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The effect of restricted air supply on some insects which infest grain
Author(s) -
OXLEY T. A.,
WICKENDEN GLORIA
Publication year - 1963
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1963.tb03698.x
Subject(s) - biology , population , sitophilus , oxygen , toxicology , humidity , relative humidity , zoology , moisture , insect , horticulture , botany , chemistry , demography , physics , organic chemistry , sociology , thermodynamics
SUMMARY If insect pests of grain develop in a strictly airtight container all are killed by exhaustion of oxygen when the concentration of this gas falls to approximately 2%. If the walls of the container permit limited access of oxygen from the atmosphere by diffusion, at a rate dependent on the difference between the internal and external concentrations, the insect population may also be killed, but this will depend on the amount of diffusion and on the level of the original population. A method for investigating this in the laboratory using polythene diaphragms to admit oxygen is described. A population of six adult Sitophilus granarius per pound of wheat in a container admitting 7·5 mg. of oxygen per litre per day at zero internal concentration will not be killed immediately but will be reduced to a very low level and may eventually die out after many months. In the same container a smaller number of insects may survive sufficiently long to increase in numbers to a level at which they also are killed. At a critical population level (about twelve adults per pound) there may occur sharp fluctuations in oxygen concentration, and presumably of insect activity, which may or may not lead to death. A population initially much greater than twelve adults per pound will certainly be killed although this may take a little longer than in an airtight container. If the container is substantially full of wheat having a moisture content near 14% the apparent respiratory quotient of the insects is about 0·69 but if the proportion of the air space occupied by wheat is reduced, the apparent respiratory quotient is increased until it is approximately unity when the volume of wheat is about 5% of the volume of the container. It is concluded that carbon dioxide is adsorbed by wheat in proportion to the concentration of the gas.