Control Effect Evaluation Of Non-host Plant Intercropping Against Colorado Potato Beetles

As an important part of pest ecological regulation,farmland crop layout has always been a research hotspot of protective biological control.In order to further clarify the impact of non-host planting intercropping on Colorado potato beetle population dynamics,new ideas and methods for sustainable control of Colorado potato beetles were explored.In this study,two types of potato-sunflower or corn intercropping and potato-corn intercropping in different rows and potato-calendula intercropping were investigated in the field population during Colorado potato beetle occurrence,and the differences in population dynamics of Colorado potato beetles were analyzed and compared under different planting patterns.The study obtained the following main results:(1)Effects of intercropping sunflower or maize on Colorado potato beetle population and its natural enemiesThe results showed that the peak of the first generation adult larvae was earlier than the two intercropping modes,and the peak period of the second generation of potato monocropping larvae appeared later than the two intercropping modes.During the low peak period of the second generation larvae(August 26-September 7,2018),the amount of potato-corn intercropping larvae was significantly lower than that of potato monocropping(P<0.05).And the amount of potatocorn intercropping larvae was significantly lower than that of potato monocropping(P<0.05).During the whole investigation period,the amount of potato monocropping was larger than that of two intercropping.Besides,surveys of natural enemy insect communities showed that the amount of Harmonia axyridis in intercropping corn was significantly higher than that in potato monocropping(P<0.05)and the amount of Syrphidae and Chrysopidae in intercropping corn was higher than that in potato monocropping.Intercropping sunflower or corn affects on the spread of wintering Colorado potato beetles.Interplanting sunflower or corn during the early sowing period can block the colonization and spread of Colorado potato beetles to a certain extent.(2)Effects of intercropping maize with different row ratios on Colorado potato beetle population and their natural enemiesAt the peak of the first generation of older larvae(June 28-July 19,2019)and the first peak of the young larvae(July 26-August 16),the single crop field was old The number of larvae was higher than the three intercropping fields,and the difference was not significant.At the peak of the first generation of adult pests(July 12-August 2)and the low-peak period of the first generation of adult pests(August 2-August 23),the number of adults in single cropping fields was higher than there were no significant differences among the three intercropping fields.During the entire investigation period,the number of worms in the three types of potato intercropping fields was less than that in the single cropping fields,as far as the larvae and adults were concerned.Also,surveys of natural enemy insect populations in three intercropping fields showed that the average insect pest of the dominant natural enemies,Adonia variegata was higher in potato-corn 4:2 intercropping fields than in potato-corn 2:2intercropping fields,and the differences were significant(P<0.05).In the later period of potato-maize intercropping,the number of Colorado potato beetles in the intercropping field was lower than that in the monocropping field.(3)Population dynamics of Colorado potato beetle under intercropping of calendula officinalis and chemical controlTrap control experiment:Through the analysis of this part of the test data,it cannot be concluded that the intercropping of marigolds directly affects the population dynamics of Colorado potato beetles.Chemical control experiment:In the larval population,the experimental field in Zhongliang village after July 12th,due to the application of the pesticide on July 12,the larval population decreased significantly,and the rate of worm mouth decline reached 86.79%.Among the adult populations,the peak period of the first generation of adult worms in the experimental field of Zhongliang village was from July 26 to August 2,and the number of adult populations did not decrease significantly.What is clear is that the 30%fluorin-indoxacarb-suspension has better control effect on Colorado potato beetle larvae and can effectively reduce the population of larvae.