Studies On Efficacy Of Volatile Infochemicals From Tea Plants And Lavenders Regulating Behaviour Of Tea Green Leafhopper And Its Egg Parastoid Stethynium Empoascae

Tea green leafhopper Empoasca vitis(G?the) is the dominant pests in tea plantations, widespreading in China, which feed on young and tender leaves, seriously deteriorating the yield and quality of tea and affecting economic values. In order to control tea green leafhoppers, chemical pesticides are widely sprayed in tea plantations. However, the shortcoming of chemical control is known to all. Chemical controls enhance risks of health and environmental associated with remaining residues on tea leaves. And with the development of pests‘ resistance, it will lead to resurgence of primary pests and outbreaks of secondary pests. A dvocating non-toxic and environmental-friendly control, the use of color sticky plate traps with volatile infochemicals plays a major role in tea pest control. Intercro pping habitat or non-habitat plants to strengthen attraction or repellent on tea green leafhoppers and its egg parasitoid, as a result, diversity index in the tea garden will increase and establish a non-toxic and environmental-friendly control technology for this ecosystem.Studies on efficacy of volatile infochemicals from tea plants and lavenders regulating behaviour of tea green leafhopper and its egg parastoid Stethynium empoascae was the purpose. In the first, potential effect of volatiles on S. empoascae was assayed using Y-tube olfactometer and in field experiment. Secondly, the routine air entrainment was used to collect the lavenders and the resulting extract was injected into GC-MS for qualitative and quantitative analysis. Combined the repellents(push) with attractants(pull) in push-pull model used in field experiment. Analysising the community composition and phototaxis of insects and biological on tea green leafhopper and S. empoascae provide the basis for establishing a new way of prevention and treament.1. To study the behavior of S. empoascae regulated by volatile infochemicals of tea shoots, potential effect of volatiles from tea shoots on S. empoascae of tea green leafhopper was assayed using Y-tube olfactometer against the clear air as CK. The first of the results were that with the increasing weight of plant odors in a certain range, S. empoascae show significantly more times in the treated of olfactometer than clean air, but it seemed to be having the opposite effect beyond the certain range. The second was that thirteen doses of nine volatile compounds from tea shoots displayed a significant attraction on S. empoascae. In the last, screening several active components to comprise various blends at different ratio, loading blend on rubber septa to become lures, subsequently attaching lure on colour board which was used to trap S. empoascae. The results were as following:(1) the effect of six-component lure is the best, three-component lure is the next, and α-Terpinene lure showed some effects but not significant.(2)the S. empoascae were activated during 6:00 to 10:00 am, and the catches from 6:00 to 10:00 am accounted for over 60% of the total amount.(3)the half-life period of six-component lure which was added the paraffin liquid, could be delayed 17.4 hours, and the effect is more stable and smooth. All in all, volatile infochemicals of tea shoots displayed a significant attraction on S. empoascae.2. To study the behavior of tea green leafhoppers regulated by volatile infochemicals of lavenders, volatile collected by the routine air entrainment from lavenders to comprise various blends at different ratio, loading blend on rubber septa to become lures(plant odors), subsequently attaching lure on color board which was used to trap tea green le afhoppers. With the increasing weight or hours of plant odors in a certain range, tea green leafhoppers show significantly preference to CK than treatments, but it seemed to be having the opposite effect beyond the certain range. 28 volatile compounds were identified from the Lavendula pinnat shoots with fresh leaves, including 18 alkenes, 6alkanes, 1 ester, 1 aldehyde, 1 ether and 1 phenol. Alkene was the major volatile group with 53.23% of the total amount. Benzene,1-methoxy-4-methyl-2-(1-methylethyl)- was the major component with 38.41% of total content. Screening major potential components to comprise various blends at different ratio in filed trapping experiments. We identified and assessed two components Benzene,1-methoxy-4-methyl-2-(1-methylethyl)-and thymol repellent tea green leafhoppers. And the method by push-pull was used with attractant and repellent.3. To study the behavior of S. empoascae regulated by volatile infochemicals of lavenders, plant odors also used in field trapping experiments. With the increasing weight or hours of plant odors in a certain range, S. empoascae shows significantly preference to CK than treatments, and it didn‘t seem to be having the opposite effect beyond the certain range, specially.4. We tested 12 colors(jasmine yellow, bud green, earth yellow, orange, apple green, bright red, pure white, purple, lake blue, sky blue, peach red and dark green) of sticky plates in Xihu Longjing tea plantations in Meijiawu Village during the height of summer. The trapping results showed that: 1) Within the 72 hours trapping period, in total of 258182 individuals of 150 insect species belonged to 9 orders were caught, containing pest(63 species), beneficial insects(55 species) and neutral insect(32 species), with Homoptera(98.7% of total individuals) being the most dominant order group, followed by Hymenoptera(0.6%) and Diptera(0.5%). 2) The citrus spiny whitefly and tea green leafhopper were the two most dominant pest insect species, accounting for 94.2% and 2.3% of the total individuals, respectively. 3) In general, indicating the effective attraction of yellow and green sticky traps to most insects of tea plantation during the field trapping period(July 25-28, 2012). Thus, bud green sticky plates could be applied in controlling numbers of the tea green leafhoppers. The efficacy of bud green sticky plates could be significantly improved by developing more effective plant volatiles-based attractants, which is surely worthy of further study.5. In the study of insects and theirs natural enemies, the biology and behavior studies were the foundation of others. To study the biology and behavior of tea green leafhoppers and S. empoascae, the record the number and time about the S. empoascae emergence. And field investigation and indoor observation were combined during overwintering period. The S. empoascae were activated focusing on the 2 hours after dawn. The development stages of S. empoascae spend the winter in the tea green leafhoppers eggs but not in the tea plants.Above all, the behavior of tea green leafhoppers and S. empoascae regulated by volatile infochemicals of tea shoots and lavenders. Using the sticky plates with volatile cues based on Push-Pull theory model in field application of prevention of the tea green leafhoppers, or with intercropping of rosemary(pull) and Lavendula pinnat(push) could reduce the damage and have high feasibility. As the effect of visual cues(size) and volatile cues, the efficacy of color sticky plates can be significantly improved by developing more effective plant volatiles-based attractants, which is surely worthy of further study.