Larval locomotion

Drosophila larvae show stereotyped locomotion behavior. They navigate with specific strategies and also show aggregation and dispersal behaviors. However, the mechanisms coordinating larval locomotion in respect to other animals, especially in close proximity and during/after physical contacts are currently only little understood. In this context we assay how and when relevant information is perceived by the larvae. We analyze the influence on behavior before or during larva-larva collision, and ask whether larvae avoid or pursue collisions. Employing a new method developed in the lab that is based on frustrated total internal reflection-based imaging (FIM) we already found that larvae visually detect other moving larvae in a narrow perceptive field and respond with characteristic escape reactions. To further decipher larval locomotion not only before but also during the collision we developed a two color FIM approach (FIM2c), which allowed to faithfully extract the posture and motion of colliding animals. We show that during collision, larval locomotion freezes and sensory information is sampled during a KISS phase (german: Kollisions Induziertes Stopp Syndrom or english: collision induced stop syndrome). Interestingly, larvae react differently to living, dead or artificial larvae, discriminate other Drosophila species and have an increased bending probability for a short period after the collision terminates. Thus, Drosophila larvae evolved means to specify behaviors in response to other larvae.