On-leaf Position Preference,population Spatial Distribution And Distributed Potential Risk Of Two Walnut Aphids

In this paper,we studied the population dynamics,leaf position separation and potential distribution areas of Panaphis juglandis Goeze and Chromaphis juglandicola Kaltenbach,This study used a combination of indoor and outdoor experiments to conduct research for two consecutive years from 2017 to 2018 in Mohe Township,Gongliu County,Yili Region.Their population distribution pattern and on-leaf position preference have also been revealed.Furthermore,the future potential global distribution of two aphid species has been emulated and predicted using CLIMEX.The results will provide fundamental information for the future control and integrated management of these two walnut pests.The main findings of the study are as follows:1.There were significant differences between the number of natural populations of P.juglandis and C.juglandicola.The population of P.juglandis is significantly higher than that of C.juglandicola.The spatial distribution of natural populations of P.juglandis has been transformed between aggregated and uniform spatial distribution with the change of population,while the natural population of C.juglandicola has a uniform spatial distribution.2.In the single-leaf space,the populations of P.juglandis and C.juglandicola firstly increased and then decreased.The population of P.juglandis can reached the maximum environmental capacity on the 21 st day,while the population of C.juglandicola continued to increase on the 21st day,but with a slowed down ration of increase.There was no significant difference in the population of mixed aphids of two species.The population of two aphids in 2017 was significantly higher than that in 2018.3.In move-free space,C.juglandicola under different treatments rapidly found the lower leaf surface at both individual and group level,and reached 100%in about 1h.On the contrary,P.juglandis took 24 h-36 h to establish a stable population in the upper leaf surface,and the ration is about 90%.The separation of the feeding positions of the two walnut aphids is universal.P.juglandis like to feed on the upper of the leaves,while C.juglandicola like to live on the lower of the leaves.4.In the fixed position of leaves,the survival individuals of P.juglandis that living on the upper leaf surface and lower leaf surface turned was significantly higher than other treatment levels.Similarly,the survival individuals of C.juglandicola living on the lower leaf surface and lower leaf surface turned was significantly higher than other treatment levels.It is indicated that the separation of feeding positions of two walnut aphids is affected by factors such as leaf structure and light intensity.5.The potential global distribution of C.juglandicola is more extensive than P.juglandis,the suitable areas of two walnut aphids covered almost all the world’s major walnut producers such as China,the United States,Turkey,Iran,Pakistan,India,Norway,and Austria.At the same time,the high and medium suitable areas of two walnut aphids in China are mainly distributed in the walnut producing provinces of Liaoning,Beijing,Hebei,Shanxi,Shaanxi,Hubei,Guizhou,Xinjiang and Yunnan.