Effects Of Maize-Mung Bean Intercropping Patterns On The Occurrence Of Pests And Natural Enemies On Maize And Mung Bean

Our experiment was designed with 7 maize-mung bean intercropping treatments such as 2:2 treatment(two rows of maize and two rows of mung beans),4:2 treatment(four rows of maize and two rows of mung beans),6:2 treatment(six rows of maize and two rows of mung beans)and their random treatment of the above three(random 2:2,random4:2,random6:2),mung beans surround the outside planting of maize.The main pests and natural enemies on maize and mung bean were investigated at 4 key growth stages of maize(flare opening stage,grain-filling stage,milky maturity stage,maturity stage),number of 3 species of lepidopterous pests on maize ears with different intercropping treatments were surveyed;Based on the principles and methods of community ecology,the characteristics of arthropod communities in different intercropping treatments were analyzed,and the yield of maize in different intercropping treatments was measured.The main findings are as follows:1.According to the survey statistics,among the lepidopterous pests in different treatments,Ostrinia furnacalis mainly occured at the maize milky maturity stage,and the maximum number of the Ostrinia furnacalis larvae can reach 85 individuals per hundred plants(blank control).The 2:2 and 4:2 treatments had a high parasitic rates of egg masses and a small number of Ostrinia furnacalis.The occurrence of Helicoverpa armigera was large at the grain-filling stage,and the regulation effect of each intercropping on Helicoverpa armigera was not obvious,but the effect of 2:2 treatment was better.The occurrence of Conogethes punctiferalis was later than that of the Ostrinia furnacalis,and the occurrence rate peaked at the milky maturity stage,no better intercropping treatments were found in control of the pest.2.In two consecutive years(2018~2019)of investigation in maize and mung bean communities,there were 53 species of pests and natural enemies belonging to 1 phylum,2 classes,9 orders,and 33 families in 2018.There were 26 species of pests,and the dominant species were the lepidopteran borer pests such as Conogethes punctiferalis,Ostrinia furnacalis,Helicoverpa armigera and so on.There were 27 natural enemies,and predatory natural enemies are dominant natural enemies' group,dominant species are Hylyphantes graminicola,Coleosoma octomaculatum,Araneidae,Xysticus ephippiafus,etc..59 species belonging to 2 phylums,3 classes,11 orders,39 families were investigated in 2019.There are 29 species of pests,borers such as Helicoverpa armigera,Ostrinia furnacalis,and Conogethes punctiferalis are still dominant pests.There were 30 species of natural enemies,and the dominant species are Hylyphantes graminicola,Coleosoma octomaculatum,Harmonia axyridis,Propylaea japonica,etc..3.Comprehensive analysis of the characteristics of arthropod communities in different intercropping treatments revealed that the individual number and species richness of arthropods communities on maize and mung bean were varied in different trends.The decrease of natural enemies in maize fields in 2018 led to an increase in the occurrence of pests.The increase of natural enemies in maize fields at the maturity stages in 2019 effectively reduced the number of pests.There are similar trends in mung bean fields to that in maize fields.Intercropping treatments with a high community diversity index,such as 2:2 and 4:2 treatments,have higher dominance of the main natural enemies and lower dominance of the main pests.4.The yield of maize in different intercropping treatments was measured,the 100-grain weight of 2:2 treatment,random 2:2 treatment,4:2 treatment and random 4:2 treatment were higher;but the highest yields were obtained in random 4:2 treatment and 4:2 treatment compared with other treatments in 2018 and 2019,respectively.