【摘要】 本工作选用棉花不同器官所含有的几种化学成分作为嗅觉和味觉刺激剂,测验棉铃虫对它们的反应;结果表明一至三龄的幼虫对甲醇三甲基胺、香草酸等的趋性不同,四龄幼虫对不同的糖类、氨基酸等的取食反应也各不一。这说明幼虫对食料植物中的个别化学成分有感觉辨识的能力。用不同品种的海岛棉、陆地棉、以及棉花和其它锦葵科植物杂交所产生的后代的叶片来试验棉铃虫对它们的趋性和取食反应,结果表明当有选择的机会时幼虫对陆地棉和一定品种海岛棉有较强的趋性,对某些杂交后代的趋性很弱。在不能选择的条件下棉铃虫在一定时间内对不同种类或品种的棉叶的取食量也不相同,并对原来的食料植物可形成条件化。 曾对棉花不同器官的含水量、含氮物质和糖类进行了测定,同时分别用叶、蕾和铃将新孵化的幼虫饲养到老熟。幼虫取食不同器官时的累积食量、发育速度、死亡率,和变成的蛹的重量均有明显的差别。当以大叶为食时幼虫的总食量超过以嫩叶为食时的一倍以上;以铃为食时总食量可为以嫩叶为食时的数倍。这种差异可能是因铃中水分和含糖量较高,对幼虫的取食发生强烈的助长作用所造成的。因此,同株植物上含糖和含水缺多的器官对棉铃虫似乎有较好的营养效应,而这种效应可能是通过糖类等的味觉刺激来增加取食量所造成。更多还原

【Abstract】 In order to test the tactic response of the cotton bollworm, Heliothis ammigera(Hubner), to the odors of its preferred host plant, certain volatile substances known tobe present in the cotton plant such as methanol, trimethylamine and vanillic acid werechosen as olfactory stimulants. It was found that the larvae in the early three instarswere attracted by the vapors of vanillic acid and trimethylamine in various degrees, butmethanol vapor had a repellent effect. These vapors were emitted from aqueous solu-tions at the concentrations of 0.006 M 0.02 M and 0.03 M respectively. By using thesugars, free amino acids and vitamins which were shown to be present in the cotton plantas gustatory stimulants and incorporating them separately in the agar-based media, it wasfound that at the concentration of 0.02 M sucrose and fructose had a definite phago-stimulating effect, glucose was less effective, and xylose was indifferent. At low concen-trations, only DL-alanine among the five amino acids tested had some phago-stimulatingeffect, and ascorbic acid at 0.01 M was phago-inhibitive. These results show that thecotton bollworm as a polyphagous species responds differently to the individual com-ponents of the host plant which may act either as attractants or repellents, phago-stimulants or phago-inhibitors. Different species and varieties of cotton plants and some descendants from thehybridization between cotton and some other malvaceous plants such as Hibiscus palus-tris,H. mutabilis, Malva sylvestris and Althaea rosea were used to test the tactic andfeeding responses of the cotton bollworm. It was found that when the larvae had thechance to choose their food, they were more readily attracted to the leaves of Gossypiumhirsutum and certain variety of G. barbadense, but not so readily to some of the hybriddescendants, some of which may even show repulsive properties in the test. In thisrespect different varieties of H. barbadense also had different effects. When there wasno chance to choose their food, the larvae were observed to consume different quantitiesof foliage from different plants in a definite period of time and to become conditionedto the host plants with which they were brought up. Simultaneous chemical analysis showed that the water content as well as the total andprotein nitrogen contents of the cotton leaves gradually decreased as growth proceeded.The total nitrogen content also dropped when the squares developed into flowers, andthe protein content was found to reach the maximum when the squares had attained alength about 2.5 cm. The total and protein nitrogen contents of the bolls dropped asthe latter grew and aged. The total and protein nitrogen contents of the leaves seemedto be the highest as compared with those of the squares and bolls. The quantities ofsoluble and reducing sugars of the young leaves exceeded those of the tender and oldleaves, but the sugar contents of the bolls were found to be much higher than those ofthe leaves. The sugar contents of the squares were relatively low. In spite of these disparities, it was possible to grow the larvae after hatching into maturity separately andsolely on the leaves, squares and bolls of the cotton plants. In these rearing experi-ments, the cumulative quantities of food consumed, the rates of development and mor-tality, and the weights of pupae thus obtained were found to be conspicuously different.It is interesting to note that the larvae during the whole course of development wouldconsume the old leaves to an amount which may double the total quantity of the foodconsumed when the young leaves were offered. When the bolls were used as food thecumulative quantity consumed exceeded several times that when the leaves were used.This difference is presumably attributed to the differences in the water and sugar con-tents of the different organs of the cotton plant, as already shown that sugars usuallywould evoke a strong phago-stimulating effect. The general impression is that the plantorgans which have the higher sugar and water contents usually have a better nutritiveeff更多还原