Investigation On Natural Enemy Insect Resources And Biological Control Of Fall Webworm In Langfang Area (Hebei Province)

Hyphantria cunea Drury is a species of world-wide quarantine pest. Biological control is one of the important means to control its diffusion, spread and damage. In order to use the natural enemy insects to control the Hyphantria cunea Drury effectively, we have carried out a thorough investigation on the natural enemy insect resources and experiment of using Chouioia cunea Yang to prevent and control Hyphantria cunea Drury. The preliminary result as follows:1. The Biological Characteristics of Hyphantria cunea in Langfang area. This dissertation has done some research on the host selection, characteristics of emergence of every generation and life history in Langfang area. In this district, it feed on 34 kinds of trees and it has three generations one year, the peak of emergence in first generation is from May 4 to May 9, and the second generation is pre and post July 16, the third generation is from August 21 to August 30. On different trees in Langfang area, fecundity and hatching rate of the eggs of Hyphantria cunea is different, the maximum fecundity is 975, and most hatching rate is over 90%.2. The Enemy Insect Resources of Hyphantria cunea.There are 11 species of parasitic flies in Langfang area, three of them belonging to Exorista Meigen of Tachinidae, one of them belonging to Pales Robmeau-Desvoidy of Goniinae, one of them belonging to Compsilura Bouche, three of them belonging to Carcelia, two of them belonging to Sarcophagidae, one of them belonging to Phoridae. Such as Exorista fasciata Fallen, Ctenophorocera pavida Meigen, Compsilura concinnata Meigen, Exorista japonica Townsend, Exorista sp1., Carelia sp1., Carelia sp2., Carelia sp3., undetermined species of Sarcophagidae 1, undetermined species of Sarcophagidae 2, undetermined species of Phoridae 1. There are 16 kinds of parasitoid wasps, four of them are Ichneumonidae, three of them are Braconidae, and nine of them are Chalcididae. Such as Aprostocetus magniventer Yang, Tetrastichus litoreus Yang, Tetrastichus shandongensis Yang, Tetrastichus nigricoxae Yang, Tetrastichus septentrionalis Yang, Chouioia cunea Yang, Dolichogenidea ingularis Yang et You, Cotesiagregalis Yang et Wei, Coccygomimus diparis Viereck, Coccygomimus parnasae Viereck, Casinaria nigripes Gravenhorst, Enicopilus sp., Brachymeria lasus Walker, Apanteles ardimarium Ratzeburg, Monodotomerus sp. . And we also find 2 kinds of predators. Such as Parena cavipennis Bates, Himacerus apterus Fab.. We also do a preliminary observation on the parasitic or predation ofevery enemy. 3. The Research on the Adaptability of Chouioia cunea in Langfang area. The highest parasitic rate of Chouioia cunea which we released in the field is 87.00%, and the average is 64.30%. The parasitic rate of the overwinter generation is 51.39% on average. It appears that Chouioia cunea can live well in Langfang area and control the fall webworm effectively.4. Toxicity of Diflubenzuronâ…¢on the Chouioia cunea Yang. Whatever in the part of releasing the wasps before chemical spray or the part of chemical spray before releasing the wasps, all the concentrations of Diflubenzuronâ…¢have no significant effect to the survival of Chouioia cunea Yang.5. Research of Predation of Parena cavipennis Bates to larve of Hyphantria cunea. The Predation equation to the 2 instar larve of fall webworm is f(N)=0.4424*N/(1+0.00672N), 4 instar is f(N)=0.3528*N/(1+0.0208N),and 6 instar is f(N)=0.137*N/(1+0.03109N). The interfere equation is E=0.240268P-1.1444.