Regulation Mechanisms Of Volatiles Released By Pinus Sylvestnis Var. Mongolica Litv. On A Major Pest Pissodes Validirostris And Its Parasitoid Scambus Punctatus

In this paper, infochemicals collected from the plants Pinus sylveslnis var. mongolica Litv. were firstly identified and analyzed by head-space. Ultrastructures of olfactory receptors of the weevil. Pissodes validirostris Gyll. and a dominant parasitoid wasp in fields. Scambns punctatus. were investigated, and behavioral and electrophysiology responses to volatiles released by Pinus sylvestnis var. mongolica Litv. were also tested.1) Behavioral responses of the weevil and the parasitoid wasp adults to fresh plant odors were measured in a Y-tube olfactometer. Results showed that intact twigs, cones and needle were actively attractive to the weevils, but infested twigs, cones, needle and4th instar larva of weevils were negtively attractive to the weevils. The parasitoid wasps were actively attractive to seven volatiles mixture, especially4instar larva of weevils.2) Composition of volatiles released by intact and infested cones of Pinus sylvestnis var. mongolica Litv. was analyzed by GC/MS. Results showed that50volatile compounds emitted from intact cones and46volatile compounds emitted from infested cones. However,28volatile compounds of intact cones did not emit from infested ones, and24volatile compounds of infested cones did not exist in intact ones.3) The antenna and antennal sensilla of Scotts pine cone weevil Pissodes validirostris and Scambus punctatu were examined with scanning electron microscopy. The antenna of male and female adults is both flagelliform. composed of a scape, a pedicle and a flagellum. The female flagellum adult has twenty-two segments and the male has twenty-five segments. Five types of antennal sensilla were found in an antenna:trichodea. placodea. coeloconica. chaetica and Bohm bristles. Sensilla trichodea are most abundant. Sensilla trichodea(Ⅰ,Ⅱ). sensilla placodea. sensilla coeloconica and sensilla chaetica were found verticulate in flagellum, while SsⅢ are found in middle and distal end of scapes and pedicles. Bohm bristles are found at the base of scapes and pedicles. There were nosexual differences in sensillum morphology and type. There were sexual differences in sensillum number and density. The male sensillum number and density is more than the female.4) The antenna of adult cone weevil is geniculate. composed of a scape, a pedicle and a flagellum. The flagellum has seven segments. Six types of antennal sensilla were found in an antenna:trichodea. chaetica. scolopalia, palmate, basiconica and Bohm bristles. Sensilla palmate are most abundant. Sensilla scolopalia (Ss) have three subtypes:SsⅠ and SsⅡ were found verticulate in pedicle and flagellum. while SsⅢ are found in scape. Sensilla palmate, sensilla chaetica and sensilla scolopalia are found in the distal end of the seventh segment of flagella. Sensilla basiconica and Bohm bristles are found at the base of pedicles. There were no sexual differences in sensillum morphology, type and distribution.5) The electrophysiological responses of the weevil and the wasp to volatiles of Finus sylvestnis var. mongolica Litv. were analyzed by EAG. EAG does-response revealed that the weevil and the wasp were significantly attractive to seven volatiles mixture and five single synthetic compounds. Female weevil adults had a stronger response to intact to the twigs, cones, and synthetic compound tertbutylamine at each concentration. Female wasp adults had a stronger response to4instar lavar and synthetic compound1,2-dichloroethane at each concentration.6) Behavioral responses of the weevil and the parasitoid wasp adults to synthetic compounds were measured in a Y-tube olfactometer. The wasps had a strongly active response to tertbutylamine.4hydroxyl-2-d ketone and1.2-dichloroethane at0.0002μT·μL-1, but negative response to these compounds at0.02μL·μL-1. The weevils had a strongly active response to1,3,5-cycloheptatriene and isooctane at0.002μL·μL-1, but negative response to tertbutylamine.1.2-dichloroethane and isooctane at0.02μL·μL-1.