Effects Of Different Functional Plants On Cotton Aphids And Their Predatory Natural Enemies

Planting functional plants can increase the biodiversity of farmland.Functional plants can provide food resources and habitats for natural enemies,and give full play to their pest control functions as well.Aphids are the main cotton pests in Xinjiang,which seriously influence the yield and quality of cotton.In order to evaluate the regulatory effect of functional plants on cotton aphids and predatory natural enemies in Xinjiang,this study planted functional plants to conserve natural enemies(Cnidium monnieri and Brassica napus)and repel pests(Mentha haplocalyx and Ocimum basilicumyu)at the edge of cotton fields.Through systematic investigation of the population dynamics of aphids and predatory natural enemies on functional plants and cotton,it tracked the diffusion and transfer of major predatory natural enemies between cotton and functional plants,the selective responses of cotton aphids and natural enemies to the volatiles of functional plants were measured,and the regulatory effects of functional plants on cotton aphids and predatory natural enemies were evaluated,in order to provide a reference basis for ecological regulation of planting functional plants in cotton fields to conserve natural enemies or repel pests.The main results are as follows:1.Effects of functional plants on the population dynamics of cotton aphids and their predatory natural enemiesThrough the systematic field investigation,it was found that the four functional plants could conserve the predatory natural enemies such as Hippodamia variegata,Chrysoperla sinica and Orius sauteri,the number of predatory natural enemies on the C.monnieri was the largest(821 individuals).The population numbers of H.variegata and C.sinica on cotton in the planting area of C.monnieri were significantly higher than those in the control area,and the population numbers of Aphis gossypii,Acyrthosiphom gossypii and A.atrata were significantly lower than those in the control area.The population of C.sinica on cotton in B.napus area was significantly higher than that in the control area,and the population of A.gossypii was significantly lower than that in the control area.The population numbers of H.variegata and C.sinica on cotton in M.haplocalyx area were significantly higher than those in the control area,and the population numbers of A.gossypii and A.gossypii were significantly lower than those in the control area.The population numbers of A.gossypii and A.atrata on cotton in O.basilicumyu were significantly lower than those in the control area.There was a significant negative correlation between the A.gossypii,A.gossypii and predatory natural enemies of their population.2.Transfer and diffusion of H.variegata and C.sinica between C.monnieri and cottonThrough the Rubidium element labeling technology detection,it was found that after the 3rd day of labeling,the Rubidium detection rate of H.variegata increased with the distance and showing a trend of first rising and then falling,the highest detection rate of H.variegata(100.00%)was found on cotton where was 5.5 ～ 10 m away from C.monnieri.On the 7th day after marking,the detection rate of H.variegata was the highest(100.00%)on the cotton where was 0.5 ～ 5 m away from C.monnieri.As the distance increasing,the detection rate of H.variegata was decreasing.On the 3rd day after marking,the detection rate of C.sinica Rubidium was increasing first,and then decreasing while the distance increasing.The detection rate of C.sinica was the highest(100.00%)on the cotton where was 5.5 ～ 10 m away from C.monnieri.On the 7th day after marking,the detection rate of C.sinica was the highest(93.33%)on the cotton where was 0.5 ～ 5 m away from C.monnieri.The results showed that the functional plant C.monnieri could transfer H.variegata and C.sinica to cotton for biological control of cotton pests.3.Selective behavioral responses of A.gossypii and its predatory natural enemies to different functional plantsThe selection behavior test showed that the volatiles from C.monnieri and O.basilicumyu plants could significantly attract H.variegata and C.sinica,and the volatiles from M.haplocalyx and O.basilicumyu plants could significantly repel the winged A.gossypii in the laboratory.The volatile compounds of four functional plants were extracted and identified by solid-phase microextraction and gas chromatography-mass spectrometry(GC-MS).There were 9 volatile compounds were detected,including alcohols,aldehydes,ketones,esters,phenols,terpenes,alkanes,aromatic hydrocarbons,and others.In summary,this study identified four functional plants that can conserve predatory natural enemies and repel cotton aphids through investigation.Using Rubidium marker technology to tracked the main predatory natural enemies that can be transferred from C.monnieri to cotton to biological control cotton aphids.Through selective behavior test to determined different functional plants can significantly attract predatory natural enemies or repel A.gossypii,it provides scientific basis for ecological control of planting functional plants in cotton fields to conserve natural enemies or drive away pests.