| Cigarette beetle, Lasioderma serricorne(Fabricius),(Coleoptera anobiidae) ,is one kindof cosmopolitan storage insect pests and damages many products, especially the tobacco. Inthis paper, a systemical study was made on cigarette beetle in the respects of diets, pesticidesusceptibility, internal yeast-like symbionts and PH3 fumigation control etc. in order toprovide scientific basis for the effective control of cigarette beetle.1. Effects of different diets on growth , development and reproduction ofcigarette beetle Effects of five diets of kernel, tobacco leaf, cornmeal, liquorice and wheat flour on thegrowth , development and reproduction of cigarette beetle, L.serricorne (F.) wereinvestigated. The duration and survival circumstances of different larva stages and theoviposition ability of adults were observed, and the life table parameters of Ro,rmand λ wereexamined. The results showed the wheat berry,cornmeal and flour were the suitable hosts,and the population trend index (I) were 35.45,39.77 and 32.84 respectively, while thepopulation trend index with liquorice was 7.55 only. The analysis of nutrition ingredients ofthe different diets showed that the soluble sugar contents and protein contents in food werethe significant factors influencing growth and development of cigarette beetle, and the fatcontents in diet were less important . At the same time, the physical characters of granule andpowder of diets were more suitable for the development and reproduction of cigarette beetle.2. Effects of diets on the number of yeast-like symbionts and the development ofcigarette beetle Yeast-like symbionts (YLS) that are biologically important for digestion anddetoxification of insects were found in the alimentary canal of cigarette beetle. The effects ofdiets on the number of YLS and the growth and development of cigarette beetle were studiedwith five diets of kernel, tobacco leaf, cornmeal, liquorice and wheat flour. The resultsshowed that the number of YLS in the 5th instar larva was the highest and the diets hadsignificant influence on the number of YLS in the insects. Cigarette beetle reared by kernelgrew the fastest and had the most internal YLS .There was significant negative relationshipbetween the number of YLS and development, duration of cigarette beetle.3.Effects of diets and symbionts on the susceptibility of insecticides and theactivity of detoxifying enzymes of cigarette beetle The effects of five diets of kernel, tobacco leaf, cornmeal, liquorice and wheat flour werestudied. The results showed that the diets changed the insecticide susceptibility of the larva ofcigarette beetle probably through two kinds of routes. The one was that the diets affected thenumber and activity of internal YLS of cigarette beetle and the other one was the inducedeffect on the activity of detoxifying enzymes (CarE, GstE and AchE). There might be a acrossaction between the above two routes.4. The biological characteristics of the internal symbionts of cigarette beetle The internal yeast-like symbionts (YLS) of cigarette beetle had important effects on thenutrition and detoxification of cigarette beetle. The morphological characters of the cells andthe colonies of YLS were observed and the most suitable growth temperature of YLS wasstudied by determining the number of the colonies, liquid culturing and mensurating the cellqualities. The results showed that 28-35℃ was suitable for the growth of YLS, 35℃ was theirmost suitable growth temperature and 36h-48h was the best time for studying them.5. The interactions between xenobiotics and the yeast-like symbionts of cigarettebeetle The interactions between nicotine, other xenobiotics and the yeast-like symbionts (YLS)Symbiotaphrina kochii Jurzitza ex Gams & von Arx of cigarette beetle, were studied. Theresults showed that xenobiotics such as nicotine, rutin and pirimiphos-methyl etc. can couldincrease the esterase activity of YLS. The order of induced effects was as follows:nicotine-lemon acid salt (172.9%), rutin (146.7%), nicotine (120.6%), pirimiphos-methyl(103.1%). Gel elec...
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