Study On Oviposition Behavior And Factors Affecting Oviposition Of The Asian Citrus Psyllid,Diaphorina Citri Kuwayama(Hemiptera:Psyllidae)

The Asian citrus psyllid,Diaphorina citri Kuwayama(Hemiptera: psyllidae)is the vector of Candidatus Liberibacter asiaticus or Candidatus Liberibacter americanus,which also is one of the important insect pests that damage Citrus Industry.The behavior of insect oviposition is an important behavior in insect life cycle and has important biological significance for its survival and reproduction.The activity of insect newly-hatched larvae are almost weak,and their survival also almost depend on the selection of insect female adult to species of host-plants and the specific oviposition sites on the host plants.Combined with field investigations and laboratory experiments,the oviposition behavior of D.citri on citrus plants were studied,and the factors affecting oviposition of D.citri were also conducted in this paper.The structure of the external genitalia of D.citri adults and their sensilla on the external genitalia were studied using stereomicroscope and environmental scanning electron microscopes(SEM),the influence of host plant volatiles and light waves on host selection of D.citri were also studied in order to explore the oviposition rules and oviposition selection mechanism of D.citri,which could provide new ideas and approaches for the prevention and control of this insect pest.The main results are the following:1.Study on oviposition behavior of the D.citri : When female adult of D.citri prepared for oviposition,it was static on the host while its pair of antennae were quivering.If the antennae stopped quivering,the female would prepare for laying eggs or removing to other sites to continue the above behavior until it found a suitable site to lay eggs.When the female began to oviposite,the gap between the anal segment and subgenital plate was enlarged,and the ovipositor inserted into the host buds.After oviposition,female withdrew the ovipositor rapidly and the gap of anal segment and subgenital plate closed slowly during this withdrawing process.D.citri female adult trends to laying its eggs into the tender buds of host.For Citrus reticulate cv.Shatangju,D.citri female inclined to laying eggs on the folded or semi-folded tender buds(<10.00 mm in length),with maximum of egg 58 in one bud.2.observation on External genitalia and its sensillum of D.citri:External genitalia of D.citri female adult was composed of anal segment,a pair of dorsal lateral lobes,subgenital plate,a pair of octavalvae,a pair of dorsal valvula,abdominal valve stents,ventral lobe stent,ventral lobe basal process and procidentia.External genitalia of D.citrimale adult was composed of anal segment,subgenital plate,penes and a pair of harpago.The sensillum of external genitalia of D.citri was observed by SEM,sensillum trichodea and Chaetica sensilla were found on the external genitalia of both D.citri female and male adults.Compared with the male,female had the sensory papilla and more subtypes of Chaetica sensilla.The function of sensillum of female genitalia could help mating and arranging the eggs in the process of ovipositon.3.Determination on the taxis responses of D.citri to volatile compounds of hosts:The volatile compounds of various buds or new leaves from Murraya exotica L.and Citrus reticulate cv.Shatangju were extracted by headspace solid phase micro-extraction method,and analyzed by gas chromatography/mass spectrometry(GC/MS).Four kinds of the common volatiles were beta-cariofillene,A-humulene,Hexanal and 2-(E)-hexenal.Taxis responses of D.citri adults to these four common volatiles were tested by four-armed olfactometer.The results showed that D.citri adults were attracted strongly to 1μL/mL A-humulene,10μL/mL beta-cariofillene and 100μL/mL 2-(E)-hexenal respectively.4.Determination on the taxis responses of D.citri to to various wavelength lights:The taxis responses of D.citri to six LED lights including purple(395-400 nm)、green(520-530 nm)、bule(465-680 nm)、orange(600-610 nm)、yellow(590-595 nm)、red(620-630 nm)were studied.The results showed that D.citri adults were attracted strongly to these six LED lights in dark condition.In the condition of white light,D.citri adults were attracted strongly to green and purple lights,while escaped from the bule,orange,red and yellow lights.In contrast to the green light,D.citri adult was attracted significantly to purple light.