The Control And Application Technology Of Ectropis Grisescens (Lepidoptera:Geometridae) With The Entomogenous Fungi And Sex Pheromone

Ectropis grisescens Warren(Lepidoptera:Geometridae),which is widely distributed in tropical and subtropical regions of China,is one of the most severe defoliator pest insects of tea plantation.E.grisescens is inaccurately regarded as E.obliqua due to the similar morphological characteristics.The E.grisescens larvae mainly damage shoot and mesophyll,and balding of branches of tea plants,and usually caused severe economic losses.Currently,the control of E.grisescens mainly relys on insecticide,use of traditional chemical insecticide control strategy might lead to food safety and resistance problems.In addition,Eg NPV is used to controlling the E.grisescens,but propagation techniques of Eg NPV are still explored.Hence,biological control technology plays an important role in the control of insect pests.The growth of pupae was influenced with the entomogenous fungi(fungi insecticide:Beauveria bassiana and Metarhizium anisopliae),and identifying how males are attracted female adults of E.grisescens is one promising area of research since it can contribute to development of traps to monitor and control insect populations.The major research results are summarized as following:1.Effects of soil-treatment with fungal biopesticides on pupation behaviors,emergence success and fitness of E.grisescensIn the present study,we hypothesized that soil treatment with the two commercial biopesticides(Shuiguxin?)based on Metarhizium anisopliae(Metchnikoff)and Beauveria bassiana(Balsamo)could reduce the survivorship and fitness of E.grisescens.Wandering larvae of E.grisescens were allowed to pupate in soil treated with each biopesticide,and the concentrations of M.anisopliae(Shuiguxin?)and B.bassiana(Shuiguxin?)that produced the 50%mortality values(LC₅₀)were 2.9×10⁶ and 1.6×10⁷ conidia/g soil,respectively.Artificial burying the pupae using soil treated with M.anisopliae(Shuiguxin?)and B.bassiana(Shuiguxin?)(1×10⁸ or 1×10⁹ conidia/g soil for both biopesticides)also significantly reduced emergence success of E.grisescens.In addition,choice tests showed that soil treated with the high concentration of M.anisopliae(Shuiguxin?)or B.bassiana(Shuiguxin?)had repellent effects on pupating E.grisescens.However,sublethal concentrations(LC₂₅ and LC₅₀)of both biopesticides did not significantly affect fecundity,fertility and longevity of post-emerged adults.Our study showed that soil treatment with the two commercial biopesticides caused direct mortality of pupating E.grisescens,but may not effectively suppress E.grisescens populations at sublethal concentrations.The realistic application of the fungal dosage in fields should be determined in future studies.2.The evaluation of sex pheromone gland extracts and reproductive rhythms of E.grisescensAdult emergence,calling behavior,mating activities,and oviposition patterns were observed and the effect of female sex pheromone were evaluated under laboratory conditions(25±1?,L//D=14 h//10 h and 70-75%RH).Adult emergence and calling behavior occurred only at the scotophase.The peak emergence occurred 2 h into the scotophase for males and 3 h for females.Female calling behavior occurred during 1-4 d after eclosion,with most callings among the 1-day-old and the calling gradually decreasing by age.The onset of scotophase calling occurred earlier as female aged.Specifically,the onset of calling was on the 4^th h into the scotophase for 1-d-old female,2^nd h for 2-or 3-d-old female and 1^st h for 4-d-old female.Among females of 1-to 3-d-old,their callings peaked during the 6-8 h of the scotophase,reached 93.67%,83.33%(note:the peak value of 2-d-old female),and 52.00%(note:the peak value of 3-d-old female),respectively.Among the 4-d-old females,the calling peaked at the 3^rd h and only 15.67%called.Mating behavior was first observed at the 2 h into the scotophase.While the mating peak time was similar,6-8 h into the scotophase for single-pair and multiple-pair groups,the peak of oviposition was 3 d after mating.The gland extracts from the abdominal tips of 1-2 d virgin female moths were more attractive than the virgin females or the control in the wind tunnel tests.Our findings provide scientific basis to extraction and identification of E.grisescens sex pheromone.3.Observation of the ultrastructure of antenna sensilla of E.grisescensAntenna sensilla of E.grisescens was observed using scanning electron microscope(SEM)and transmission electron microscope(TEM).Three sensilla types including sensilla trichodea(ST),sensilla chaetica(SC)and sensilla styloconica(SS)was discovered and identified.Type and distribution of all identified sensilla were not difference between male and female.The physiological functions on some sensilla are to be analysed,compared with other similar insects.And ST is capable of receiving the chemical signal,and SC is to feel mechanical stimulation.However,SS has the function of taste perception.The paper provides basic data for its further study about ecology,behavior and electrophysiology of E.grisescens.4.Analysis of E.grisescens pheromone gland extracts using GC-EAD and GC×GC/TOFMSNo female-produced sex pheromones of E.grisescens had been previously identified.In the present study,female gland extracts were analyzed by coupled gas chromatography with electroantennographic detection(GC-EAD)and two-dimensional(GC×GC)gas chromatography using a time-of-flight mass spectrometric detector(TOFMS),compared the retention times(Rts)and mass spectra of gland extracts and natural compounds.Two components,(Z,Z,Z)-3,6,9-octadecatriene(Z3,Z6,Z9-18:Hy)and(Z,Z)-3,9-6,7-epoxyoctadecadiene(Z3,Z9-6,7-epo-18:Hy),were identified from pheromone gland extracts,and their electrophysiological and behavioral activity evaluated.Under laboratory conditions,Z3,Z9-6,7-epo-18:Hy elicited a stronger electrophysiological response than Z3Z6Z9-18:Hy.In the field,traps baited with Z3,Z9-6,7-epo-18:Hy alone was better than Z3Z6Z9-18:Hy.And the binary mixture of Z3,Z9-6,7-epo-18:Hy and Z3,Z6,Z9-18:Hy in a ratio of 4:1(approximate ratio of females emitting pheromone)caught more males than single component or any other blends.Our study showed that Z3,Z6,Z9-18:Hy and Z3,Z9-6,7-epo-18:Hy are the sex pheromone components of E.grisescens that they prove useful in developing alternative management tools for the pest.5.Field trapping of sex pheromone of E.grisescensEffects of pheromone dose and trap placement for the monitoring and controlling of of E.grisescens is explored with the synthetic pheromone components.And the blend of Z3,Z9-6,7-epo-18:Hy and Z3,Z6,Z9-18:Hy,in a ratio of 4:1 with the different doses,were tested for their attractiveness to males.In addition,the experiments of trap type and height were also conducted.Our results show that the optimal pheromone dose is 800?g.The bucket-funnel trap hung 40 cm below the tea canopy had the highest trapping efficiency.This study establishes optimized parameters for the pheromone trapping of E.grisescens in tea plantations.