Studies On The Suitability And Injury Mechanism Of Aphis Gossypii To Its Major Hosts

In this paper, the life table of the experimental population, the differences of figure size and the differentiation characteristics of winged aphids of Aphis gossypii transfered among the three summer hosts of cotton, cucumber and tomato and the lose of amino acids of the host plants injured by cotton aphid were investigated. In the meantime, the different types ,the population dynamics and the biological characteristics of A. gossypii in the three winter hosts of rose mallow, pomegranate and prickly ash were systematically studied. The main results were as follows:1 The life table of the experimental population of cotton aphid in different summer host plantsThe research results showed that the maximal survival time and survival rate of cotton aphid in cotton and cucumber plants were obviously over and above those of cotton aphid in tomato plants. The breeding rate of cotton aphid in cucumber plants was over and above those of cotton aphid in cotton and tomato plants. The isolated female adults of cotton aphid survived 6 days and 4 days respectively after transferred from cotton plants to cucumber and tomato plants and were not able to breed and to establish population during the survival period. The isolated female adults of cotton aphid survived 5 days and 3 days respectively after transferred from cucumber plants to cotton and tomato plants and were not able to breed and to establish population as well. The isolated female adults of cotton aphid survived relatively long time of 7 days and 6 days respectively after transferred from tomato plants to cotton and cucumber plants and both bred on the sixth day after host transfer. This meant that the cotton aphid in tomato plant was probably able to establish population in cotton and cucumber plants.2 The individual characteristics of cotton aphid in different summer hosts under different temperaturesThe research results showed that the body breadth, length and weight of cotton aphid in the same kind of host plant increased with the temperature rising when the temperature was relatively low and reached the highest level when the temperature was 21C. Among body breadth, length and weight of cotton aphid, the body breadth and length decreased relatively slowly and the weight greatly. The weight of cotton aphid in cucumber plant decreased in the greatest range. This was probably because the cucumber plant was relatively sensitive totemperature.3 The determination of amino acid lose of different summer hosts injured by cotton aphidIt was found that the contents of various amino acids of cotton, cucumber and tomato leaves dropped with the population densities of cotton aphid increasing in the plants. There were significant differences between the amino acid contents of CK and the amino acid contents of cotton and cucumber leaves when the population densities of cotton aphid were over 100 heads per leaf. But the amino acid contents of tomato leaves did not decreased significantly until the population density of cotton aphid reached 200 heads per leaf. This meant that tomato plant was more tolerant to the injury of cotton aphid than cotton and cucumber plants.4 The occurrence of the various types of winged aphides in different summer host plants It was found that the populations of pantheress mother and winged female adult were in trend of increasing first and decreasing afterwards and reached the peak level in the first and secondten days of November during the period of the middle October to the first ten days of December. But there was difference in the occurrence time of winged female adult of cotton aphid in different hosts. The winged female adult occurred and reached the peak population level earliestly in tomato plant and about ten days late in cotton and cucumber plants.5 The morphological indices of winged cotton aphid in different host plantsIt was found that the body length and head breadth of winged female adult of cotton aphid in cotton and cucumber plants were nearly same but both of them were greater than those of the...