Microvitellogenin(mVg)belongs to the lepidopteran-specific lipoprotein_11 super family and is thought to be involved in insect reproduction.However,the function of mVg in reproduction has not been established.In this ...Microvitellogenin(mVg)belongs to the lepidopteran-specific lipoprotein_11 super family and is thought to be involved in insect reproduction.However,the function of mVg in reproduction has not been established.In this study,we identified and characterized MsmVg in Mythimna separata,a destructive insect pest of grain crops.MsmVg is comprised of a 1,310 bp open reading frame(ORF)encoding 437 amino acids.Structural analysis showed that MsmVg contains three conserved domains in the lipoprotein_11 super family,including the all-α-N-terminal domain(NTD),a Pseudomonas putida homologous domain(PPD),and an all-β-C-terminal domain(CTD).MsmVg was highly expressed in mature female adults and enriched in the ovaries of 3-day-old female adults.Disruption of MsmVg by RNA interference did not change the expression of MsmVg,vitellogenin(MsVg)or the vitellogenin receptor(MsVgR)in fat bodies,but it inhibited their transcription in ovaries.Phenotype analysis showed that knockdown of MsmVg did not affect yolk deposition in ovaries,but impaired eggshell formation and led to a reduction in the reproductive capacity.Furthermore,knockdown of MsmVg significantly inhibited the expression of genes associated with eggshell formation(MsChP1-3 and MsFcP3C).Taken together,these data suggest that MsmVg plays an important role in female reproduction by affecting eggshell formation in M.separata,which provides a potential target for managing this insect pest.展开更多
In insects,the number and specificity of antennal lobe glomeruli often reflect the number and diversity of expressed chemosensory genes,which are linked to its ecological niche and specific olfactory needs.The orienta...In insects,the number and specificity of antennal lobe glomeruli often reflect the number and diversity of expressed chemosensory genes,which are linked to its ecological niche and specific olfactory needs.The oriental armyworm,Mythimna separata,is an important and common lepidopteran pest of cereal crops.Given its reliance on the olfactory system for crucial behaviors,understanding the evolutionary potential of this system requires a thorough characterization of the anatomical structure of the primary olfactory center.Here,we systematically identified all antennal lobe glomeruli of M.separata based on synaptic antibody immunostaining and mass staining of the olfactory sensory neurons.A total of 69 glomeruli were identified in females and 65 in males,and an intuitive nomenclature based on glomerular positions was applied.Our findings uncovered some sex-specific glomeruli in this species.There were ten female-specific glomeruli and three male-specific glomeruli,except for the macroglomerular complex(MGC)units,with a notable observation that the female labial pit organ glomerulus was larger than its male counterpart.Additionally,we identified four antennal-lobe tracts(ALTs)and retrograde labeling from the calyx revealed that all glomeruli were innervated by the medial ALT projection neurons.The comparison of the olfactory system structures between M.separata and sympatric moths supports their evolutionary convergence in noctuid moths.These results collectively lay the foundation for future studies on olfactory processing in M.separata.展开更多
The changes of climate factors and the number of Mythimna separata in Menghai County during 1982 -2007 were analyzed, and the relationship between them was discussed. The results showed that there was certain relation...The changes of climate factors and the number of Mythimna separata in Menghai County during 1982 -2007 were analyzed, and the relationship between them was discussed. The results showed that there was certain relationship between the outbreak of M. separata and the climate conditions. There was extremely significant correlation between temperature and the number of M. separata. The temperature affected the occurfence amount of M. separata and the regression equation was y=2.691 x-57.123（ P^2 =0.110）. There was no significant correlation between the relative humidity and the amount of M. separata. But the rainfall had significant relationship with the large occurrence of M. separata.展开更多
