Intestinal flow and digestive parameters of Lutzomyia longipalpis larvae

• Published in: Journal of insect physiology 2025-03, Vol.161, p.104748, Article 104748
• Main Authors: Malta, Luccas Gabriel Ferreira, Ribeiro, Bianca Stacanelli, Viegas-Melo, Davi, Pinho-Junior, Marques Serafim, Sant’Anna, Maurício Roberto Viana, Pereira, Marcos Horário, Gontijo, Nelder Figueiredo
• Format: Article
• Language: English
• Subjects: absorption; aminopeptidases; Countercurrent flux; Diet; digestion; Enzymes; etiological agents; insect physiology; insects; instars; Intestinal flow; intestinal mucosa; larvae; Leishmania infantum; Lutzomyia longipalpis; nutrient availability; secretion; soil; species; trypsin; visceral leishmaniasis
• ISSN: 0022-1910; 1879-1611; 1879-1611
• DOI: 10.1016/j.jinsphys.2025.104748

[Display omitted] •L. longipalpis larvae display variable intestinal flow according to the diet.•The intestinal flow time was measured as 191 min.•Amino acids and proteins stimulate trypsin production.•Aminopeptidasic activity is little influenced by amino acids in the diet.•Countercurrent flow has been demonstrated in L. longipalpis larvae. Lutzomyia longipalpis Lutz & Neiva, 1912 (Diptera, Psychodidae), is the primary vector of Leishmania infantum Nicole, 1908, the etiological agent of American visceral leishmaniasis. During their development, sandfly larvae pass through four instars, consuming soil particles enriched with microorganisms and decomposing organic material. In numerous insect species, the intestinal epithelium not only secretes digestive enzymes and absorbs digested nutrients but also carries out additional functions, such as regulating luminal pH and facilitating the absorption or secretion of ions and water. The transport of ions and water plays a crucial role in the establishment of a countercurrent flow responsible for recycling soluble digestive enzymes. This study aimed to explore specific aspects of digestion in L. longipalpis larvae that remain poorly understood. We measured the intestinal flow within the endoperitrophic space, which varied depending on the type of diet offered to the larvae, with an average total time of 191 min. Additionally, we demonstrated the countercurrent flow in L. longipalpis larvae. Finally, we showed that the production of digestive enzymes can be modulated by nutrient availability, particularly by the amino acids in the larval diet. The higher the amino acids concentration, the higher the trypsin activity. On the other hand, the aminopeptidase activity was poorly influenced by the amino acids concentration.