Studies On Host Selection And Its Mechanism Of A Parasitoid Wasp, Tetrastichus Sp. (Hymenoptera: Ichneumonidae)

Tetrastichus sp. is an important ectoparasitoid wasp which parasitizes nymph of the wolf-berry psyllid, Paratrioza sinica Yang et Li. which is one of the important pest of Lycium plant. Many parasitoid wasps can be breeded artificially and released in the field to control the pests-damage. However, Tetrastichus sp. can't be breeded artificially yet. For the reason, it's important to ascertain the allelochemical which the wasp utilize in the course of host-seeking, consequently, provide theory basis for practice of allelochemical using. The allelochemical which affects the parasitoid behavior of Tetrastichus sp. was studied with four-arm olfactometer and Petri dishes. The results showed that female wasps responded significantly and positively to nymphal secretion.Liposoluble components of the secretion were identified by Gas chromatography mass spectrometer(GC-MS). The major components are hydrocarbons, hydroxybenzene and benzene. Amino acids in the secretion were analyzed by Amino Acid Analyzer. There are 16 different kinds of amino acids identified and 15 kinds of free amino acids except arginine in the nymphal secretion. The total content of soluble sugar in the secretion is 7.88% .The behavior responses of the female wasps to different kinds amino acids were tested in Petri dishes. The results showed that only 3 of 13 amino acids tested, elicits the searching behavior of Tetrastichus sp. significantly. Olfactory behavioral responses of Tetrastichus sp. to liposoluble components of secretion were studied with a Y-tube olfactometer. It showed that female wasps were significantly attracted by 0.76% n-C14 , 1.52% n-C14, 1.84% n-C17 and 0.49% n-C18 (P<0.01). Attractive effects of 0.76% (+)-Longifolen, 1.52% Isolongifolene, 1.14% n-C20, 2.28% n-C20 , 1.22% n-C21 and 0.62% n-C22 on female wasps were lower compared with the former four (P<0.05). Female wasps were repelled by the volatile of 0.76% n-C9, 0.64% n-C13 , 1.96%n-C18 , 0.53% n-C19 and 1.24% n-C22, Benzrthiazole, n-C11 and n-C16 have no effects on the olfactory behavioral responses of female wasps no matter what concentrations they were. 0.49% n-C18 and 0.57% n-C20 attracted female wasps, but their higher concentrations, 1.96% and 2.28% respectively repelled female wasps. 0.76% n-C14 , 1.84% n-C17 and 0.49% n-C18 were used both in room and field , that...