Migratory insect pests tend to suddenly immigrate into new habitats over a short period to simultaneously lay eggs in clusters,resulting in gregarious larvae that cause severe damage to crops.These aggregated larvae c...Migratory insect pests tend to suddenly immigrate into new habitats over a short period to simultaneously lay eggs in clusters,resulting in gregarious larvae that cause severe damage to crops.These aggregated larvae can adapt well to various natural enemies and pathogens in their new habitats,but how their resistance might be enhanced and its immunological significance remain unknown.Here,we examined how infection by a pathogen and a parasitic fly affect the immune response and migratory behavior in two phases of the oriental armyworm,Mythimna separata,which differ dramatically in their flight capacity and fecundity.The gregarious larvae displayed greater resistance than solitary larvae to the challenges of both the entomopathogenic fungus Metarhizium anisopliae and the parasitoid Exorista civilis.In response to a challenge by M.anisopliae,gregarious larvae exhibited more pronounced increases in phenoloxidase(PO)activity and lysozyme activity than solitary larvae.Furthermore,in addition to the greater PO and lysozyme activities,the levels of dopamine and 5-hydroxytryptamine(5-HT)were also greater in challenged gregarious and solitary larvae.Injection of dopamine(or 5-HT)significantly enhanced PO activity,lysozyme activity,antibacterial activity and larval survival.Subsequently,there was a significant increase in the flight capacity of adults derived from gregarious larvae challenged by M.anisopliae;while no significant variation was observed in the adults from challenged solitary larvae.The preoviposition period,oviposition period and fecundity were not significantly affected by M.anisopliae,regardless of whether the larvae were gregarious or solitary.These results provide new insights into the relationship between migration and immunity in insects,and their behavior after immunization.展开更多
Resistance of five field populations of Mythimna separata（Walker） collected from Shaanxi and Shanxi provinces of China to six different insecticides was evaluated by leaf dip method in the laboratory. The results sh...Resistance of five field populations of Mythimna separata（Walker） collected from Shaanxi and Shanxi provinces of China to six different insecticides was evaluated by leaf dip method in the laboratory. The results showed that all populations were relatively sensitive to emamectin benzoate with a resistance ratio（RR） of 0.583–1.583 folds. All populations showed susceptible or low level resistance to chlorantraniliprole and beta-cypermethrin. Compared with a relatively susceptible strain of M. separata, the resistance level of the whole populations ranged from susceptible to moderate to chlorpyrifos and lambda-cyhalothrin, moderate to high to phoxim（RR=19.367–70.100） except for population from Sanyuan County（RR=2.567）. Pair-wise correlation analysis among different insecticides indicated that chlorpyrifos has a significantly positive and significant correlation with emamectin benzoate. Chlorantraniliprole didn＇t have significant correlation with emamectin benzoate, chlorpyrifos and phoxim. Therefore, emamectin benzoate, chlorantraniliprole and beta-cypermethrin are recommended to control oriental armyworm. Meanwhile, to postpone the occurrence and development of insecticide resistance in Shaanxi and Shanxi provinces, alternative and rotational application of insecticides between chlorantraniliprole and emamectin benzoate or chlorpyrifos is necessary.展开更多
Mythimna separata（Walker） is an important pest which can cause serious damages to cereal crops. In the past two decades, several heavy outbreaks have taken place in northern China. In order to develop a fine-scale m...Mythimna separata（Walker） is an important pest which can cause serious damages to cereal crops. In the past two decades, several heavy outbreaks have taken place in northern China. In order to develop a fine-scale method of forecasting outbreaks, population data were collected in northern China using searchlight traps and ground light traps. A background weather pattern analysis and trajectory analysis were performed via the Weather Research and Forecast（WRF） and FLEXPART models. Our results showed that heavy migration of first-generation M. separata appeared in northern China in 2013. In Yanqing District, Beijing, the cumulative number of captured adults in searchlight traps was around 250000 and the daily maximum for trapped moths was 86000. During the peak period, the majority of M. separata moths arrived after 00：00 every night. The sex ratio（female：male） at each monitoring site was greater than 1 and greatly fluctuated with population dynamics. During the migration peak, prevailing downdraft winds benefited M. separata moths to land passively. Trajectory simulation showed that immigrants were from Anhui, Jiangsu and Hubei provinces and most of them could continue to fly into the northeastern regions of China. These results provide technical support for fine-scale forecasting of the outbreak of M. separata at meso-and micro-scale.展开更多
