Effect Evaluation And Mechanism Of Methoprene And LED Lights On Control Of Lasioderma Serricorne And Ephestia Elutella

Lasioderma serricorne and Ephestia elutella are common and serious tobacco storage pests.Phosphine fumigation is usually used for prevention and control.However,phosphine has certain safety hazards to the environment and stored tobacco leaves.Studies have shown that the use of methoprene and light trapping can better control the harm of L.serricorne and E.elutella in the control of tobacco storage pests.In related studies,the control effect of methoprene on the different insect states of both pests,especially the control effect of E.elutella,is still lacking systematic research.And in the past light trap studies,more attention was paid to the attraction of different colors of light to L.serricorne,but there are few reports on the systematic research of light wavelength.This study took L.serricorne and E.elutella as the research objects,determined the control effects of methoprene and LED lights on L.serricorne and E.elutella,and analyzed the mechanism from the perspective of juvenile hormone receptor Methoprene-tolerant(Met)and opsin.The main results are as follows.1.The effect of methoprene on hatching rate was tested by the egg card impregnation method,and the effects of methoprene on pupation rate,emergence rate,developmental duration were tested by the leaf impregnation method.The results showed that the lethal effects of methoprene on L.serricorne and E.elutella increased with the increase of concentration.The egg hatching rates,larval pupation rates and adult emergence rates were significantly reduced,and the larval developmental duration was significantly prolonged.The corrected mortality rates of L.serricorne and E.elutella eggs treated with5mg/kg methoprene for 7 d were 67.2% and 50.7% respectively,the corrected mortality rates of L.serricorne larvae for 42 d was 57.1%,the corrected mortality rates of E.elutella larvae for 84 d was60.1%,the pupation rates of larvae were 9.6% and 3.6% respectively,and adults could not emerge normally.5 mg/kg is the appropriate methoprene concentration to be screened in the laboratory that can control both pests.2.RNA-seq,molecular cloning and q RT-PCR were used to analyze the juvenile hormone receptor Met genes of L.serricorne and E.elutella.The results showed that L.serricorne had two Met genes(Ls Met 1,Ls Met 2)and E.elutella had one Met gene(Ee Met).The expression of Ls Met 1,Ls Met 2 of L.serricorne and Ee Met of E.elutella continued to fluctuate in the larval stage,and the expression of Met genes was lower in the early stage of each larval stage,but up-regulated before each molting and down-regulated in the last stage before pupation.The expression of Ls Met 1,Ls Met 2 and Ee Met were up-regulated in all instar larvae treated with methoprene,which inhibited the growth and development of two kinds of larvae.3.Through laboratory and warehouse trapping tests,this study compared the phototaxis of L.serricorne to light traps with different wavelength light sources,and identified L.serricorne opsin gene sequence through RNA-seq.The results showed that L.serricorne had different phototaxis to light sources of different wavelengths,its phototaxis to 400-405 nm was the strongest,followed by 600-605 nm.The results of warehouse trapping tests showed that the amount of L.serricorne trapped by 400 nm light was significantly more than that by 380 nm light.L.serricorne had two opsins associated with sensitive light wavelength absorption,UV and LW.The phototaxis behavior of L.serricorne to 400-405 nm and 600-605 nm was in accordance with the sensitivity range of UV opsin and LW opsin respectively.L.serricorne lacked BL opsin.Therefore,400 nm wavelength light could be used to control L.serricorne in warehouses.In conclusion,methoprene and LED lights have significant control effects on L.serricorne and E.elutella.The results of this study further clarified the distribution of Met genes in different developmental stages of larvae,different body segments of adults,and the effects of methoprene on Met genes of different instar larvae.At the same time,the sequence of L.serricorne opsin gene was clarified.The results provide a basis for the application of methoprene and LED lights to the control of L.serricorne and E.elutella.