| Sesamia inferens Walker(Lepidoptera:Noctuidae)is one of the main pests on the rice.It has a wide host range and is a typical polyphagous insect.This pest was usually thought to be secondary pest in rice,and general appear at marginal part of rice fields and injured less serious than Chilo suppressalis and Tryporyza incertulas.Thus,people have not paid much attention on its prevention and research.Since 1970s,with the innovations in farming and diversification of farm products,the lost caused by this pest became serious.Recently,Sesamia infernes even becomes the superior species of rice borers in some areas.So,it attracts attention of the researchers nowadays.In this work,the biological habits of Sesamia inferens concerning with its control were studied,including host preference and fitness,insecticide resistance variation among different geographic populations,and sensitivity to light of different wave length.A method was proposed to enhance the selectivity of light trap,and the base line data for 7 insecticides were obtained for monitoring insecticide resistance of Sesamia inferens with diet surface overlay bioassay.The results were summarized as follows:1.Oviposition preference and larva development of Sesamia inferens on various host plantsThe oviposition preference and larva development of S.inferens on different host plants were studied under laboratory conditions.The test with the combination of four crops with nature growing plants in equal pots or area showed that the accumulated borer's eggs laid on rice,corn,wheat,water bamboo and cole were 58.7%,24%,11.2%,6.1%and 0%of the total,respectively,and with the four-crop combination,it was 39.8%on wheat,56.4%on corn,39.8%on water bamboo and 0%on cole.When the plants were cut for the consistent height,the egg proportions were 81.4%on rice,16.8%on corn,1.8%on water bamboo and 0%on cole in this four-crop combination.In the tow species combinations of rice with different weeds,barnyard grass,vetiver and eleusine indica sheared 31%,24%and 9%,of the total eggs,respectively.When neonates were inoculated and fed for 30 days,the surviving rate was found after feeding them 30 days indoor,we observed that the water bamboo,rice,corn and wheat ultimate survival rate was 68.2%on water bamboo,50.1%on rice,47.7%on corn and 20.7%on wheat,and pupae were found only on water bamboo.Comparison analysis revealed that rice was always the preferred ovipositing plant for S.inferens in the limited space,and S.inferens larvae developed fastest on water bamboo.Barnyard grass and vetiver has a certain influence on oviposition preference.2.Insecticide resistance monitoring of Sesamia inferens collected from three geographical areas in China and related baseline dataMonitoring the resistance level for frequently-used insecticides in the pink stem borer S.inferens collected from different geographical areas was conducted,the growing trend and regional level disparity of the resistance level were analyzed and the related baseline data verified.Thus,necessary knowledge for better resistance monitoring and rational insecticide application could be provided.The old larvae of S.inferens were collected from three different geographic populations and bred separately for a generation indoor.The diet surface overlay bioassay with the neonates was conducted for the test.No obvious difference in the resistance to different insecticides was found among the S.inferens populations collected from GuiXi?WenLing and NanJing in 2014,with LC50 value(mg/L)ranged 0.0650?0.2094 for Abamectin,0.2626?0.5692 for Chlorantraniliprole,0.4788?1.2417 for Flubendiamide,3.4874?6.1524 for Phenthoate,3.6204?5.6529 for Indoxacarb,and 64.8287?89.6437 for Chlorpyrifos,except for Spinosad which ranged 0.1065?0.6846 and showed about 6 times of difference.When the monitoring data were compared in time course,it was found that Abamectin,Chlorantraniliprole,Indoxacarb and Chlorpyrifos did not change their toxicity to this pest during the recent 5 years,with the LC50 fluctuations within 2 times.However,the S.inferens was found develped resistance to Phenthoate.As compared with the data monitored in 2009 and 2010,WingLing population in 2014 had increased 12.79 and 10.29 fold resistance,respectively,and NanJing population in 2014 also increased by 9.53 and 8.72 times,respectively.When all the insecticide toxicity data for S.inferens monitored by the diet surface overlay bioassay were analyzed,the results showed that the relative baseline data tested with laboratory recovery strain and reported by Zhang et al.in 2012 is similar to the most susceptible field populations monitored,with only 1.7 times amplitude of fluctuation.In conclusion,the pink stem borer collected from three geographical areas in China had developed low to middle level of resistance to Phenthoate.In partial area,the sensitivity of this pest to Spinosad was found decreased too.Whereas,no significant resistance to the other insecticides tested was found.The baseline data reported by Zhang et al.in 2012 can be used as the relative susceptible baseline data for monitoring the field population resistance of S.inferens with the method of the diet surface overlay bioassay.3.Phototaxis and influencing factors of Sesamia inferens(Walker)under LED lights of different wavelengthIn this study,the new light source,monochromatic LED lights,was introduced for experiments to find a way to trap S.inferens selectively.After checking ten monochromatic LED lights with the wave-length ranged from 365 nm to 625 nm,it was found that this pest was attracted strongly by 460?465 nm wavelength light delivered by the monochromatic LED.In the trap test with adults of different age,the highest trap rate was found with the adults of 3-days old.When male and female were compared,it was found that all the lights with different wavelength were much more efficient for the males.This result could be used to develop a kind of selective light trip for S.inferens,which might lead to real pest light trips by overcoming the disadvantage of traditional light trip,broad spectrum attracting,and minimize the harm to natural enemies.This kind of light trip should play an important role in monitoring and controlling S.inferens in field. |
PDF Full Text Request