The Research On Biological Characteristics Of Blattella Germanica And The Operational Mechanisms Of Pyreghtoid

Acting as one of the worldwide dangerous indoor vetor insects, Blattella germanica has fearful invaded our country increasingly since 1990s. Blattella germanica has high reproduction capacity. It is reported that a female can breed 4 generations or more one year under suitable conditions. At present, chemical management is the main method to control this insect, but lasting abundance abuse of insecticides has made the resistant problem badly. Pesticide resistance has been a critical restrictive factor for chemical management of Blattella germanica. The determinative reason is the occurrence and the development of resistance. Research of toxicity mechanism of insecticides and rapid accurate determination methods are the base of the work. It is essential to make some research aiming at the characteristics of biology and toxicology.At first, we studied effects of different feeding density and sex ratio on development of German cockroach reproduction capacity in bionomics. We used the susceptible strain from Shandong Center for Disease Control and Prevention. We set up five different densities and three different sex ratios and studied the effects of two factors and interaction. Observed and noted mating, oviposition, hatching, the weight of the first age larva and sex condition at different feeding density and sex ratio. Second, we studied the operational mechanisms of permethrin on Blattella germanica in toxicology. We first determined LC50 and than determined five low lethal concentrations of permethrin that their lethal rates were not more than 35% through many experiments. We tested acetylcholinesterase (AChE), catalase(CAT) activities of susceptible strain when we sprayed quantitative permethrin of different concentrations on them for 24hours, 48hours, 72hours, 96hours and 120hours, with the responding of polyacrylamide gel electrophoresis(PAGE). We could thoroughly research the operational mechanisms of permethrin and the dosage effect and the time effect correlation between permethrin and different enzymes activities of Blattella germanica. Third, resistant strain were compared with susceptible strain, we observed the difference of AChE and CAT activity between the two strains and their isoenzymic band. We discussed the senses and utilization of the indexes of molecule toxicology in factual resistant monitoring.The results showed that density restrain effect became evidently as the increasing of population density under the limited resource of space and food. As the increase of density, the hatchability decreased, the weight of the low-age larva became decreasing tendency. The relationship between weight and feeding density met the logistic equation. When the feeding density increased to a certain degree, the offspring number of one female decreased slowly as the increase of feeding density, kept certain range. It showed Blattella germanica had certain self-protected ability and could keep certain reproduct capacity. The life time of Blattella germanica is 80 day by simulation experiment in the lab. It could reproduct 3～4 generations one year under suitable conditions.At toxicology aspects, the results showed that permethrin had apparently inhibitory effect on AChE and the results showed the dosage effect and the time effect correlation between them. It also had inhibitory effect on CAT, although the role was disordered. Under different concentration medication, the light of the EST and CAT band and expression quantity were different. It showed that we must consider insecticide resistance and pesticide tolerance questions when we use permethrin. We should reasonablely control insecticide concentration of our using and scientifically establish spraying time in order to prevent resistance of Blattella germanica and prolong usable life of insecticides.The results showed that AChE activity had significant difference between resistant strain and susceptible strain. Isoenzymic band showed EST not only expression quantity but also quality was different between two strains .Compared with susceptible strain, resistant strain added a band. CAT activity had little difference between two strains, isoenzymic band had only different expression quantity. EST was effective indexes of resistant monitoring in factually resistant monitoring. CAT can only be reference indexes and need more research. The research in effect of density and sex ratio on the reproduction capacity of prolificacy pest such as Blattella germanica, and that of the operational mechanisms to permethrin which is the represention of pyreghtoid and widely used at present, may perfect and enrich the research information of biology and toxicology on Blattella germanica, so both of them had important academic senses and actual application value. At the same time, the research of resistant monitoring on molecule toxicology indexes offered fast, expedient and exact methodological reference. Furthermore, the study discussed the management policy which could effective control the population density on Blattella germanica against the harmful status on Blattella germanica.