RESUMEN
The mosquito Aedes aegypti is an important vector of diseases including dengue, Zika, chikungunya, and yellow fever. Olfaction is a critical modality for mosquitoes enabling them to locate hosts, sources of nectar, and sites for oviposition. GABA is an essential neurotransmitter in olfactory processing in the insect brain, including the primary olfactory center, the antennal lobe. Previous work with Ae. aegypti has suggested that antennal lobe inhibition via GABA may be involved in the processing of odors. However, little is known about GABA receptor expression in the mosquito brain, or how they may be involved in odor attraction. In this context, generating mutants that target the mosquito's olfactory responses, and particularly the GABAergic system, is essential to achieve a better understanding of these diverse processes and olfactory coding in these disease vectors. Here we demonstrate the potential of a transgenic line using the QF2 transcription factor, GABA-B1QF2-ECFP, as a new neurogenetic tool to investigate the neural basis of olfaction in Ae. aegypti. Our results show that the gene insertion has a moderate impact on mosquito fitness. Moreover, the line presented here was crossed with a QUAS reporter line expressing the green fluorescent protein and used to determine the location of the metabotropic GABA-B1 receptor expression. We find high receptor expression in the antennal lobes, especially the cell bodies surrounding the antennal lobes. In the mushroom bodies, receptor expression was high in the Kenyon cells, but had low expression in the mushroom body lobes. Behavioral experiments testing the fruit odor attractants showed that the mutants lost their behavioral attraction. Together, these results show that the GABA-B1QF2-ECFP line provides a new tool to characterize GABAergic systems in the mosquito nervous system.
RESUMEN
Arthropod control mechanisms are a vital part of public health measures around the world as many insect species serve as vectors for devastating human diseases. Aedes aegypti (Linnaeus, 1762) is a widely distributed, medically important mosquito species that transmits viruses such as yellow fever, Dengue, and Zika. Many traditional control mechanisms have become less effective due to insecticide resistance or exhibit unwanted off-target effects, and, consequently, there is a need for novel solutions. The use of attractive toxic sugar baits (ATSBs) has increased in recent years, though the toxic elements are often harmful to humans and other vertebrates. Therefore, we are investigating propylene glycol, a substance that is generally regarded as safe (GRAS) for human consumption. Using a series of feeding assays, we found that propylene glycol is highly toxic to Ae. aegypti adults and a single day of exposure significantly reduces the survivorship of test populations compared with controls. The effects are more pronounced in males, drastically reducing their survivorship after one day of consumption. Additionally, the consumption of propylene glycol reduced the survivorship of two prominent disease vectors: Aedes albopictus (Skuse, 1894) and Culex pipiens (Linnaeus, 1758). These findings indicate that propylene glycol could be used as a safe and effective alternative to pesticides in an ATSB system.