Migratory insects make diverse adaptive strategies in response to changes in external environment. Temperature has an impact on the survival, development, reproduction, and migration initiation of insects. Previous re...Migratory insects make diverse adaptive strategies in response to changes in external environment. Temperature has an impact on the survival, development, reproduction, and migration initiation of insects. Previous research has primarily been focused on the effects of constant temperature on populations, but changing temperature has received less attention. Three constant temperature treatments（20, 25 and 30℃） and three pupal-alternating temperature treatments（20–25, 25–20 and 25–30℃） were set up to study the relationship between temperature and population development by age-stage, two-sex life table analysis in the oriental armyworm, Mythimna separata Walker, a notorious migratory pest in grain crops. The 25℃ treatment was considered optimal with 20 and 30℃ as low suitable temperature and high temperatures, respectively. The survival rate was relatively low before third instar larvae at 20℃（63.0%） and 20–25℃（70.1%）, and extreme low after pupal stage at 30℃（20.6%）. Developmental duration of each stage was negatively correlated with temperature. The adult preoviposition period, when most migratory insects initiate migration, was the shortest at 25℃（2.69d） but was lengthened at both low suitable（7.48d for 20℃, 6.91d for 25–20℃ and 4.57d for 20–25℃） and high temperatures（3.74d for 25–30℃ and 5.00d for 30℃）. Both low suitable and high temperature decreased lifetime fecundity, net reproductive rate and the intrinsic rate of increase, with variability observed across developmental duration and stage during non-optimal temperature. The results expand knowledge of the relationship between changing temperature and armyworm population development, and adaptive strategies in complex ambient environment.展开更多
The presence of adequate nectar sources along the migratory pathway is a prerequisite for moths of oriental armyworm, Mythimna separata, to reach target habitats and lay eggs. Identification of plant species and asses...The presence of adequate nectar sources along the migratory pathway is a prerequisite for moths of oriental armyworm, Mythimna separata, to reach target habitats and lay eggs. Identification of plant species and assessment of their suitability as wild nectar sources along the summer migration pathway of adult M. separata are critical steps in making effective forecasts of second-and third-generation armyworm outbreaks in North China. We explored five aspects of moth-nectar source relationships：（1） Field investigations in 2014 and 2015 showed that the florescence of chaste tree, Vitex negundo var. heterophylla, a primary nectar plant in apiculture, coincided with the summer migration of oriental armyworm moths. The flowers of chaste tree opened day and night and M. separata moths were found actively flying around and resting on tree.（2） Identification of moth-borne pollen by scanning electronic microscopy（SEM） micrographs in 2015 and 2016 revealed that 15.4% of 369 moths trapped by blacklight traps, 17.1% of 557 moths captured by vertical-pointing searchlight traps and 24.4% of 311 moths caught by pheromone traps were found with pollen attached to their proboscis. A total of 228 pollen-carrying individuals out of 1237 armyworm moths were captured by the three types of traps. The three highest percentages of pollen-bearing armyworm moths were carrying pollen of Toona sp.（59.65%）, Ligustrum sp.（27.19%） and Syringa sp.（4.39%）. In total, 14 types of pollen were detected where three were identified to species, 10 to genus and one as an unknown species.（3） Analysis of geographical distribution, flowering periods and relative abundances of candidate nectar plants suggested that Chinese toon, Toona sinensis, and privet, Ligustrum lucidum, were two important nectar plant species.（4） Analysis on relationship between pollen and ovarian development showed that 14, 15 and 10 females carrying pollen of T. sinensis had ovaries at developmental stages Ⅰ, Ⅱ and Ⅲ, respectively. Many T. sinensis pollen grains were present on the proboscises of female moths.