomplexan parasites. Lipid synthesis requires bulk carbon skeleton acyl-CoAs, the transport of which depends on the acyl-CoA binding protein (ACBP). In Neospora caninum, the causative agent of neosporosis, the FASII pathway is required for growth and pathogenicity. However, little is known about the fatty acid transport mechanism in N. caninum.

Methods

We have identified a cytosolic acyl-CoA binding protein, with highly conserved amino acid residues and a typical acyl-CoA binding domain in N. caninum. The recombinant NcACBP protein was expressed to verify the binding activities of NcACBP in vitro, and the heterologous expression of NcACBP in Δacbp yeast in vivo. Lipid extraction from ΔNcACBP or the wild-type of N. caninum was analyzed by GC-MS or TLC. Furthermore, transcriptome analysis was performed to compare the gene expression in different strains.

Results

The NcACBP recombinant protein was able to specifically bind acyl-CoA esters in vitro. A yeast complementation assay showed that heterologous expression of NcACBP rescued the phenotypic defects in Δacbp yeast, indicating of the binding activity of NcACBP in vivo. The disruption of NcACBP did not perturb the parasite’s growth but enhanced its pathogenicity in mice. The lipidomic analysis showed that disruption of NcACBP caused no obvious changes in the overall abundance and turnover of fatty acids while knockout resulted in the accumulation of triacylglycerol. Transcriptional analysis of ACBP-deficient parasites revealed differentially expressed genes involved in a wide range of biological processes such as lipid metabolism, posttranslational modification, and membrane biogenesis.

Conclusions

Our study demonstrated that genetic ablation of NcACBP did not impair the survival and growth phenotype of N. caninum but enhanced its pathogenicity in mice. This deletion did not affect the overall fatty acid composition but modified the abundance of TAG. The loss of NcACBP resulted in global changes in the expression of multiple genes. This study provides a foundation for elucidating the molecular mechanism of lipid metabolism in N. caninum.

Expression of acyl-CoA-binding protein 5 from Rhodnius prolixus and its inhibition by RNA interference

The acyl-CoA-binding proteins (ACBP) act by regulating the availability of acyl-CoA in the cytoplasm and must have essential functions in lipid metabolism. The genome of the kissing-bug Rhodnius prolixus encodes five proteins of this family, but little is known about them. In this study we investigated the expression and function of RpACBP-5. Feeding induced RpACBP-5 gene expression in the posterior midgut, and an increase of about four times was observed two days after the blood meal. However, the amount of protein, which was only detected in this organ, did not change during digestion. The RpACBP-5 gene was also highly expressed in pre-vitellogenic and vitellogenic oocytes. Recombinant RpACBP-5 was shown to bind to acyl-CoA of different lengths, and it exhibited nanomolar affinity to lauroyl-CoA in an isothermal titration assay, indicating that RpACBP-5 is a functional ACBP. RpACBP-5 knockdown by RNA interference did not affect digestion, egg laying and hatching, survival, or accumulation of triacylglycerol in the fat body and oocytes. Similarly, double knockdown of RpACBP-1 and RpACBP-5 did not alter egg laying and hatching, survival, accumulation of triacylglycerol in the fat body and oocytes, or the neutral lipid composition of the posterior midgut or hemolymph. These results show that RpACBP-5 is a functional ACBP but indicate that the lack of a detectable phenotype in the knockdown insects may be a consequence of functional overlap of the proteins of the ACBP family found in the insect.

The overexpression of rice ACYL-CoA-BINDING PROTEIN2 increases grain size and bran oil content in transgenic rice

As Oryza sativa (rice) seeds represent food for over three billion people worldwide, the identification of genes that enhance grain size and composition is much desired. Past reports have indicated that Arabidopsis thaliana acyl-CoA-binding proteins (ACBPs) are important in seed development but did not affect seed size. Herein, rice OsACBP2 was demonstrated not only to play a role in seed development and germination, but also to influence grain size. OsACBP2 mRNA accumulated in embryos and endosperm of germinating seeds in qRT-PCR analysis, while β-glucuronidase (GUS) assays on OsACBP2pro::GUS rice transformants showed GUS expression in embryos, as well as the scutellum and aleurone layer of germinating seeds. Deletion analysis of the OsACBP2 5'-flanking region revealed five copies of the seed cis-element, Skn-I-like motif (-1486/-1482, -956/-952, -939/-935, -826/-822, and -766/-762), and the removal of any adversely affected expression in seeds, thereby providing a molecular basis for OsACBP2 expression in seeds. When OsACBP2 function was investigated using osacbp2 mutants and transgenic rice overexpressing OsACBP2 (OsACBP2-OE), osacbp2 was retarded in germination, while OsACBP2-OEs performed better than the wild-type and vector-transformed controls, in germination, seedling growth, grain size and grain weight. Transmission electron microscopy of OsACBP2-OE mature seeds revealed an accumulation of oil bodies in the scutellum cells, while confocal laser scanning microscopy indicated oil accumulation in OsACBP2-OE aleurone tissues. Correspondingly, OsACBP2-OE seeds showed gain in triacylglycerols and long-chain fatty acids over the vector-transformed control. As dietary rice bran contains beneficial bioactive components, OsACBP2 appears to be a promising candidate for enriching seed nutritional value.

