SENS_GRAV · Gravity perception: molecular, cellular and adaptive behavior

Although gravity sensation is not easy to sense, it is extrapolated by combining multisensory information. Due to this integrative nature of gravity perception, the knowledge regarding the molecular and neural basis of gravity sensing is highly reduced. The relevance of geotaxis behaviors in insect pest crop survival has been well documented. For instance, harvesting maize imposes a positive geotaxis behavior on the European corn borer (Ostrinia nubilalis), where diapause larvae and pupae are found close to the ground (contrary to what is observed in wild conditions). This adaptive behavior increases its survival and, indeed, its agricultural damage. In addition, larvae show a stereotype orientation when diapausing, suggesting that gravity vector plays a critical role in maggot spatial perception and physiology. In Drosophila, a well-studied insect genetic model, the maggot has a positive geotaxis at early stages, which changes to negative geotaxis at the wandering time (prepupariation period). However, magot gravity perception has never been confirmed or studied. Interestingly, wandering larvae exit the food source searching for an appropriate pupation site, displaying body position and orientation changes. Herein, I propose to take advantage of wandering orientation changes to set up a novel geotaxis behavioral assay and disclose gravity sensory modality in the maggot by i) screening for sensory organs involved in gravity sensing, ii) disclosing the neurocircuitry involved in puparium orientation behavior, and iii) studying the consequences of puparium orientation alteration on adult fitness. I expect this exploratory proposal to establish a solid basis for working further in the physiological impact of insect spatial orientation and the practical use of this knowledge on pest management.