（5） Comparison of trap effectiveness between blacklight and vertical-pointing searchlight traps indicated blacklight traps caught the highest proportion（35.2%） of female in ovarian stage Ⅴ, whereas vertical-pointing searchlight traps caught the highest proportion（43.5%） of female in ovarian stage I with additional proportions of decreasing percentages for stages Ⅱ, Ⅲ and Ⅳ. Integrated analysis on these five aspects suggests that T. sinensis is an important, suitable summer nectar source that potentially influences migration and reproduction of M. separata moths andthus contributes to outbreaks of this pest. The vertical-pointing searchlight trap was the most effective tool for monitoring the migratory flight of adult M. separata. Privet, Ligustrum lucidum, and clove, Syringa sp., are possible suitable summer nectar plants that need further study to elucidate their importance. The reason why field investigation results on chaste tree differed from the results of moth-borne pollen analyses was discussed.展开更多
Effects of cycling and constant temperature on development and reproduction of the armyworm, Mythimna separata (Walker) were investigated by rearing the insects on the artificial diet under temperatures covering low(1...Effects of cycling and constant temperature on development and reproduction of the armyworm, Mythimna separata (Walker) were investigated by rearing the insects on the artificial diet under temperatures covering low(16-24℃ vs. 20 ℃ ), medial(20-28℃ vs. 24℃ ) and high(24-32 ℃ vs. 28 ℃) regions. In the low region, all the immature stages of the insect developed significantly faster under alternating temperatures than at corresponding constant temperatures. For the medial region, their development was little affected by variable temperatures. For the high region, developmental durations tended to be longer under cycling temperatures except egg stage.Mean fecundities of the adult moths markedly increased under cycling temperatures as compared with those at respective constant temperature in all regions.Possible reasons for effect of alternating temperatures on insect development are discussed in some details.展开更多
To clarify association between armyworm（Mythimna separata） damage level and the corn growth and weed occurrence, we investigated corn plant height, stem diameter and vigor as well as weed coverage and biomass. The i...To clarify association between armyworm（Mythimna separata） damage level and the corn growth and weed occurrence, we investigated corn plant height, stem diameter and vigor as well as weed coverage and biomass. The investigations were conducted at three locations of Shaanxi Province, China which were suffered seriously from armyworm. Significant correlations were found between the parameters analyzed. At stunted corn growth and presence of plenty of weeds, the armyworm damage tended to be heavy; oppositely, when corn grew well and weed density were low, armyworm harm was the minimal. Therefore, corn growing status and weed density can significantly affect armyworm damage level. Our results imply that promoting corn growth and timely removal of weeds are conducive to reducing armyworm occurrence.展开更多
基金funded by the Science and Technology Program of Guizhou Province,China([2020]IZ022)the National Natural Science Foundation of China(32160641)+1 种基金the Science&Technology Support Program of Guizhou Province,China(2023–055)the Training Program of Guizhou University,China([2019]32 and[2019]45)。
文摘Microvitellogenin(mVg)belongs to the lepidopteran-specific lipoprotein_11 super family and is thought to be involved in insect reproduction.However,the function of mVg in reproduction has not been established.In this study,we identified and characterized MsmVg in Mythimna separata,a destructive insect pest of grain crops.MsmVg is comprised of a 1,310 bp open reading frame(ORF)encoding 437 amino acids.Structural analysis showed that MsmVg contains three conserved domains in the lipoprotein_11 super family,including the all-α-N-terminal domain(NTD),a Pseudomonas putida homologous domain(PPD),and an all-β-C-terminal domain(CTD).MsmVg was highly expressed in mature female adults and enriched in the ovaries of 3-day-old female adults.Disruption of MsmVg by RNA interference did not change the expression of MsmVg,vitellogenin(MsVg)or the vitellogenin receptor(MsVgR)in fat bodies,but it inhibited their transcription in ovaries.Phenotype analysis showed that knockdown of MsmVg did not affect yolk deposition in ovaries,but impaired eggshell formation and led to a reduction in the reproductive capacity.Furthermore,knockdown of MsmVg significantly inhibited the expression of genes associated with eggshell formation(MsChP1-3 and MsFcP3C).Taken together,these data suggest that MsmVg plays an important role in female reproduction by affecting eggshell formation in M.separata,which provides a potential target for managing this insect pest.
