The ultrastructure of an olfactory sensillum on the maxillary palps of Locusta migratoria (L.)

1977 ◽  
Vol 184 (3) ◽  
Author(s):  
W.M. Blaney
1972 ◽  
Vol 57 (3) ◽  
pp. 755-763
Author(s):  
E. A. BERNAYS ◽  
R. F. CHAPMAN

1. The electrical resistance across the tips of the maxillary palps is not affected by stimulation of the palps, but increases to the normal level found after feeding as a result of distension of the foregut with agar or injection of corpus cardiacum homogenates into the haemolymph. 2. No increase in resistance occurs if the posterior pharyngeal nerves or the frontal connectives are cut. 3. It is inferred that distension of the foregut stimulates stretch receptors which, acting via the posterior pharyngeal nerves, the frontal connectives and the brain, cause the release of hormone from the storage lobes of the corpora cardiaca. This hormone acts on the terminal sensilla of the palps, causing them to close and so increasing the resistance across the palps. 4. Release of the diuretic hormone is controlled via the same pathway.


1975 ◽  
Vol 63 (3) ◽  
pp. 701-712
Author(s):  
W. M. Blaney ◽  
A. M. Duckett

Palpation increases the amount of sensory input reaching the central nervous system compared with that obtained from sustained contact but that increase is not essential to allow discrimination. During a meal on favoured food, phagostimulatory input from the palps is not needed to drive feeding. When less favoured food is taken, phagostimulatory input from the palps may enhance feeding. Even with favoured food, the palps are important in registering inhibitory substances.


1975 ◽  
Vol 62 (3) ◽  
pp. 555-569
Author(s):  
W. M. Blaney

1. Behavioural studies show that larvae of Locusta migratoria (L.) can discriminate between certain simple chemicals and between chemicals obtained from plant sources. 2. Electrophysiological tests show that within each sensillum the same neurones respond to different chemicals. 3. The frequency of occurrence of sensilla with enhanced specificity to certain chemicals is investigated. 4. Statistical tests confirm that, despite the variability of response, across-fibre analysis could allow discrimination between chemicals provided an adequate number of senilla are used. 5. The conclusions are discussed in relation to current theories of chemoreceptor functioning.


1974 ◽  
Vol 60 (2) ◽  
pp. 275-293
Author(s):  
W. M. BLANEY

1. Three morphologically and functionally different types of sensilla on the maxillary palp tips of Locusta migratoria are distinguished and an electrophysiological study is made of the most commonly occurring type. 2. Responses to stimulation with 0.1 M sodium chloride show impulses of one, two or three amplitude categories in different sensilla. 3. Variability of response to a constant stimulus is appreciable, both between and within sensilla. 4. Tests with a range of compounds indicate that individual neurones are capable of responses to compounds of different chemical classes. 5. Specificity of sensilla is more marked than specificity of neurones. 6. Methods of interpretation of results are evaluated and the results are discussed in the context of discrimination of food plant materials.


1972 ◽  
Vol 57 (3) ◽  
pp. 745-753 ◽  
Author(s):  
E. A. BERNAYS ◽  
W. M. BLANEY ◽  
R. F. CHAPMAN

1. The electrical resistance across the tips of the maxillary palps of Locusta migratoria is high immediately after a feed, but falls to a steady level in about 2 h after feeding. 2. Only a small proportion of the individual sensilla on the domes of the palps respond to chemical stimulation immediately after feeding, but this proportion increases with the period of food deprivation. 3. Gentle manipulation of the tips of non-responsive sensilla causes them to respond. 4. It is suggested that the terminal pores of the sensilla can open and close and that the resistance across the tips of the palps varies inversely with the number of open sensilla. 5. The possible significance of the changes is discussed.


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