Abstract: To clarify the species identity and occurrence regularity of main pests and natural enemies in different apple orchards in Zhaotong, we investigated three commonly planting patterns of apple orchards, including natural grass, intercropping soybean, and intercropping alfalfa, by five-point sampling method. The occurrence periods of major pest insects and their natural enemies were divided by the quartile method. The temporal niche index was used to analyze the relationship between the main pest insects and their natural enemies. The results showed that the main pest insects in apple orchards were Aphis citricola, Jacobiasca formosana, and Bactrocera dorsalis, and the main natural enemies were Didea fasciata, Lasiopticus selenitica, Chrysopa sinica, Chrysopa yatsumats, and Harmonia axyridis. Among the three patterns of apple orchards, the longest duration of main occurrence period and earliest occurrence peak of the three pest insect species were recorded in the natural grass orchard. Among the three pest species, A. citricola had the longest duration and earliest occurrence peak during the main occurrence period, with a maximum population density of 124.44 individuals per sticky board on July 19th. D. fasciata had the largest total occurrence number in the three orchards. The population size of natural enemies was the highest in the intercropping alfalfa orchard. The population size of D. fasciata in intercropping alfalfa orchard reached the maximum of 3.22 individuals per sticky board on August 23rd. D. fasciata had following effect on A. citricola, while L. selenitica and C. sinica had following effect on J. formosana. In conclusion, the orchard intercropping with alfalfa is more ecologically stable than orchard with the natural grass, as it is conducive to the reproduction of natural enemies. The main natural enemies in apple orchards have certain natural control abilities to natural insect pests. Our results can provide a reference for the scientific control of insect pests in apple orchards.

Key words: natural grass, intercropping, main occurrence period, niche breadth, niche overlap