基金supported by the National Natural Science Foundation of China(32130089)the Norwegian Research Council(324379)。
文摘In insects,the number and specificity of antennal lobe glomeruli often reflect the number and diversity of expressed chemosensory genes,which are linked to its ecological niche and specific olfactory needs.The oriental armyworm,Mythimna separata,is an important and common lepidopteran pest of cereal crops.Given its reliance on the olfactory system for crucial behaviors,understanding the evolutionary potential of this system requires a thorough characterization of the anatomical structure of the primary olfactory center.Here,we systematically identified all antennal lobe glomeruli of M.separata based on synaptic antibody immunostaining and mass staining of the olfactory sensory neurons.A total of 69 glomeruli were identified in females and 65 in males,and an intuitive nomenclature based on glomerular positions was applied.Our findings uncovered some sex-specific glomeruli in this species.There were ten female-specific glomeruli and three male-specific glomeruli,except for the macroglomerular complex(MGC)units,with a notable observation that the female labial pit organ glomerulus was larger than its male counterpart.Additionally,we identified four antennal-lobe tracts(ALTs)and retrograde labeling from the calyx revealed that all glomeruli were innervated by the medial ALT projection neurons.The comparison of the olfactory system structures between M.separata and sympatric moths supports their evolutionary convergence in noctuid moths.These results collectively lay the foundation for future studies on olfactory processing in M.separata.
文摘The changes of climate factors and the number of Mythimna separata in Menghai County during 1982 -2007 were analyzed, and the relationship between them was discussed. The results showed that there was certain relationship between the outbreak of M. separata and the climate conditions. There was extremely significant correlation between temperature and the number of M. separata. The temperature affected the occurfence amount of M. separata and the regression equation was y=2.691 x-57.123（ P^2 =0.110）. There was no significant correlation between the relative humidity and the amount of M. separata. But the rainfall had significant relationship with the large occurrence of M. separata.
基金supported by the National Key Research and Development Program of China(2022YFD1400600)the National Natural Science Foundation of China(32172397,32472540,31871951 and 31672019)+1 种基金the China Agriculture Research System of MOF and MARA(CARS-22)the Natural Science Foundation of Beijing,China(6172030)。
文摘Migratory insect pests tend to suddenly immigrate into new habitats over a short period to simultaneously lay eggs in clusters,resulting in gregarious larvae that cause severe damage to crops.These aggregated larvae can adapt well to various natural enemies and pathogens in their new habitats,but how their resistance might be enhanced and its immunological significance remain unknown.Here,we examined how infection by a pathogen and a parasitic fly affect the immune response and migratory behavior in two phases of the oriental armyworm,Mythimna separata,which differ dramatically in their flight capacity and fecundity.The gregarious larvae displayed greater resistance than solitary larvae to the challenges of both the entomopathogenic fungus Metarhizium anisopliae and the parasitoid Exorista civilis.In response to a challenge by M.anisopliae,gregarious larvae exhibited more pronounced increases in phenoloxidase(PO)activity and lysozyme activity than solitary larvae.Furthermore,in addition to the greater PO and lysozyme activities,the levels of dopamine and 5-hydroxytryptamine(5-HT)were also greater in challenged gregarious and solitary larvae.Injection of dopamine(or 5-HT)significantly enhanced PO activity,lysozyme activity,antibacterial activity and larval survival.Subsequently,there was a significant increase in the flight capacity of adults derived from gregarious larvae challenged by M.anisopliae;while no significant variation was observed in the adults from challenged solitary larvae.The preoviposition period,oviposition period and fecundity were not significantly affected by M.anisopliae,regardless of whether the larvae were gregarious or solitary.These results provide new insights into the relationship between migration and immunity in insects,and their behavior after immunization.
