The Role Of Volatile Organic Compounds And Nutrients From Tomato And Eggplant On Host Selection Behavior Of Greenhouse Whitefly (Trialeurodes Vaporariorum Westwood) (Hemiptera:Aleyrodidae)

Greenhouse whitefly,Trialeurodes vaporariorum(Westwood)(Hemiptera: Aleyrodidae)is the most detrimental pests in the agricultural crops worldwide and cause substantial annual crop losses,either by their direct feeding behavior or ability of transmitting plant viruses.The behaviour of T.vaporariorum is known to be affected by plant volatile cues,while their performance alters with the nutritional qualities of the host plants.However,its attraction to specific volatile cues has not been deeply studied yet.Similarly,the relationship of plant nutrients and volatile organic compounds(VOCs)for host accepting and settling behavior of T.vaporariorum has so far not been proven.First,we attempted to determine the most attractive plant cultivars for T.vaporariorum among the most commonly grown four intact(uninfested)eggplant and three intact tomato cultivars.Further,we observed the aggregation behaviour of whiteflies on conspecifics-infested plants and then,assessed the relationship of plant nutrition enrichment and VOCs on the host preference behavior of whiteflies.Last,we analysed the chemical compounds from the most whitefly attractive intact plants and infested plants to identification of the attractive volatile compounds.Behavioural assay experiments were performed in Y-tube olfactometer,wind tunnel,net cages and also greenhouse.Then,headspace volatiles were determined by Solid-phase Micro Extraction(SPME)and gas chromatography-mass spectrometry(GC-MS).Electrical penetration graph(EPG)technique was used to observe the feeding preference of T.vaporariorum.As nutrients,nitrogen,sugar(fructose,glucose and sucrose)and amino acids were measured on leaves of the plants.Finally,capabilities of whitefly attraction to identified synthetic volatile compounds were measured in Y-tube,net cages and wind tunnel.Our results demonstrated that whiteflies had the highest preference for the intact eggplant Kuai Yuan Qie(KYQ)and also have better performance on KYQ.Although,whiteflies settled on less attractive plants in no-choice condition,they were then gradually attracted to the most preference plant cultivar when they were subsequently offered the highest preference.Infested KYQ has a significant ability for attracting both male and female whiteflies while the most attractive tomato cultivar YG repels conspecific females.The amounts of nitrogen,total amino acids,essential amino acids and sugars were higher in the highest whitefly attractive eggplant KYQ and tomato YG.Long duration of phloem sap feeding on KYQ indicates the host acceptance of T.vaporariorum.The high quantities of green leaf volatiles(GLVs),terpenoids and total volatiles on KYQ and YG indicating the relationship of plant volatiles and nutrients on whitefly host preference.Even damage occurred by the same herbivore species,emitted volatiles and conspecifics attractions were changed by the plant cultivars.The volatile emissions among different plant cultivars in individual species and infested versus intact plants were profoundly different.Among those volatiles,the green leaf volatile(GLV)((Z)-3-hexen-1-ol)and major terpenoids(?-pinene,(E)-?-caryophyllene,?-humulene)had a main role for changing whitefly behaviour whereas we further identified ?-pinene,(E)-?-caryophyllene and also Z-3-hexen-1-ol as attractive chemicals and ?-farnesene and ?-phellendrene as repellents for T.vaporariorum.In conclusion,the eggplant KYQ seems to be the nutritionally superior and VOCs rich host for T.vaporariorum and provides a basis for developing sustainable trap cropping system for manipulate T.vaporariorum.Plant contains nitrogen,essential amino acids and sucrose has capability to enhance host acceptance behavior of whiteflies.Plant volatiles together with nutrients play pivotal role for whitefly attracting from distance and keep them on a host without moving to other plants.Collectively,these studies indicate the importance of terpenoids and GLVs in the T.vaporariorum host-location process.However,the volatile blends responsible for attracting large quantity of whiteflies in odor-mixed natural conditions are still difficult to determine.Hence,future research should be carried out in the fields to assess the potential trapping effectiveness of the chemicals.Moreover,examine the electrophysiological responses of whiteflies' antennae to individual chemical compounds and also mixtures of synthetic blends are also worth to determine their exact preference.