| Asian corn borer,Ostrinia furnacalis(Guenee),Yellow peach moth,Conogethes punctiferalis(Guenee),Cotton bollworm,Helicoverpa armigera(Hubner),and Oriental armyworms,Mythimna separata(Walker)are the main Lepidopteran insect pests of maize in Huang-Huai-Hai maize planting area,some of which usually infect the same tissue or organ concurrently at different development stages of maize.In order to understand the occurrence and ecological niche of these main Lepidopteran insects on maize,we investigated the spatial-temporal distribution of the four Lepidopteran insect of maize in Langfang,Hebei Province,and measured the niche and interspecific competition coefficient on maize.The main results are as follows:1.M.separata only infests maize leaves before the milking stage.O.furnacalis could damage maize plants through the whole growth period,and the older larvae bore into all parts of maize,both ears and stalks.H.armigera feeds on maize plants in all growth period and only damages the maize ears at the ear stage,which also injures the maize leaves before the ear period.C.punctiferalis can only be observe on the ears and in the upper and middle parts of stalks after the blister stage.2.These four species of Lepidopteran insects occur explosively at different developmental stages,and they had interspecific competitions in the time dimensions.The interspecific competition coefficient between O.furnacalis,H.armigera and C,punctiferalis is greater than 0.95,so they had intense interspecific competitions in the space dimensions.3.Temporal niche breadth of M.separata is the narrowest,therefore,M.separata is most likely to cause serious damage while influenced by the changes of biotic and a biotic factors.Niche breadth of O.furnacalis is the widest,so it is least affected by the external environment and has the maximum probability to survive in maize.4.Among the main Lepidopteran insect pests of maize in Langfang,O.furnacalis is the most harmful dominant species,which does infest maize for the longest time,M.separata only damages maize leaves before the milking stage,while the population of O.furnacalis,H.ar,rmigera and C.punctiferalis increase sharply after the blister stage,and the population size is larger than that before,respectively.Particularly,the population size of H.armigera and C.punctiferalis are even larger than that of O.furnacalis during the ear period in summer maize.Therefore,predictions should be made timely before the blister stage.If the maize damages by these lepidopteran insects is not serious before blister stage,it would be a good choice for control H.armigera,C.punctiferalis and M.separata while we control the O.furnacalis at the same time. |