基金supported by the Special Fund for Agroscientific Research in the Public Interest of China (201403031)the Research Project Program of Agricultural Science and Technology innovation Transformation in Shaanxi Province, China
文摘Resistance of five field populations of Mythimna separata（Walker） collected from Shaanxi and Shanxi provinces of China to six different insecticides was evaluated by leaf dip method in the laboratory. The results showed that all populations were relatively sensitive to emamectin benzoate with a resistance ratio（RR） of 0.583–1.583 folds. All populations showed susceptible or low level resistance to chlorantraniliprole and beta-cypermethrin. Compared with a relatively susceptible strain of M. separata, the resistance level of the whole populations ranged from susceptible to moderate to chlorpyrifos and lambda-cyhalothrin, moderate to high to phoxim（RR=19.367–70.100） except for population from Sanyuan County（RR=2.567）. Pair-wise correlation analysis among different insecticides indicated that chlorpyrifos has a significantly positive and significant correlation with emamectin benzoate. Chlorantraniliprole didn＇t have significant correlation with emamectin benzoate, chlorpyrifos and phoxim. Therefore, emamectin benzoate, chlorantraniliprole and beta-cypermethrin are recommended to control oriental armyworm. Meanwhile, to postpone the occurrence and development of insecticide resistance in Shaanxi and Shanxi provinces, alternative and rotational application of insecticides between chlorantraniliprole and emamectin benzoate or chlorpyrifos is necessary.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest,China(201403031)the National Natural Science Foundation of China(31571998)+1 种基金the earmarked fund for China Agriculture Research System(CARS-03)the National Key Research and Development Program of China(2016YFD0300702)
文摘Mythimna separata（Walker） is an important pest which can cause serious damages to cereal crops. In the past two decades, several heavy outbreaks have taken place in northern China. In order to develop a fine-scale method of forecasting outbreaks, population data were collected in northern China using searchlight traps and ground light traps. A background weather pattern analysis and trajectory analysis were performed via the Weather Research and Forecast（WRF） and FLEXPART models. Our results showed that heavy migration of first-generation M. separata appeared in northern China in 2013. In Yanqing District, Beijing, the cumulative number of captured adults in searchlight traps was around 250000 and the daily maximum for trapped moths was 86000. During the peak period, the majority of M. separata moths arrived after 00：00 every night. The sex ratio（female：male） at each monitoring site was greater than 1 and greatly fluctuated with population dynamics. During the migration peak, prevailing downdraft winds benefited M. separata moths to land passively. Trajectory simulation showed that immigrants were from Anhui, Jiangsu and Hubei provinces and most of them could continue to fly into the northeastern regions of China. These results provide technical support for fine-scale forecasting of the outbreak of M. separata at meso-and micro-scale.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest of China (201403031)
文摘Migratory insects make diverse adaptive strategies in response to changes in external environment. Temperature has an impact on the survival, development, reproduction, and migration initiation of insects. Previous research has primarily been focused on the effects of constant temperature on populations, but changing temperature has received less attention. Three constant temperature treatments（20, 25 and 30℃） and three pupal-alternating temperature treatments（20–25, 25–20 and 25–30℃） were set up to study the relationship between temperature and population development by age-stage, two-sex life table analysis in the oriental armyworm, Mythimna separata Walker, a notorious migratory pest in grain crops. The 25℃ treatment was considered optimal with 20 and 30℃ as low suitable temperature and high temperatures, respectively. The survival rate was relatively low before third instar larvae at 20℃（63.0%） and 20–25℃（70.1%）, and extreme low after pupal stage at 30℃（20.6%）. Developmental duration of each stage was negatively correlated with temperature. The adult preoviposition period, when most migratory insects initiate migration, was the shortest at 25℃（2.69d） but was lengthened at both low suitable（7.48d for 20℃, 6.91d for 25–20℃ and 4.57d for 20–25℃） and high temperatures（3.74d for 25–30℃ and 5.00d for 30℃）. Both low suitable and high temperature decreased lifetime fecundity, net reproductive rate and the intrinsic rate of increase, with variability observed across developmental duration and stage during non-optimal temperature. The results expand knowledge of the relationship between changing temperature and armyworm population development, and adaptive strategies in complex ambient environment.
