Studies On The Attractancy And Toxicity Of Castor Bean To Holotrichia Oblita

This paper does researches on the major underground pests—white grubs that damage the crops seriously in henan province and some regions all over the country, in order to control the pests on the ground instead of underground, based on the relation of insect and plant, and insect chemical communication, some preliminary works about attracting and toxic of castor bean were conducted both in laboratory and in the field, and the main results are summarized as follows:The selective response of holotrichia oblita to different plants in the field. We found in the field that the number of bettles near the castor bean was bigger than the peanut and cotton, and the difference between the two was siginificant. The result showed a attracting activity of the castor to holotrichia oblita.The attracting activity of different castor leaves in the field. There are holotrichia oblita and other kinds of beetles caught by castor leaves. The holotrichia oblita caught by castor leaves is 97% of the total number, clearly different from the attracting results of simulating leaves and soybean leaves, 0 and 1%. The simulating leaves only caught 0 holotrichia oblita per leaf in verage, and soybean leaves 0.02, but 1.65 beetles were trapped by castor leaves. The result suggested that castor leaves were active to holotrichia oblita. So the result provide a theory basis to control beetles in practice using castor bean.The selective response of holotrichia oblita to different plant leaves. The number of beetles caught by castor leaves are highly more than filter paper, peanut, soybean, elm, creb grass, corn, poplar, willow, apple, peach, annual meadow grass, plum leaves. The difference between castor leaves and the other materials was siginificant. The result showed that the castor leaves were highly active to holotrichia oblita.Volatiles from leaves of castor bean were extracted by steam distillation and methylene dechloride and further identified by gas chromatography-mass spectrometrya (GC-MS). The volatiles of components are made of 117 compounds, among 50 components are identified and the major component, dibutyl phthalate which relative content is 22.6%; and volatiles of components are complicated, including of green leaves odor compounds, aromatic compounds, aldehhydiccompounds, alcoholic compounds, ketonic compounds and some heterocyclic compounds and so on. Some components such as phenol, benzaldehyde, 3-hexen-l-ol, benzene acetaldehyde, benzoic acid, ethyl ester, acetic acid, phenylmethyl ester, caryophyllene, 3,7-dimethyl-l,6-octadien-3-ol, (+)-alpha-terpineol and phytol that were proved to be existed in many plants.The selective response of holotrichia oblita to different plant volatiles. Volatiles from castor leaves , extracted by steam distillation and dichloromethane, strongly attractec female and male holotrichia oblita in the Y-tube olfactometer bioassay, but were less attractive to other 8 test materils, including dichloromethane, peanut, elm, poplar, willow, apple, peach. The result showed that plant volatiles attracting holotrichia oblita contain some active substances which come from castor leaves.The electroantennogram response of holotrichia oblita to the volatiles.(l) The respones to the plant volatiles. The extracts of castor leaves arose larger response of female and male , but there was no significant differerce for castor leaves in comprison to the other plant volatiles. (2) The respones to single compound. To both females and males, the compounds that elicit larger response of holotrichia oblita are 2-phenyl ethyl alcohol, benzaldehyde, phenylacetate, hexanol, cinnamic aldehyde. Benzyl alcohol reveal to have weaker activity. But the females and males showed different response to each compound. The EAG response of males to 2-phenyl ethyl alcohol, benzaldehyde, phenylacetate, hexanol, benzyl alcohol, cinnamic aldehyde were stronger than females. And the EAG response of females to vanllie aldehyde was than males. (3) The response to mixtures. The EAG response of holotrichia oblita to the mixtures showed that SI and S3 were larger than that to single compound. But the females and male showed different response to mixtures. The EAG response of males to S2, S3, S4 were stronger than that of females.And the EAG response of females to SI was larger than that of males.The toxicity of castor bean to holotrichia oblita in the field. We found in the field that some holotrichia oblita near the castor bean exhibited paralysis. The development of paralysis pretented the beetles from leaving the castor leaves to hide. What's more, the number of paralyzed beetles associated with castor was bigger than the peanut and cotton. The difference between castor and the other plant was significant. The appearance of holotrichia oblita which exhibited paralysis was because of consuming the cator. It was know that the peanut and cotton are not toxic...