Bioactivity Study On Two Species Of Scarab Beetle To Three Host Plants

Holotrichia parallela and Holotrichia oblita is widely distributed in the main agricultural area in China,is a dominant species of beetle pests.In this study clarify the relationship between feeding preference and taxis behavior of Holotrichia oblita and Holotrichia parallela adults to Chinese elm(Ulmus parvifolia),wild cotton(Abutilon theophrasti),and castor-oil plant(Ricinus communis)were measured.The main test results are as follows:(1)it was revealed for the first time,relationship between feeding preference and taxis behavior of Holotrichia oblita and Holotrichia parallela adults to Chinese elm(Ulmus parvifolia),wild cotton(Abutilon theophrasti),and castor-oil plant(Ricinus communis).Taxis behavior of H.oblita to R.communis was significantly higher than that to U.parvifolia and A.theophrasti(P<0.05).There was no significant difference in taxis behavior between U.parvifolia and A.theophrasti.However,beetles showed the highest feeding preference to U.parvifolia,among these three plants,and there was no significant difference between A.theophrasti and R.communis.Moreover,no significant difference in feeding preference was found between female and male adults of H.oblita(P>0.05).Taxis behavior of H.parallela to R.communis was significantly higher than that to U.parvifolia and A.theophrasti(P<0.05).There was no significant difference in taxis behavior between U.parvifolia and A.theophrasti.However,beetles showed the highest feeding preference to U.parvifolia,among these three plants,and there was no significant difference between A.theophrasti and R.communis.Moreover,no significant difference in feeding preference was found between female and male adults of H.oblita(P>0.05)(2)The components of the 3 plant volatiles were identified by GC-MS analysis.GC/MS analysis showed that plant volatile compounds in the three plants were largely different Comparison of 3 kinds of plant essential components of volatiles of the similarities and differences,in which there are 13 compounds for 3 kinds of plant volatiles in the composition,for example: dibutyl phthalate,(Z)-3-hexenyl isobutyrate,3-hexanol,nonanal,pinene,,cis-3-hexenol,(Z)-3-Hexen-1-ol,ester etc..But at least 23 or more components are different.In 3 kinds of plant volatiles in the main components and their proportions are not the same,for example: component of Chinese elm(Ulmus parvifolia)are alkenes(33.3%),esters(23.1%),alcohol(17.9%)and alkanes(10.3%);the top 4 is castorcastor-oil plant(Ricinus communis)(alkane 27.8%),esters(25%),alcohol(16.7%)and alkenes(11.1%);the compunds of wild cotton(Abutilon theophrasti)is mainly esters,alcohols and alkanes(22.5% each),aldehydes and alkenes tied for fourth place(15%).(3)In the Y-olfactometer tests,(Z)-3-hexenyl isobutyrate,Dibutyl phthalate,(Z)-3-hexenyl Acetate,Linalool,Phenol,Methyl salicylate,β-caryophellen at the concentration of 10 μg/μL was found to be more attractive to H.oblita in comparison with control(hexane),while 3-Carene,(E)-2-Nonenal and α-phellandrene were less attractive than hexane.(P<0.05 or P<0.01).(4)The experimental results of EAG reaction of 24 plant volatiles of standard samples to Holotrichia parallela showed that the(Z)-3-hexenyl Acetate,Linalool,Phenol,Methyl salicylate,β-caryophellen have high value at the same concentration than control,and there is a significant difference(P<0.05).At different concentrations,the EAG value of standard compounds are also different.