An Experimental Study of Feeding, Basking, Marching and Pottering in Locust Nymphs

Autor: Peggy E. Ellis
Rok vydání: 1963
Předmět:
Zdroj: Behaviour. 20:282-309
ISSN: 1568-539X
0005-7959
DOI: 10.1163/156853963x00040
Popis: [1. The amount of time spent in marching, basking, pottering and feeding was measured in small groups of gregarious fourth-instar hoppers of two locust species Locusta migratoria migratorioides (R. & F.) and Schistocerca gregaria (Forsk.) under various conditions in the laboratory. 2. The factors tested were: a change from darkness to light, a room temperature falling from 31° to 27° C in two hours, a room temperature rising from 20° C to 29° C in two hours, and a nearly constant room temperature of 20-21° C or 30-31° C for four hours, the presence or absence of radiant heat and the presence or absence of slow air currents. 3. Marching was stimulated by a rising air temperature, but reduced by a falling one over the range 20-34° C. If cage temperatures were above 34° C, marching was stimulated a little by a falling temperature. There was significantly more marching at a constant temperature of 30-35.5° C than at 20-26° C, but at the lower temperatures the presence of a source of radiant heat, acting at least in part through its effect on cage temperature, significantly increased marching. At constant cage temperatures between 20 and 26° C, air currents slightly reduced marching, but between 30 and 35.5° C they greatly increased it. Following a change from darkness to light there was a burst of marching when the air temperature was 30° C and the air was still. 4. Basking depended on a source of radiant heat and uneven heating of the cage walls and floor. Overall temperature conditions appeared to play a part. At a constant room temperature of 30-31° C, maximum basking was shown with both low and high amounts of radiant heat. At room temperatures of 20-21° C basking was only maximal in cages with high amounts of radiant heat. At constant temperatures air currents always decreased basking, especially in Schistocerca. When the air temperature was rising basking was reduced a little, but when it was falling basking was sometimes reduced a little and sometimes increased. 5. Pottering was affected by the environmental conditions in a similar way to marching, although the size of the differences was smaller. 6. The amount of time spent on feeding fluctuated irregularly. Changing temperatures had no effect on feeding, while a change from darkness to light inhibited it a little. There tended to be more feeding in Schistocerca at cage temperatures of 22-34° C and less at lower and higher cage temperatures. In both species feeding was generally rhythmical, with peaks every 11/2-3 hours. 7. The experiments showed that there were various differences between the two locust species. On the whole, most of them could be explained by assuming a wider optimal range for the various conditions in Locusta than Schistocerca, especially in relation to marching and basking. Locusta hoppers tended to show greater changes in marching behaviour, and Schistocerca greater changes in basking behaviour, in relation to the different conditions. 8. The various experimental results are discussed in relation to field observations on the behaviour of locust hoppers., 1. The amount of time spent in marching, basking, pottering and feeding was measured in small groups of gregarious fourth-instar hoppers of two locust species Locusta migratoria migratorioides (R. & F.) and Schistocerca gregaria (Forsk.) under various conditions in the laboratory. 2. The factors tested were: a change from darkness to light, a room temperature falling from 31° to 27° C in two hours, a room temperature rising from 20° C to 29° C in two hours, and a nearly constant room temperature of 20-21° C or 30-31° C for four hours, the presence or absence of radiant heat and the presence or absence of slow air currents. 3. Marching was stimulated by a rising air temperature, but reduced by a falling one over the range 20-34° C. If cage temperatures were above 34° C, marching was stimulated a little by a falling temperature. There was significantly more marching at a constant temperature of 30-35.5° C than at 20-26° C, but at the lower temperatures the presence of a source of radiant heat, acting at least in part through its effect on cage temperature, significantly increased marching. At constant cage temperatures between 20 and 26° C, air currents slightly reduced marching, but between 30 and 35.5° C they greatly increased it. Following a change from darkness to light there was a burst of marching when the air temperature was 30° C and the air was still. 4. Basking depended on a source of radiant heat and uneven heating of the cage walls and floor. Overall temperature conditions appeared to play a part. At a constant room temperature of 30-31° C, maximum basking was shown with both low and high amounts of radiant heat. At room temperatures of 20-21° C basking was only maximal in cages with high amounts of radiant heat. At constant temperatures air currents always decreased basking, especially in Schistocerca. When the air temperature was rising basking was reduced a little, but when it was falling basking was sometimes reduced a little and sometimes increased. 5. Pottering was affected by the environmental conditions in a similar way to marching, although the size of the differences was smaller. 6. The amount of time spent on feeding fluctuated irregularly. Changing temperatures had no effect on feeding, while a change from darkness to light inhibited it a little. There tended to be more feeding in Schistocerca at cage temperatures of 22-34° C and less at lower and higher cage temperatures. In both species feeding was generally rhythmical, with peaks every 11/2-3 hours. 7. The experiments showed that there were various differences between the two locust species. On the whole, most of them could be explained by assuming a wider optimal range for the various conditions in Locusta than Schistocerca, especially in relation to marching and basking. Locusta hoppers tended to show greater changes in marching behaviour, and Schistocerca greater changes in basking behaviour, in relation to the different conditions. 8. The various experimental results are discussed in relation to field observations on the behaviour of locust hoppers.]
Databáze: OpenAIRE