ACBD6 protein controls acyl chain availability and specificity of the N-myristoylation modification of proteins

Members of the human acyl-CoA binding domain-containing (ACBD) family regulate processes as diverse as viral replication, stem-cell self-renewal, organelle organization, and protein acylation. These functions are defined by nonconserved motifs present downstream of the ACBD. The human ankyrin-repeat-containing ACBD6 protein supports the reaction catalyzed by the human and Plasmodium N-myristoyltransferase (NMT) enzymes. Likewise, the newly identified Plasmodium ACBD6 homologue regulates the activity of the NMT enzymes. The relatively low abundance of myristoyl-CoA in the cell limits myristoylation. Binding of myristoyl-CoA to NMT is competed by more abundant acyl-CoA species such as palmitoyl-CoA. ACBD6 also protects the Plasmodium NMT enzyme from lauryl-CoA and forces the utilization of the myristoyl-CoA substrate. The phosphorylation of two serine residues of the acyl-CoA binding domain of human ACBD6 improves ligand binding capacity, prevents competition by unbound acyl-CoAs, and further enhances the activity of NMT. Thus, ACBD6 proteins promote N-myristoylation in mammalian cells and in one of their intracellular parasites under unfavorable substrate-limiting conditions.

Comprehensive Characterization of Toxoplasma Acyl Coenzyme A-Binding Protein TgACBP2 and Its Critical Role in Parasite Cardiolipin Metabolism

Toxoplasma gondii is one of the most successful human parasites, infecting nearly one-third of the total world population. T. gondii tachyzoites residing within parasitophorous vacuoles (PVs) can acquire fatty acids both via salvage from host cells and via de novo synthesis pathways for membrane biogenesis. However, although fatty acid fluxes are known to exist in this parasite, how fatty acids flow through Toxoplasma lipid metabolic organelles, especially mitochondria, remains unknown. In this study, we demonstrated that Toxoplasma expresses an active ankyrin repeat containing protein TgACBP2 to coordinate cardiolipin metabolism. Specifically, HMA acquisition resulting from heterologous functional expression of MAF1 rescued growth and lipid metabolism defects in ACBP2-deficient type II parasites, manifesting the complementary role of host mitochondria in parasite cardiolipin metabolism. This work highlights the importance of TgACBP2 in parasite cardiolipin metabolism and provides evidence for metabolic association of host mitochondria with T. gondii.

Acyl coenzyme A (CoA)-binding protein (ACBP) can bind acyl-CoAs with high specificity and affinity, thus playing multiple roles in cellular functions. Mitochondria of the apicomplexan parasite Toxoplasma gondii have emerged as key organelles for lipid metabolism and signaling transduction. However, the rationale for how this parasite utilizes acyl-CoA-binding protein to regulate mitochondrial lipid metabolism remains unclear. Here, we show that an ankyrin repeat-containing protein, TgACBP2, is localized to mitochondria and displays active acyl-CoA-binding activities. Dephosphorylation of TgACBP2 is associated with relocation from the plasma membrane to the mitochondria under conditions of regulation of environmental [K⁺]. Under high [K⁺] conditions, loss of ACBP2 induced mitochondrial dysfunction and apoptosis-like cell death. Disruption of ACBP2 caused growth and virulence defects in the type II strain but not in type I parasites. Interestingly, mitochondrial association factor-1 (MAF1)-mediated host mitochondrial association (HMA) restored the growth ability of ACBP2-deficient type II parasites. Lipidomics analysis indicated that ACBP2 plays key roles in the cardiolipin metabolism of type II parasites and that MAF1 expression complemented the lipid metabolism defects of ACBP2-deficient type II parasites. In addition, disruption of ACBP2 caused attenuated virulence of Prugniuad (Pru) parasites for mice. Taking the results collectively, these data indicate that ACBP2 is critical for the growth and virulence of type II parasites and for the growth of type I parasites under high [K⁺] conditions.

Lipid metabolism in insect disease vectors

More than a third of the world population is at constant risk of contracting some insect-transmitted disease, such as Dengue fever, Zika virus disease, malaria, Chagas' disease, African trypanosomiasis, and others. Independent of the life cycle of the pathogen causing the disease, the insect vector hematophagous habit is a common and crucial trait for the transmission of all these diseases. This lifestyle is unique, as hematophagous insects feed on blood, a diet that is rich in protein but relatively poor in lipids and carbohydrates, in huge amounts and low frequency. Another unique feature of these insects is that blood meal triggers essential metabolic processes, as molting and oogenesis and, in this way, regulates the expression of various genes that are involved in these events. In this paper, we review current knowledge of the physiology and biochemistry of lipid metabolism in insect disease vectors, comparing with classical models whenever possible. We address lipid digestion and absorption, hemolymphatic transport, and lipid storage by the fat body and ovary. In this context, both de novo fatty acid and triacylglycerol synthesis are discussed, including the related fatty acid activation process and the intracellular lipid binding proteins. As lipids are stored in order to be mobilized later on, e.g. for flight activity or survivorship, lipolysis and β-oxidation are also considered. All these events need to be finely regulated, and the role of hormones in this control is summarized. Finally, we also review information about infection, when vector insect physiology is affected, and there is a crosstalk between its immune system and lipid metabolism. There is not abundant information about lipid metabolism in vector insects, and significant current gaps in the field are indicated, as well as questions to be answered in the future.