Study On Occurrence And Development Law And Prediction Of Common Stored Grain Pests In Grain Bulks

China is a big grain storage country,grain security is very important,and stored grain insect pests is an important factor that endangers food security storage.Therefore,studying the occurrence and development law of stored grain insect pests in grain bulk and predicting the occurrence and development trend of stored grain insect pests can make control measures on pests timely and accurately to avoid large losses of grain.Firstly,the effect of different temperature gradient on the migration and distribution of three stored grain insect pests,including Sitophilus oryzea(Linnaeus)?Rhizopertha dominica(Fabricius)and Tribolium castaneum(Herbst),was studied.Secondly,the occurrence of stored grain insect pests was analyzed by the methods of probe trapping and manual sieving,and the occurrence and development law of stored grain insect pests were studied by temperature nephogram and humidity nephogram and linear regression.Finally,built a model about the development trend of stored grain insect pests in the grain house based on the artificial neural network theory,which can predict the numeber of stored grain insect pests for a period of time in the future,so as to analyze the occurrence and development law of stored grain insect pests in the grain house.The main research results are as follows:1.The migration and distribution of stored grain insect pests under different temperature gradients in grain bulkSetting different temperature gradients on opposite sides of steel bins filled with rice: 25°C~30°C,20°C~30°C,30°C~30°C,20°C~35°C,to studied the migrant and distribution of three stored grain pests including T.castaneum adults,S.oryzea adults and R.dominica adults,the results showed that the distribution trends of adults of T.castaneum,S.oryzea and R.dominica in a certain grain temperature gradient had significant difference(p < 0.05).The distribution of S.oryzea was consistent with the quantitative distribution of T.castaneum in the grain bulk with a certain temperature difference except at the grain storage temperature gradient of 25?-30?,they all tended to gather in the areas with higher grain temperature.The R.dominica tended to gather in the areas with lower grain temperature in the grain storage temperature range of 20?-30?,and when the grain storage temperature was higher than 30?,it tended to gather in the areas with higher grain temperature.After cooling,the R.dominica stayed in the peripheral area of the grain storage under the influence of low temperature,and there was no obvious trend for T.castaneum,and the S.oryzea tended to migrate to the center of the grain storage with higher temperature.2.Research on the law of the occurrence and development of stored grain insect pests in grain houseSix kinds of stored grain pests were detected by probe trap and manual sieving,including Liposcelis bostrychophila(Badonnel)?Tribolium castaneum(Herbst)?Sitophilus zeamais(Motschulsky)?Cryptolestes ferrugineus(Stephens)?Sitotroga cerealella(Oliver)and Typhea stercorea(L.),among which L.bostrychophila was the dominant species,accounting for 89.68% of the total capture number of stored grain insect pests.In the early stage of development of stored grain insect pests,the method of probe trap can detect the occurrence of stored grain insect pests earlier than manual sieving.The number of insects trapped by probe trap was much larger than that by manual sieving at all detection points in the grain house.Most of the stored grain insect pests were detected in the central,eastern and southern areas of the grain house,with the largest capture quantities in the central area that account for 18.47% of the total capture quantities of stored grain insect pests,and the least capture quantities in the northwest corner of the grain house that account for 4.67% of the capture quantities of stored grain insect pests.The distribution area of stored grain insect pests corresponded to the results of temperature nephogram and humidity nephogram analysis.The stored grain insect pests occurred more serious in the areas with higher temperature and humidity.Linear regression equation for each detection point was shown in Table 3-3.The order of slopes was: south > southeast > central > east > southwest > north > northeast > west > northwest.Means the growth rate of stored grain insect pests in the south side of the warehouse with higher temperature and humidity was higher than that in the north side.The slope of the northwest corner of the grain house with lower temperature and humidity was the smallest,and the growth rate of stored grain insect pests was the slowest.3.Prediction model of occurrence and development trend of stored grain pestsA prediction model of occurrence and development trend of stored grain insect pests based on artificial neural network theory was established.The model was simulated and analyzed by MATLAB 2016 a.The database was established with temperature and humidity data and pest occurrence quantity obtained from the grain house.After data normalization standard processing,the model was trained and studied with the experimental data in the database and the structure of the neural network model was determined,and the pest occurrence quantity was predicted.The average accuracy of this model was 89.44%.The model can accurately predict the occurrence and development trend of stored grain pests.