| Tetranychus cinnabarinus and Tetranychus urticae are a kind of serious agricultural pest,which distributed widely in China.It harms seriously cotton,peanuts,beans,mulberry,flowers,vegetables,fruiter and other crops,resulting in yield reduction and quality degradation.Peanuts are an important oil crop in Shandong Province,but spider mites have caused the serious harm to the economic value of peanuts in recent years.At present,the control of this kind of pests mainly depends on chemical agents,and physical control methods are scarce.Mulching films can increase crop yield by changing soil temperature and humidity,and affect the occurrence of pests too.However,there are few studies about the effects of mulching films on the occurrence of pests.Based on the discovery that the colored films can prevent insects and increase production of crops,there researched the characteristics of the effects of peanuts covered with 4 kinds of colored mulching films on the occurrence of spider mites and explores its mechanism.The characteristics of colored films that have an effect of increasing yield on peanuts are described.To provide a theoretical basis for the physical control of spider mites and high yield of peanut.And the main results are as follows:1.We found that the occurrences and damage degree of spider mites were significant differences in 4 peanut fields covered with different colored films.Silver black and silver gray mulching films significantly reduced the occurrence of spider mites with the number of 18.56-24.92 and 32.48-35.76 individuals/plant,and transparent films was 65.16-73.28 individuals/plant.It was found that the dominant species of the spider mites in the main peanut producing area of Shandong Province was T.cinnabarinus.In recent years,T.urticae was more and more harmful.It often occurred in combination with T.cinnabarinus,but its occurrences was significantly less than that of T.cinnabarinus.2.The results of selection test showed that,compared with the transparent mulching films,T.cinnabarinus and T.urticae showed the highest selectivity to silver gray and silver black films.Under the condition of simulated natural light,T.cinnabarinus showed the lowest selectivity to silver gray films witch was 5.60%,followed by the silver black films which was 14.43% after 48 hours,significantly lower than transparent.T.urticae showed the lowest selectivity to silver gray films,followed by the silver black films,significantly lower than transparent.Compared with the transparent films,the silver gray films could significantly inhibit the population growth of spider mites,followed by the silver black films.The number of T.cinnabarinus of silver grey and silver black was 817.00 and 860.00 individuals/plant after 14 days,which was significantly lower than transparent.The growth trend of T.urticae on 5kinds of colord films was basically the same as that of T.cinnabarinus,but the growth rate is slower than that of T.cinnabarinus.The oviposition of the leaves growing under the silver gray and silver black films decreased and the development period increased.3.The spectral reflectance of different colored films was different,silver gray films has the highest spectral reflectance,followed by silver black films.The UV-B,UV-A and green spectral reflectance of the silver gray and silver black films were significantly higher than those of the transparent films.The total spectral reflectance of black films was lower than that of the control.It was found that UV-A and UV-B had different effects on the two spider mites.T.cinnabarinus had obvious repellency to UV-B(wave peak 315nm),and the repellency rate of 400 lux was significantly higher than that of 200 lux,UV-A and green were not different from visible light.There was no significant difference in the repellency rate of T.urticae under UV-B spectral light intensity,but the repellency rate of T.urticae at 400 lux was significantly higher than200 lux under UV-A.4.The hatchability of T.cinnabarinus and T.urticae were lower under UV-B and UV-A spectrum,and the hatchability of T.cinnabarinus under high light intensity was significantly lower than that under low intensity.However,the hatchability of T.urticae was low under two light intensity,and there was no significant difference between them.The fecundity of T.cinnabarinus in UV-B spectrum decreased significantly,the number of eggs was only 7.25 per female,and the light intensity had no effect on its fecundity.The fecundity of T.urticae in UV-B and UV-A was decreased was significantly less than the fecundity in visible light.And the light intensity has effects on the amount of oviposition.The amount of oviposition under high light intensity was2.70 and 3.80 per female,which was significantly less than that under high light intensity.5.Compared with transparent films,the yield of silver black films and silver gray films increased significantly,and the effect of silver black films was the most obvious.The yield of silver black and silver gray films was 17.05% and 15.68% compare with transparent films.The weight of 100 fruits of silver black and silver gray films was significantly higher than transparent films.And the kernel rate was 76.44% and 75.98%respectively,which was significantly higher than 69.34% in transparent films.Silver black and silver gray films increased the weight of 100 fruits and the rate of kernel production,which was an important reason for yield.Covering with silver black and silver gray films can reduce the number of needles in the soil,and reduce the number of ineffective needles in the later stage of peanut.And the number of young fruits significantly lower than the transparent films.The main stem diameter of peanut covered with silver gray and silver black films increased significantly in the whole growth period compared with transparent films.In this study the yield of films with0.018 mm was the highest,the second was films with 0.014 mm,and the yield of films with 0.006 mm was the lowest.6.There were significant differences in nutrient and metabolite levels of different colored films in flowering stage.The content of chlorophyll and soluble sugar in silver gray and silver black treatments were higher than that of transparent treatments,which was 17.55 spad,18.34mg/g and 20.14 spad,23.22mg/g respectively,and that of transparent films was 15.67 spad and 15.45mg/g.The content of total phenols was higher than that of transparent treatments,which was 26.39mg/g and 28.00mg/g,and transparent films was 22.82mg/g.However,there was no significant difference in flavonoid content between treatments.There was no significant difference between black film and transparent film. |
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