Chemosensory sensilla

At the same time insects are able to discriminate between host and non-host plant species as they select plants on which feeding ultimately results in growth and reproduction, and on the other hand avoid poisoning or malnutrition on non-host plants. By means of chemosensory sensilla, insects are able to perform the difficult task, being well equipped analytical chemists, of identifying the chemical composition of plants that insects meet in their environment (6). 

Figure 1. The head of a Pieris brassicae larva. The chemosensory sensilla are...

Dickens J. C., Callahan F. E., Wergin W. P, Murphy C. A. and Vogt R. G. (1998) Odorantbinding proteins of true bugs. Generic specificity, sexual dimorphism, and association with subsets of chemosensory sensilla. Ann. NY Acad. Sci. 855, 306-10. 

Xu A., Park S.-K., Domello D., Kim E., Wang Q. and Pikielny C. (2002) Novel genes expressed in subsets of chemosensory sensilla on the front legs of male Drosophila. Cell Tissue Res. 307, 381-392. 

Insect chemosensory organs have been differentially developed for taste and olfactory sensing. The contact and the distant chemosensory sensilla are responsible for nonvolatile and volatile chemical reception, respectively. The CHCs with long carbon chains are non-volatile, and therefore thought to be received by taste sensilla (Ebbs and Amrein, 2007). However, because of their insolubility in water, it was very difficult to obtain response recordings to them from taste sensilla. Success was recently obtained, however, in Drosophila melanogaster, where a male-specific CHC as a sex-pheromone inhibiting male-male courtship was found to stimulate the bitter taste receptor neuron within the... 

Tip-recording method for electrophysiological study of chemosensory sensilla... 

Mead KS, Koehl MAR, O Donnell MJ (1999) Stomatopod sniffing the scaling of chemosensory sensillae and flicking behavior with body size. J Exp Mar Biol Ecol 241 235-261... 

The study of chemosensory sensilla morphology may provide answers to questions about how the chemosensory organs function and why they function as they do. The main questions in this research field are What do crustacean chemosensory sensilla look like (exterior and interior) Why are they similar or dissimilar How can the morphology be correlated to function What are the functional modalities of these sensory organs ... 

Fig. 6.1 Artist s drawing of a crayfish showing some locations for important chemosensory sensilla. Above the crayfish the antennule is where the unimodal (olfactory) chemosensory aesthetascs are situated. To the left of the crayfish on the tips of the walking legs, bimodal chemo- and mechanosensory sensilla may be present e.g., as hedgehog hairs (above left) and smooth, squamose setae (below left). Bimodal sensilla show a considerable structural variety and can also be found e.g., on the mouthparts of the animal (not shown). Drawing by artist Jorge A. Varela Ramos...

The fine structure of crustacean chemosensory sensilla has been comprehensively described during the last 50 years (Laverack 1968,1988 Altner and Prillinger 1980 ... 

As mentioned above, some crustacean groups also exhibit sexual dimorphism in the types of chemosensory sensilla present on the antennulae. In these species the males (but not females) have an array of slender sensory hairs, called male-specific sensilla, on the peduncle of the antennule (Fig. 6.6a, b). These male-specific sensilla appear to be characteristic for some taxa within the order Peracarida, e.g., mysids, certain amphipods, and possibly cumaceans (Johansson and Hallberg 1992). 

Crustaceans are found in many different habitats with a range of physical challenges (e.g., salinity, temperature, air/water) for the chemosensory organs, which also show a considerable morphological variation among crustacean taxa. The general ultrastructure and fine structure of crustacean chemosensory sensilla have been... 

Foraging (e.g., food finding, evaluation and acquisition), agonistic and reproductive behaviors are contexts where chemosensory cues and chemosensory sensilla are essential for most crustaceans. Of those three topics, the role of chemoreception and chemical signals in reproductive behaviors is least understood and needs more research effort in the future. In particular, the role of pheromone receptors in mate-finding and evaluation, courtship, copulation, and brood care is... 

Even in those crustacean species where visible morphological sex differences in the chemosensory sensilla are small or imperceptible, variations of aesthetasc structure, size and number, sensory cell morphology, and spatial arrangement can still occur. Any such sexual dimorphism could help enlighten the sex-specific role of these chemosensory structures in, for example, reproductive behaviors. 

The aesthetascs are olfactory sensilla and usually all chemoreception mediated by the lateral antennular flagella (or the entire antennules) was attributed to them and hence considered as olfaction. This interpretation is flawed because other chemosensory sensilla are associated with the aesthetascs and likely the activity of dCRNs in these bimodal sensilla was analyzed in most axon recordings from the lateral flagella. 

Mead K, Koehl MAR (2000) Particle image velocimetry measurements of fluid flow through a model array of mantis shrimp chemosensory sensilla. J Exp Biol 203 3795-3808... 

Mead KS, Weatherby TM (2002) Morphology of mantis shrimp chemosensory sensilla facilitates fluid sampling. Invert Biol 121 148-157... 

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