Study On The Tropism Of Black Cutworm Larvae To 4 Kinds Of Plants

The black cutworm is a kind of underground severe pests,and its larvae are extremely widespread.This study first designed a trap to study the tropism of underground pests based on the living habits of the cutworm larvae and then checked the underground pests in this way.Based on of the tropism trap,the field experiment of the influence of two repellent plants mint and marigold in this trap on the feeding tropism of the 3rd instar larvae of the black cutworm under the control of corn and soybean was deeply explored.The "Y" type olfactory instrument was used to test the tactical response of four plants,mint,marigold,corn,and soybean,to the 3rd instar larvae of cutworms.Through this experiment,we understand the response law of repellent plants to the tropism of cutworm larvae.It aims to provide a reference for the effective control of cutworms.The results of the research are as follows:(1)Aiming at the shortcomings of the existing technology,a trap for studying the tropism of underground pests is designed.This trap is low in manufacturing cost and easy to operate.This trap is made based on the model principle of the "Y" type olfactory instrument and because the cutworm larvae are underground pests.There are three barriers in the trap to prevent the cutworm larvae from climbing up into the trapping trough and then returning in the same way,which significantly improves the trap’s accuracy for testing the tropism of the cutworm larvae.(2)In order to study the effect of the repellent plants mint and marigold on the tropism of cutworms,based on this trap for studying the tropism of underground pests,mint and marigold and two control plants,corn and soybean,were mint × corn,Peppermint×soybean,marigold×corn,marigold×soybean,marigold×mint,corn×soy are mixed and planted in the two vertical traps of the cutworm trap,and the insects are caught at the entrance of the trap below 30,observe the distribution of cutworm larvae in the trap and each experiment was repeated three times.The results showed that the two repellent plants,corn and soybeans,which are repellent plants and cutworm larvae,have an extremely obvious influence on the tropism of cutworm larvae.Peppermint and marigold have significant selectivity for cutworm larvae.Lower than corn and soybeans.In terms of attracting rate,corn is more fantastic than mint,and mint is less than marigold.It is concluded that the tropism ranking of cutworm larvae is corn>soybean>marigold>mint.(3)In order to verify the accuracy of the trap in the study of the tropism of the cutworm,a "Y" olfactory instrument was used to test the selectivity of the third instar larvae of the cutworm to mint,marigold,corn,and soybean in the room.4 plants were mixed in pairs and four plants and blank control were used to test the tropism of cutworm larvae to 4 plants.The results showed that the attractiveness of corn and soybean to cutworm larvae was extremely significant than that of two repellent plants,mint and marigold,In contrast corn was more attractive to cutworm larvae than soybean,and marigold was more pieasing to cutworm larvae.Significantly larger than mint.It is concluded that their tropism ranking is corn>soybean>marigold>mint,which is the same as the result of the trap test.