The chemosensory system of the Drosophila larva: an overview of current understanding

Abstract

Animals must sense their surroundings and be able to distinguish between relevant and irrelevant cues. An enticing area of research aims to uncover the mechanisms by which animals respond to chemical signals that constitute critical sensory input. In this review, we describe the principles of a model chemosensory system: the Drosophila larva. While distinct in many ways, larval behaviour is reminiscent of the dogmatic goals of life: to reach a stage of reproductive potential. It takes into account a number of distinct and identifiable parameters to ultimately provoke or modulate appropriate behavioural output. In this light, we describe current knowledge of chemosensory anatomy, genetic components, and the processing logic of chemical cues. We outline recent advancements and summarize the hypothesized neural circuits of sensory systems. Furthermore, we note yet-unanswered questions to create a basis for further investigation of molecular and systemic mechanisms of chemosensation in Drosophila and beyond.

IR76b-expressing neurons in Drosophila melanogaster are necessary for associative reward learning of an amino acid mixture

“…Taken together, our study provides an example of how many aspects of the gustatory system are still not well understood and much more complex than anticipated (see also [ 32 ]), and uncovers unexpected complexity in how the larval gustatory periphery is wired up with the brain interneurons that confer valence. This, in a model organism with few neurons and excellent genetic tools, is an excellent study case to investigate the details of such division of labour in future research.…”

Evolution of temperature preference behaviour among drosophilids

“…For example, in response to olfactory cues, larvae modulate speed in response to aversive and attractive odour gradients 62 , and similar changes in speed have been observed on thermogradients 63 . In addition, because a larva’s non-noxious thermosensors are located at the tip of their head 42 (along with sensors that detect other environmental cues 64,65 ), the initiation of turns is established by first probing their environment using head sweeps. As negative thermal stimuli evoke larger turns 31 , larger head sweeps are expected to reflect increasingly aversive temperatures compared to head sweeps in preferred temperatures 31 (or other favoured stimuli; wind 66 , light 67 , olfactory 68 ) (Fig.…”

Identification of 2,4-Di-tert-butylphenol as a Novel Agonist for Insect Odorant Receptors

“…Odor molecules activate ORs located within the sensillum pores on the insect’s antennae and maxillary palps, thus generating nerve impulses [ 4 ]. These nerve impulses are transmitted to the olfactory sensory neurons (OSNs) through the aqueous medium within the nerve fibers and are then interpreted by the nervous system [ 5 , 6 , 7 ]. The olfactory system plays a crucial role in determining insect behaviors, such as host plant preference, oviposition site selection, mate choice, and danger avoidance, all of which directly impact their survival [ 8 ].…”