Studies On The Dynamics Of Arthropod Communities And The The Relations Of Pests With Their Natural Enemies In Pear Orchards

The thesis came from the project"Special Fund of Anhui Province Governor (y47)—integrated pest management and application for the non-environment damage vegetables". The dynamics of arthropod communities in pear orchards and the interaction of main pests with their natural enemies were studied though systematic investigation on pear orchards in Anhui University science demonstration.This will provide theory foundation for IPM of pests lived in pear orchards.1 The arthropod total community was divided into phytophage, predacious, parasitic - neutrality sub-community according to species'nutrition and predator-prey relationship. Components of the total and sub-community were analyzed by number of groups, individual numbers and some other ecological indexes. In 2007, 38 species arthropods were got which belonged to 33 families. The relative abundance of pytophage was 82.34%, the dominant species was Stephanitis nashi; and that of predacious sub-community was 13.21%,the dominant species were Erigonidiumg raminicola and Harmonia axyridis. the dominance was indicated that phytophages sub-community(0.5580) >total community (0.4595) >predacioussub-community(0.4423), and diversities indexes was total community (2.7730)> predacious sub-community(2.3338) > phytophage sub-community(1.9519).2 Caused by interaction of pest with its natural enemies and climate factors, indexes of every community fluctuated up and down. Diversity index of total community change gradually in pear orchards, the total community have the low–high-low-high-low tengency. The diversity index H'was determined by the species and individual numbers.The dynamic changes of evenness and diversity index of community have the same tendencey basically. On change tendencey, individual numbers is similar to the species richness degree,but the dominant is nearly contrary to diversity index.3 Total community,phytophage and predacious sub-community in different time was analyzed by clustering.The result indicated that when clustering D was 1.9704,the total community could be divided into 4 clusters;so did the phytophage sub-community when D was 1.4779;the predacious sub-community could be divided into 4 clusters when D was 1.5771.From the four paterns,wecould know that the community had a start, stable,outbreak and recession experience. The result of the optimization partitions in the arthropod communities was that changes of community according to time could be divided into four stages: April 11-May 23; June 6- July 17; August 1- November 7; November 21. 4 The characteristic parameters of arthropod total community and its phytophagous,predacious sub-community in pear orchards were analyzed with the method of principal component analysis. The results showed that the contribution in the second principal component of arthropod community and phytophage sub-community was 86.03% and 88.58%, the contribution in the third principal component of predacious sub-community was 86.95 % . Standard of regression coefficients︱bi︱was used to compare to contribution of different index. For the three kinds of communities, the absolute values of normalized regressive coefficient of N,S,R and H'had greater contribution.5 To use and conserve reasonably natual enemies,the quality,time, and spatial frame work of Stephanitis nashi and its natural enemies was studied using regression analysis, grey system analysis, ecological niche analysis and aggregated-intensity index analysis of spatial patterns. The order of natural enemies which were close relationship with Stephanitis nashi was Erigonidiumg raminicola,Harmonia axyridis,Tetragnathae, Therdionoctomaculatum,Chrysopa sinica and Misumenops tricuspidatu at quality;The order of natural enemies which were close relationship with Stephanitis nashi was Tetragnathae,Misumenops tricuspidatu,Erigonidiumg raminicola,Harmonia axyridis, Chrysopa sinica and Therdionoctomaculatum at time;The order of natural enemies was Harmonia axyridis, Erigonidiumg raminicola, Misumenops tricuspidatu, Chrysopa sinica, Therdionoctomaculatum, and Tetragnathae at spatial frame work.6 In order to carry out the integrated pest management for the pest, pesticide Haoniandong and Jindianzi were used spraying pear threes on November 9,2007.Control effects Nippolachnus piri Matslumura of Haoniandong was 77.20%,87.54%,87.21%,90.09%,84.50%,85.27%,1 day,3 days, 5 days,7 days ,9 days ,14 days after spraying pesticide.That of Jindianzi was 69.39%,72.93%,49.16%,80.04%,61.52%,56.20%.The comparation of two pesticide was that effect was obvious after 1day spraying and extremely obvious after 7days spraying,the comparation was extremely obvious from 1day to 14days. Diversity index arthropod in pear orchards was increased because of the death of aphids and Haoniandong had a greater interference to community.