Study On The Interrelation Between Pea Aphid And Host Plant

The aphid is a worldwide pest, mainly exist tropical, subtropical and temperate regions.They destroy crops and cause great economic losses. The aphid has a short life cycle, andfrom generation to next generation only need a few days, and spread very quickly, it willcause a seriously damage once break out. Because of the long-term use of chemicalpesticides to control aphid caused the aphid resistance to it, and the natural enemies of theaphids in the field are becoming less and less, farmland ecological system is seriouslydamaged, so it is more difficult to control aphid to damage crops. On the other hand, becauseof the use of pesticides, more and more people worried about the pesticides residues, and thepesticides residues caused the pollution of the people’s living environment. It is a big problemthat how to control aphid to damage crops effectively and make sure our environment isn’tpolluted and the ecological balance isn’t damaged at the same time. This paper is a baseresearch on the interaction between insect and it’s host plant, we use the pea aphid and broadbean as our material and want to find new ways to control the damage of aphid as soon aspossible.Through qualitative analysis of the changes of broad bean plant volatile compoundsbetween healthy plant and damaged plant, and we can know that from the result, there are15volatile compounds were detected from healthy broad bean plant and16from damaged plant.The9compounds of Octanal, Z-3-hexen-1-yl acetate, Z-3-hexen-1-ol, Benzaldehyde,Nonanal, Decanal, n-Pentadecane, Caryophyllene and Hexadecane can be detected both fromhealthy plant and damaged plant. These compounds3-Carene, E-2-hexenal,6-mthyl-5-hepten-2-one, linalool, Naphthalene and Undecanal only can be detected fromhealthy broad bean plant. But it is different from healthy plant volatiles that E-2-hexenol,trans-β-ocimene, DMNT, Methyl salicylate, Cinnamaldehyde, trans-β-farnesene and TMTTcan be detected from damaged plant.To analysis the healthy plants and damaged plants’ and free amino acids by HPLC, andthe same time analysis the free amino acids of the aphid’s body, we can know that There were20amino acids detected from phloem sap of broad bean plant, and16amino acids detectedfrom aphid haemolymph. Asparagine was the most abundant amino acid in both broad beanplant and aphid. All the8essential amino acids (EAA) were detected from broad bean phloemsap whereas all essential amino acids but methionine and tryptophan were detected fromaphid. The total EEA in broad bean phloem increased significantly with the increase of aphidfeeding. On the contrast, there was no significant difference in the total EEA in aphids onlow-degree damaged plant and seriously damaged plant. The total amino acid of seriouslydamaged plant was74.97%more than that of healthy plant, and the concentrations of all the amino acids increased significantly except Aspartic acid, Glutamic acid, AsparagineMonohydrate and Tyrosine. The TAA in aphids on seriously damaged plant was only25.57%more than that in aphids on low-degree damaged plant, likely due to significant difference inAspartic acid, Asparagine Monohydrate, Histidine and Ornithine. Furthermore, the differencesin TAA in broad bean plant (healthy plant versus aphid-infested plant) and in aphids (onlow-degree damaged plant versus on seriously damaged plant) were statistically significant.We test the EAG response of winged and wingless adult pea aphid to21plant volatilecompounds. The result showed that most of the values of EAG response of both winged aphidand wingless aphid to21compounds are less than1mV, but both of them made a strong EAGresponse to Benzaldehyde and E-2-hexenal. In addition, we found that the winged aphid had astronger EAG response to17plant volatile compounds than wingless aphid, even there aretwo times values of EAG response of winged pea aphid to Benzaldehyde and E-2-hexenalthan wingless pea aphid.The result of pea aphid indoor behavior test to the21selected compounds indicate thatthere were no attraction to them or drive them away when use single compounds or simpleequality mixture, and the same as Benzaldehyde and E-2-hexenal which the aphid made astrong EAG response. But the different result is that fresh broad bean leaves andn-Pentadecane can attract them, and the compound Octanal can drive them away, and both ofhad a significant difference(P <0.05).