| Plant volatiles play an important role in the interaction between plants and insects.As a kind of specialized natural enemies of Alternanthera philoxeroides,Agasicles hygrophila mainly uses the volatile matter released by host plants through olfactory receptors to find and identify,so as to achieve the purpose of feeding.In this paper,the effects of the volatile compounds of different treatments on the biological activities,tropism,growth and reproduction of the species were studied,and the effects of the aromatic volatile compounds dibutyl phthalate and methyl salicylate on the species were determined.The main research results are as follows:(1)Volatile matter from different treatments of A.philoxeroidesIn this study,solid phase microextraction(spme)and gc-ms were used to determine the volatile matter from different treatments of A.philoxeroides.The results showed that after 1,6,12,24 and 48 h treatment,41 compounds were released,and the most volatile compounds were released after 12 h of treatment.A total of 17 kinds of volatiles released after mechanical damage were detected,and the volatiles released after 1 hour of damage were the most.A total of 28 volatile compounds were released after feeding of the first instar larvae,and the most volatile compounds were detected after feeding for 24 hours.A total of 43 volatiles were released after feeding of the second instar larvae,among which the most volatile matter was released after 48 hours of feeding treatment.Compared with other treatments,74 volatiles were released the most after the damage of the third instar larvae,among which the most volatile components were detected 24 hours after feeding.After feeding,28 compounds were released from A.philoxeroides,and the most volatile components were released after 12 h and 24 h of feeding,and 16 compounds were released,but the volatile components and content were different.After feeding,28 kinds of volatile substances were released from A.philoxeroides,among which the most detected compounds were12 h and 48 h after feeding,17 volatiles substances were found,but thecomposition and content of volatile substances were different.(2)Effects of dibutyl phthalate and methyl salicylate on the biological activity and tropism of A.hygrophilaIn this study,two specific aromatic volatiles,dibutyl phthalate and methyl salicylate,were selected to determine their effects on the activities of the 2nd instar larva and adults of A.hygrophila,and the effects of different concentrations on the tropism of male and female adults of A.hygrophila.Finally,the sublethal dose of dibutyl phthalate(LD10,LD20,and LD50)for the 2nd age larvae and adults of A.hygrophila was 0.7?mol/m L,0.9 ?mol/m L,1.2 ?mol/m L and 1.7 ?mol/m L,2.9?mol/m L,8.0 ?mol/m L,respectively.The sublethal dose of methyl salicylate(LD10,LD20,and LD50)to the 2nd larva and adult of A.hygrophila was 0.8 ?mol/m L,1.2 ?mol/m L,2.2 ?mol/m L and 2.9?mol/m L,4.1 ?mol/m L,7.9 ?mol/m L,respectively.In addition,dibutyl phthalate had a significant repellent effect on both male and female adults of A.hygrophila after being diluted 100 times,while the original drug had no significant effect after being diluted 1000 times.However,methyl salicylate had a repellent effect on female adults only when the original drug was used,and other concentrations had no significant effect.Male adults showed no significant reaction to the three concentrations.(3)Effects of dibutyl phthalate and methyl salicylate on the growth and reproduction of A.hygrophilaIn this study,the population life table of A.hygrophila was established after feeding on different concentrations of dibutyl phthalate and methyl salicylate of A.philoxeroides.Results show that compared with the control group,A.hygrophila in 0.71 ?mol/m L phthalic acid dibutyl,under the influence of development duration and significant difference,adult male and female and total insect life and spawning period and spawning were extended,but no difference.In 1.75 ?mol/m L concentration under the influence,A.hygrophila development duration and significant difference,adult male and female and spawning period and spawning has extended but no difference,but the total life expectancy and a significant difference.Compared with the control group,under the influence of 0.82 ?mol/m L methyl salicylate,the developmental durationwas shortened and the difference was significant.However,under the influence of 2.88 ?mol/m L methyl salicylate concentration,there was no significant difference in the development history of A.hygrophila,and the spawning period of total insect,female,male adult and female was shortened,but there was no difference,and the spawning amount was increased.In this paper,the effects of the specific volatiles of the host plant on the tropism and growth and reproduction of A.hygrophila were studied to explore the relationship between the selection of the host by the herbivorous insects.It is benificial for the theory and practice of host specificity determination in the field of biological control,and to elucidate the co-evolutionary relationship between insects and plants and have a good guiding significance for biological control of weeds. |
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