Herbivore-induced And Nitrogen-treated Volatiles Released From Solanaceous Plants Affect Host Selection Behavior Of Bemisia Tabaci(Hemiptera:Aleyrodidae)

The sweetpotato whitefly,Bemisia tabaci(Gennadius)(Hemiptera:Aleyrodidae)Middle East-Asia Minor 1(MEAM1),previously recognized as Bemisia tabaci biotype B,is a worldwide important insect pest of horticultural,agronomic and ornamental crops.This insect pest has over six hundred host plant species globally.Volatile blends released from plants play an important role to select the suitable host plants of herbivores.Prior to this study,a little is known about the role of volatile blends released from different solanaceous plants including eggplant,tomato and sweet pepper to host selection behavior of phytophagous insects.It is also less studied about the effects of VOCs released from herbivore-damaged plants on the herbivores themselves for their host plant selection procedure.Furthermore,nitrogen concentrations of the plants affect the emission of volatile organic compounds(VOCs)that could further influence on the infestation behavior of herbivores have been poorly studied.In this study,we assayed the responses of B.tabaci to three solanaceous plants,eggplant,tomato and sweet pepper using a wind tunnel and a Y-tube olfactometer.We also investigated the infestation behavior of B.tabaci to tomato plants after single and multiple herbivory of B.tabaci and the green peach aphid,Myzus persicae with a free choice and an olfactometer experiments.Moreover,we determined the responses of B.tabaci to tomato plants that produced different levels of VOCs after application of different levels of nitrogen with a wind tunnel and an olfactometer.Subsequently,we analyzed and quantified the VOCs emanated from intact three solanaceous plants(eggplant,tomato and sweet pepper),healthy and herbivore(s)damaged tomato plants and different levels of nitrogen treated tomato plants using gas chromatography-mass spectrometry(GC-MS)to observe the role of VOCs on the host plants choice of B.tabaci.Our results revealed that the highly attractive eggplant released a leading amount of cyclohexane,2-ethenyl-1,1-dimethyl-3-methylene-;2-hexanone oxime;3-hexen-l-ol,acetate;(E)-?-ocimene;(E/Z)-2-methylbutyl aldoxime and terpinen-4-ol;the moderately attractive tomato emitted a great amount of P-phellandrene;4-carene;a-pinene;(E)-?-ocimene;nerolidol,(Z)-and myrcene whereas the least preferred sweet pepper emanated a huge amount of nerolidol,(Z)-;linalool;cyclohexane,2-ethenyl-1,1-dimethyl-3-methylene-,?-cadinene;and ?-elemene.Our results also demonstrated that significantly less preferred single and multiple herbivory damaged tomato plants were emitted higher quantity of five volatile compounds,?-pinene,?-phellandrene,?-phellandrene,(E,E)-farnesol and isoshyobunone than undamaged tomato plant.a-pinene,?-phellandrene,(E,E)-farnesol and their different mixtures were repelled B.tabaci in a free-choice experiment.However,our results indicated that high levels of nitrogen treated tomato plants were significantly preferred by B.tabaci females because of the significantly reduction of eight volatile compounds,?-pinene,(+)-4-carene,?-terpinene,?-cymene,?-phellandrene,?-copaene,?-caryophyllene and?-humulene production than normal and below normal levels of nitrogen treated tomato plants.The differences in volatile blends,components and contents among the three solanaceous plants,healthy and herbivore damaged plants and different levels of nitrogen treated plants could provide information about the suitability of host plant to B.tabaci.