The Semiochemicals In Host Location Of Longhorn Beetle Batocera Horsfieldi (Hope)

The longhorned beetle,Batocera horsfieldi(Hope)(Coleoptera:Cerambycidae),is one of most abundant and destructive cerambycids widely distributed in China.The larvae cryptic feeding habit makes the control of such wood-boring pests difficult.So to be effective,control strategies have to be based on controlling or killing longhorned beetle adults that are exposed to wild to feed and copulate.Our studies researched the behavioral and electrophysiological responses of B.horsfieldi adults to feeding- or larval-host plant odors present in headspace collections.In order to identify the range of feeding- or larval-host-associated volatiles that the longhomed beetles can detect,therefore,maybe develop attractants or reples for adults that could be used in a push-push control program. And we also researched the morphology,ultrastructure and distribution of sensilla on the antennae,mandible palp and labial palp of B.horsfieldi adults by scanning electron microscopy,to realize more about the olfaction recept mechanism in this species.The main results as follows:1.Olfactometer Bioassays to host plant volatilesWhen compared with the control air,both virgin sexes were significantly attracted to odors from Rosa multiflora Thunb.volatiles in olfactometer bioassays,mated females were attracted to volatiles from the two host plants.But all of the beetles tested showed no significant different responding between R.multiflora and Populus sp.2.The identified compounds of host plant volatiles10 and 16 compounds were identified from R.multiflora and P.sp.by TCT-GC/MS respectively,and 5 compounds common to both two host plant species included:hexanal, E-2-hexenal,Z-3-hexen-1-ol,1R-α-Pinene andβ-Pinene,but the relative proportion were different for each species.The mostly compounds of R.multiflora Thunb.are Limonene, 3-carene andβ-Pinene.E-2-Hexenal is the most abundant component of the floral scent of P.sp.,hexanal,Z-3-Hexen-1-ol and E-2-Hexen-1-ol acetate in the next place.3.EAG activity of synthetic compoundsAll of the identified compounds were tested for EAG responses of the B.horsfieldi antennae.According to the electrophysiological assessment of 100μg/μl compounds,we selected eight higher EAG-active components for EAG dose-response:Z-3-Hexen-1-ol, 3-pentanol,Z-2-Penten-1-ol,3-carene,Hexanal,E-2-Hexen-1-al,E-2-Hexen-1-ol and 1-penten-3-ol.Most of EAG responses of B.horsfieldi increased with stimulus strength. The EAG responses of Z-3-Hexen-1-ol,Z-2-Penten-1-ol,Hexanal,E-2-Hexen-1-ol and 1-penten-3-ol at the higher dose were significantly differences among mated female, virgin female and male.4.Bioassay for behavioral activity of EAG-active compoundsWhen compared with the liquid paraffin(blank control),males showed a significantly preference for the Z-3-Hexen-1-ol at a dose of 1 and 0.1μg/μl and E-2-Hexen-1-ol at a dose of 1μg/μl,females showed a significantly preference to Z-3-Hexen-1-ol at a dose of 1μg/μl and to 3-Pentanol at a dose of 0.1μg/μl.Both of males and females showed a significantly preference for blank control over the 3-Carene and 1-penten-3-ol at a dose of 100μg/μl,and males showed a preference for blank control over the E-2-Hexen-1-al at a dose of 1μg/μl.5.Observation of sensilla on the cephalic appendage of B.horsfieldi with SEMThe antennae,mandible palp and labial palp of B.horsfieldi adults were observed by scanning electron microscopy.The antennae contained five types sensilla,including sensilla trichodea,s.basiconica(including five subtypes:BⅠ～BⅤ),s.cheatica (including two subtypes:CHⅠand CHⅡ),s.grooved peg,s.cavitata-peg,respectively. Sexual dimorphism was found in B.horsfieldi,the length of the antennae of male were significantly longer than that of females;s.grooved peg was only found on the female antenna,and female antenna contained more s.BⅠ,s.BⅡand s.ChⅡthan males,while the number of s.BⅢwas fewer than that of males;the average length of s.cheatica of female was significantly longer than that of males.Both mandible palp and labial palp contained five types of sensilla,including s.trichodea,s.ChⅡ,s.twig basiconca,s. campullacea and s.aperture.Mandible palp contained more s.twig basiconca and fewer s. campullacea than labial palp.The number of s.twig basiconca was higher in female antennae,and s.campullacea was higher in male.