Effects Of Colored Plastic Films On The Population Fluctuation Of Aphis Gossypii Glover (Hemiptera:Aphididae) And The Growth Of Cucumber Seedling

With the extensive and rapid development of facility agriculture such as greenhouses and plastic tunnels, the production and application of plastic mulch films in China have been increasing dramatically. Although their effects on crop management received much attention, few studies have considered the effects on insect pests. The aphid, Aphis gossypii Glover(Hemiptera: Aphididae) is one of the most important insect pests of greenhouse plants. In this study, we investigated the effects of five different colored(yellow, blue, red, purple and colorless) plastic films on the developmental and demographic parameters of A. gossypii fed on cucumber plants and cucumber seedling growth potential. The influences of plant morphological and physiological features under the condition of monochromatic light and the effects of monochromatic light on the behavior and biological characteristics of aphids and other herbivorous insects were discussed.1. Effect of colored plastic films on environmental condition in tunnels Colored film changed component of light quality in the tunnels. It showed that yellow, purple, blue and red film improved transmittance rate of the far-red and near infrared light compared with colorless film. Yellow film improved the green and red light transmittance, reduced the ultraviolet and violet light transmittance. Purple film enhanced ultraviolet transmittance, reduced the green light transmittance. Blue film improved the ultraviolet, violet and green light transmittance, and reduced the red light transmittance. Red film improved the ultraviolet and red transmittance, reduced the violet and green light transmittance. The light transmittances of colorless(control), yellow, purple, blue, and red were 80.7%, 78.1%, 67.1%, 84.1%, 64.0% respectively; the mean illumination intensity of 12 o’clock were 5565, 4132, 4003, 4226, 3648 lux respectively. There were no significant differences in temperature and relative humidity in different colored film tunnels due to well ventilated in the tunnels.2. Effect of colored plastic films on life table parameters of A. gossypii The results showed that there were no significant differences in the nymph and adult, as well as total longevity of A. gossypii among the different colored plastic film claddings. The fecundity of A. gossypii in blue and red films was significantly lower than those in purple, yellow and colorless control. The red film significantly decreased the intrinsic rate of increase(r), finite rate of increase(λ), net reproduction rate(R0), and gross reproductive rate(GRR) of A. gossypii compared with the control(Red:r = 0.294,λ = 1.342,R0 = 18.88,GRR=29.24;CK:r = 0.331,λ = 1.391,R0 = 26.41,GRR = 42.12), while the blue film significantly decreased R0 and GRR(Blue:R0 = 19.98,GRR = 31.54). Moreover, both the red and blue films reduced the age-specific maternity and reproductive value of A. gossypii compared with the control.3. Effect of aphid density on population dynamic of A. gossypii in colored plastic film tunnels At the beginning of the experiments, five apterous adult aphids were transferred onto a cucumber leaf, the number of aphids was similar at the same period in colorless, yellow and purple plastic films, but they were higher than red and blue plastic films. When ten apterous adult aphids were transferred onto a cucumber leaf, the number of aphids was highest in yellow plastic film, followed by colorless, purple, blue, and the red plastic film was lowest; when the eleventh day, the number of aphids in colorless, purple, blue and red plastic films reaches a maximum value, then there is a downward trend, but the number of aphids in yellow plastic film was increase. The difference analysis found that the number of aphids was no significant difference between the five colored plastic films when infested five apterous adult aphids. The number of aphids in yellow plastic was significantly higher than those in red plastic film, but was no significant difference with the control when infested ten apterous adult aphids.4. Effect of colored plastic films on the growth of cucumber seedling The stem diameter of cucumber seedlings had no significant difference in different colored plastic films. The plant height and most real leaf area of cucumber seedlings under yellow film were significantly higher than those in control. The plant height and most real leaf area of cucumber seedlings under red, blue and purple were no significantly with control.The plant height, stem perimeter and most real leaf area of cucumber seeding were no significant difference with different aphid density in the same tunnel.