Selection of High-efficient Safe Pesticides for Controlling Tea Lesser Leafhopper(Empoasca vitis)

[Objective] This study was conducted to select a batch of new high-effi- cient low-toxicity high-selectivity pesticides for the application in tea gardens. [Method] This experiment was designed with 12 treatments including clear water as the CK, in randomized block arrangement, with 4 replications, and each plot had an area of 30 m2. The pesticides were sprayed in the high occurrence period of larvae of tea lesser leafhopper when tea shoots grew vigorously. [Result] In the 11 pesti- cides, 100 g/L bifenthrin EC , 70% imidacloprid WDG and 150 g/L indoxacarb EC were the best pesticides with efficacies above 90%; and in the bio-pesticides, 0.5% azadirachtin SC showed an efficacy over 87.97%. [Conclusions] Among the tested pesticides, 100 g/L bifenthrin EC , 70% imidacloprid WDG and 150 g/L indoxacarb EC could effectively control tea lesser leafhopper during the outbreak of tea lesser leafhopper, and when the occurrence degree of tea lesser leafhopper is below the medium level, environment-friendly 0.5% azadirachtin SC, 0.5% veratrine SC, 0.3% matrine SC and 4.0×10^10 spores/g Beauveria bassiana OD could be selected.

Exploiting push-pull strategy to combat the tea green leafhopper based on volatiles of Lavandula angustifolia and Flemingia macrophylla

Thirteen volatile compounds were identified from Flemingia macrophylla plants. Eight major components significantly attracted the tea green leafhoppers, Empoasca flavescens F. Based on their relative abundances, following synthetic blends were made for field experiments: 1) eight-component-attractant blend included Z-3-hexen-1-ol, Z-3-hexenyl acetate, Z-ocimene, Me SA, Z-3-hexenyl butyrate, dodecane, hexadecane and nonanal at 10, 10, 1, 11, 2, 6, 2 and 4 mg mL^-1 in n-hexane, respectively;2) four-component-attractant blend #1 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and nonanal at 2, 10, 10 and 4 mg mL^-1 in n-hexane, respectively;3) four-component-attractant blend #2 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and Me SA at 2, 10, 10 and 11 mg mL^-1 in n-hexane, respectively. Thymol and 1-methoxy-4-methyl-2-(1-methylethyl)-benzene, identified from Lavandula angustifolia aeration samples, significantly repelled the leafhopper as strong repellents when tested alone or in combination at 10 mg mL^-1. For field bioassays, each attractant lure was attached to a bud green sticky board hung from a bamboo stick at above tea plant level for catching the leafhoppers, whereas the repellent dispenser was tied to a tea branch inside tea clump for pushing the leafhoppers away from tea clumps. The results showed that the eight-component-attractant blend caught similar numbers of the leafhopper as did the four-component-attractant blend #1 at about 53–79 leafhoppers/trap/day, which were significantly higher than those on the hexane-control bud green sticky boards. Average leafhopper catches from un-baited sticky boards were about 51–73 leafhoppers/trap/day when pushed by the repellents placed inside tea plants, with the two-component-repellent blend being more effective than their single components. When the two-component-repellent blend was further tested with the three attractant blends in a push-pull fashion, average trap catches ranged from 62 to 92 leafhoppers/trap/day. Control efficacy on the leafhoppers within the push-pull zones increased progressively from day 1(43%) to day 5(73%). This push-pull approach might have a great potential as a green control strategy for combating the tea green leafhoppers.

