QUANTITATIVE AND QUALITATIVE EFFECTS OF TEMPERATURE AND TYPE OF GRAIN ON POPULATIONS OF SITOPHILUS (COLEOPTERA: CURCULIONIDAE) AND ON THEIR MYCETOMAL MICROORGANISMS

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Abstract
Known numbers of parents of four described different types of Sitophilus weevils, normally reared on wheat at 27 °C, were used, in several experiments, to set up cultures on three kinds of grain at three different temperatures. The resulting progeny were counted and weighed. In an attempt to assess the quality of the populations a "productivity index" was devised as milligrams of progeny per milligram of parent. Many of the results were subjected to statistical analysis.Some of the findings indicated by the general biological observations made, and by the several statistical interactions manifested, were the following. Though the different types of weevils were differently affected by being reared on different kinds of grain, all types were adversely affected by being reared on white rice. The response of the different types of weevils to a rearing temperature of 31 °C varied with the kind of grain and type of weevil, and, in one type, was associated with loss of mycetomal microorganisms. In contrast, a type of weevil (MW) normally free of mycetomal microorganisms at 27 °C was less affected adversely by being reared at 31 °C than the corresponding type (GG) normally harboring them. It is suggested that, in precise work with these weevils, investigators should determine with which strain they are working. Cause and effect are discussed. It is suggested that no single index can adequately express simultaneously both the quality and quantity of a population.

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