基金funded by the project under the National Department of Public Benefit Research Foundation of China (201403031)
文摘The presence of adequate nectar sources along the migratory pathway is a prerequisite for moths of oriental armyworm, Mythimna separata, to reach target habitats and lay eggs. Identification of plant species and assessment of their suitability as wild nectar sources along the summer migration pathway of adult M. separata are critical steps in making effective forecasts of second-and third-generation armyworm outbreaks in North China. We explored five aspects of moth-nectar source relationships：（1） Field investigations in 2014 and 2015 showed that the florescence of chaste tree, Vitex negundo var. heterophylla, a primary nectar plant in apiculture, coincided with the summer migration of oriental armyworm moths. The flowers of chaste tree opened day and night and M. separata moths were found actively flying around and resting on tree.（2） Identification of moth-borne pollen by scanning electronic microscopy（SEM） micrographs in 2015 and 2016 revealed that 15.4% of 369 moths trapped by blacklight traps, 17.1% of 557 moths captured by vertical-pointing searchlight traps and 24.4% of 311 moths caught by pheromone traps were found with pollen attached to their proboscis. A total of 228 pollen-carrying individuals out of 1237 armyworm moths were captured by the three types of traps. The three highest percentages of pollen-bearing armyworm moths were carrying pollen of Toona sp.（59.65%）, Ligustrum sp.（27.19%） and Syringa sp.（4.39%）. In total, 14 types of pollen were detected where three were identified to species, 10 to genus and one as an unknown species.（3） Analysis of geographical distribution, flowering periods and relative abundances of candidate nectar plants suggested that Chinese toon, Toona sinensis, and privet, Ligustrum lucidum, were two important nectar plant species.（4） Analysis on relationship between pollen and ovarian development showed that 14, 15 and 10 females carrying pollen of T. sinensis had ovaries at developmental stages Ⅰ, Ⅱ and Ⅲ, respectively. Many T. sinensis pollen grains were present on the proboscises of female moths.（5） Comparison of trap effectiveness between blacklight and vertical-pointing searchlight traps indicated blacklight traps caught the highest proportion（35.2%） of female in ovarian stage Ⅴ, whereas vertical-pointing searchlight traps caught the highest proportion（43.5%） of female in ovarian stage I with additional proportions of decreasing percentages for stages Ⅱ, Ⅲ and Ⅳ. Integrated analysis on these five aspects suggests that T. sinensis is an important, suitable summer nectar source that potentially influences migration and reproduction of M. separata moths andthus contributes to outbreaks of this pest. The vertical-pointing searchlight trap was the most effective tool for monitoring the migratory flight of adult M. separata. Privet, Ligustrum lucidum, and clove, Syringa sp., are possible suitable summer nectar plants that need further study to elucidate their importance. The reason why field investigation results on chaste tree differed from the results of moth-borne pollen analyses was discussed.
文摘Effects of cycling and constant temperature on development and reproduction of the armyworm, Mythimna separata (Walker) were investigated by rearing the insects on the artificial diet under temperatures covering low(16-24℃ vs. 20 ℃ ), medial(20-28℃ vs. 24℃ ) and high(24-32 ℃ vs. 28 ℃) regions. In the low region, all the immature stages of the insect developed significantly faster under alternating temperatures than at corresponding constant temperatures. For the medial region, their development was little affected by variable temperatures. For the high region, developmental durations tended to be longer under cycling temperatures except egg stage.Mean fecundities of the adult moths markedly increased under cycling temperatures as compared with those at respective constant temperature in all regions.Possible reasons for effect of alternating temperatures on insect development are discussed in some details.
基金supported by the National Public Welfare Industry(Agriculture)Scientific Research of China(201403031)the National Key Research and Development Program of China(2017YFD0201807)the Project of Agricultural Science and Technology Innovation Transformation in Shaanxi Province,China
文摘To clarify association between armyworm（Mythimna separata） damage level and the corn growth and weed occurrence, we investigated corn plant height, stem diameter and vigor as well as weed coverage and biomass. The investigations were conducted at three locations of Shaanxi Province, China which were suffered seriously from armyworm. Significant correlations were found between the parameters analyzed. At stunted corn growth and presence of plenty of weeds, the armyworm damage tended to be heavy; oppositely, when corn grew well and weed density were low, armyworm harm was the minimal. Therefore, corn growing status and weed density can significantly affect armyworm damage level. Our results imply that promoting corn growth and timely removal of weeds are conducive to reducing armyworm occurrence.