Genomic Variations in the Tea Leafhopper Reveal the Basis of Its Adaptive Evolution

Tea green leafhopper(TGL),Empoasca onukii,is of biological and economic interest.Despite numerous studies,the mechanisms underlying its adaptation and evolution remain enigmatic.Here,we use previously untapped genome and population genetics approaches to examine how the pest adapted to different environmental variables and thus has expanded geographically.We complete a chromosome-level assembly and annotation of the E.onukii genome,showing notable expansions of gene families associated with adaptation to chemoreception and detoxification.Genomic signals indicating balancing selection highlight metabolic pathways involved in adaptation to a wide range of tea varieties grown across ecologically diverse regions.Patterns of genetic variations among 54 E.onukii samples unveil the population structure and evolutionary history across different tea-growing regions in China.Our results demonstrate that the genomic changes in key pathways,including those linked to metabolism,circadian rhythms,and immune system functions,may underlie the successful spread and adaptation of E.onukii.This work highlights the genetic and molecular basis underlying the evolutionary success of a species with broad economic impacts,and provides insights into insect adaptation to host plants,which will ultimately facilitate more sustainable pest management.

Field Efficacy Trial of Trapping Tea Green Leafhopper with Pheromone Insect-attracting Board

[Objective]The paper was to study the control effect of pheromone insect-attracting board on tea green leafhopper（Empoasca vitis Gothe）in fields. [Method]Pheromone insect-attracting board and ordinary insect-attracting board were used to trap tea green leafhopper in fields,and control efficacies were studied.[Result]The daily trapping effect of pheromone insect-attracting board on tea green leafhopper was 19.0 insect/grid,while that of ordinary insect-attracting board was 13.8 insect/grid.The highest control effect of pheromone insect-attracting board and ordinary insect-attracting board were 71.6% and 63. 6%,respectively.The distribution of tea green leafhopper in two types of boards showed the following regularities：more in upper edge and less in lower edge of boards,more on both sides and less in the middle of boards.The mean values of control effects of two insect-attracting boards were significantly different（t =5.66

Behavioral responses for evaluating the attractiveness of specific tea shoot volatiles to the tea green leafhopper, Empoaca vitis

The tea green leafhopper, Empoasca vitis Gothe, is one of the most serious insect pests of tea plantations in China's Mainland. Over the past decades, this pest has been controlled mainly by spraying pesticides. Insecticide applications not only have become less effective in controlling damage, but even more seriously, have caused high levels of toxic residues in teas, which ultimately threatens human health. Therefore, we should seek a safer biological control approach. In the present study, key components of tea shoot volatiles were identified and behaviorally tested as potential leafhopper attractants. The following 13 volatile compounds were identified from aeration samples of tea shoots using gas chromatography-mass spectrometry （GC-MS）： （E）-2-hexenal, （Z）-3-hexen-1- ol, （Z）-3-hexenyl acetate, 2-ethyl-1-hexanol, （E）-ocimene, linalool, nonanol, （Z）-butanoic acid, 3-hexenyl ester, decanal, tetradecane, β-caryophyllene, geraniol and hexadecane. In Y-tube olfactometer tests, the following individual compounds were identified： （E）-2- hexenal, （E）-ocimene, （Z）-3-hexenyl acetate and linalool, as well as two synthetic mixtures （called blend 1 and blend 2） elicited significant taxis, with blend 2 being the most attractive. Blend 1 included linalool, （Z）-3-hexen-l-ol and （E）-2-hexenal at a 1： 1：1 ratio, whereas blend 2 was a mixture of eight compounds at the same loading ratio： （E）-2-hexenal, （Z）- 3-hexen-l-ol, （Z）-3-hexenyl acetate, 2-penten-l-ol, （E）-2-pentenal, pentanol, hexanol and 1-penten-3-ol. In tea fields, the bud-green sticky board traps baited with blend 2, （E）-2- hexenal or hexane captured adults and nymphs of the leafhoppers, with blend 2 being the most attractive, foUowed by （E）-2-hexenal and hexane. Placing sticky traps baited with blend 2 or （E）-2-hexenal in the tea fields significantly reduced leathopper populations. Our results indicate that the bud-green sticky traps baited with tea shoot volatiles can provide a new tool for monitoring and managing the tea leafhopper.