Are phlebotomine sand flies (Diptera: Psychodidae) really attracted to UV-light sources?

Phlebotomine sand flies are the sole confirmed vector of leishmaniosis, a group of endemic and re-emerging diseases in southern European countries such as Spain. Light traps are the major surveillance method currently being employed. Nevertheless, color light attraction by sand flies remains mostly unknown. Following prior research, the effect of UV-LED light sources, and its synergic effect with different color lights has been evaluated employing a modified Flebocollect (FC) light trap model. Results suggest that female Phlebotomus perniciosus sand flies are more attracted to a FC trap lured with the combination of blue and UV LED light sources than commercial CDC (Center for Disease Control and prevention) traps (Bonferroni post-hoc test; p < 0.08; blue/UV mean = 0.50; CDC mean = 0.13), while the combination of red and UV modified-traps excel in capturing Sergentomyia minuta sand flies (Bonferroni post-hoc test; p < 0.04; blue/UV mean = 1.19; CDC mean = 0.66). However, based on our prior studies, incorporating UV light sources into sand fly traps does not seem to enhance their attractiveness, as it has not resulted in higher capture rates. These findings contribute to understanding how sand flies' vision and light color detection is. Further research is recommended to standardize trap construction procedures and explore variations in different endemic regions according to different sand fly species.

Imidazolium salt's toxic effects in larvae and cells of Aedes aegypti and Aedes albopictus (Diptera: Culicidae).

Aedes aegypti and Aedes albopictus are the main vectors of arboviruses such as Dengue, Chikungunya and Zika, causing a major impact on global economic and public health. The main way to prevent these diseases is vector control, which is carried out through physical and biological methods, in addition to environmental management. Although chemical insecticides are the most effective strategy, they present some problems such as vector resistance and ecotoxicity. Recent research highlights the potential of the imidazolium salt "1-methyl-3-octadecylimidazolium chloride" (C18MImCl) as an innovative and environmentally friendly solution against Ae. aegypti. Despite its promising larvicidal activity, the mode of action of C18MImCl in mosquito cells and tissues remains unknown. This study aimed to investigate its impacts on Ae. aegypti larvae and three cell lines of Ae. aegypti and Ae. albopictus, comparing the cellular effects with those on human cells. Cell viability assays and histopathological analyses of treated larvae were conducted. Results revealed the imidazolium salt's high selectivity (> 254) for mosquito cells over human cells. After salt ingestion, the mechanism of larval death involves toxic effects on midgut cells. This research marks the first description of an imidazolium salt's action on mosquito cells and midgut tissues, showcasing its potential for the development of a selective and sustainable strategy for vector control.

Same parasite, different outcomes: unraveling the epidemiology of Leishmania infantum infection in Brazil and Spain.

Human leishmaniosis caused by Leishmania infantum is an important health problem worldwide. One of the main aspects arousing interest is the epidemiological scenario surrounding Le. infantum infection in the New World (NW) and Old World (OW). This parasite was introduced to the Americas during European colonization leading to different epidemiology outcomes, even more enigmatic in the face of global changes. Thus, this review aims to highlight the differences and similarities between Le. infantum epidemiology between Brazil (NW) and Spain (OW), as both countries are leading the total number of leishmaniosis cases in their respective continents. Grounded on a systemic view, this article also draws attention to possible common innovative strategies to rethink ways of controlling infections caused by Le. infantum.

Galactosamine reduces sandfly gut protease activity through TOR downregulation and increases Lutzomyia susceptibility to Leishmania.

In sandflies, males and females feed on carbohydrates but females must get a blood meal for egg maturation. Using artificial blood meals, this study aimed to understand how galactosamine interferes with sandfly digestive physiology. We also used galactosamine to manipulate the digestive physiology of Lutzomyia longipalpis to investigate its influence on sandfly digestion and Leishmania development within their insect vectors. Galactosamine was capable to reduce Lu. longipalpis trypsinolytic activity in a dose-dependent manner. This effect was specific to galactosamine as other similar sugars were not able to affect sandfly trypsin production. An excess of amino acids supplemented with the blood meal and 15 mM galactosamine was able to abrogate the reduction of the trypsinolytic activity caused by galactosamine, suggesting this phenomenon may be related to an impairment of amino acid detection by sandfly enterocytes. The TOR inhibitor rapamycin reduces trypsin activity in the L. longipalpis midgut. Galactosamine reduces the phosphorylation of the TOR pathway repressor 4EBP, downregulating TOR activity in the gut of L. longipalpis. Galactosamine reduces sandfly oviposition, causes an impact on sandfly longevity and specifically reduces sandfly gut proteases whereas increasing α-glycosidase activity. The administration of 15 and 30 mM galactosamine increased the number of promastigote forms of Le. mexicana and Le. infantum in galactosamine-treated L. longipalpis. Our results showed that galactosamine influences amino acid sensing, reduces sandfly gut protease activity through TOR downregulation, and benefits Leishmania growth within the Lu. longipalpis gut.