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    昆虫合辑Plant Protection—Entomolgy

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    Applying a salinity response function and zoning saline land for three field crops: a case study in the Hetao Irrigation District, Inner Mongolia, China
    TONG Wen-jie1, CHEN Xiao-li2, WEN Xin-ya1, CHEN Fu1, ZHANG Hai-lin1, CHU Qing-quan1, Shadrack Batsile Dikgwatlhe1
    2015, 14 (1): 178-189.   DOI: 10.1016/S2095-3119(14)60761-9
    Abstract1862)      PDF in ScienceDirect      
    Salinity is one of the major abiotic factors affecting the growth and productivity of crops in Hetao Irrigation District, China. In this study, the salinity tolerances of three local crops, wheat (Triticum aestinum L.), maize (Zea mays L.) and sunflower (Helianthus annuus L.), growing in 76 farm fields are evaluated with modified discount function. Salinity ecological zones appropriate for these local crops are characterized and a case study is presented for crop salinity ecological zoning. The results show that the yield reductions of wheat, maize and sunflower when grown in saline soils are attributed primarily to a reduction in spikelet number, 1 000-grain weight and seed number per head, respectively. Sunflower is the most tolerant crop among the three which had a salinity tolerance index (ST-index) of 12.24, followed by spring maize and spring wheat with ST-Indices of 9.00 and 7.43, respectively. According to the crop salinity tolerance results, the arable land in the Heping Village of this district was subdivided into four salinity ecological zones: the most suitable, suitable, sub-suitable and unsuitable zones. The area proportion of the most suitable zone for wheat, maize and sunflower within the Heping Village was 27.5, 46.5 and 77.5%, respectively. Most of the most suitable zone occurred in the western part of the village. The results of this study provide the scientific basis for optimizing the local major crop distribution and improving cultural practices management in Hetao Irrigation District.
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    Rice cultivation changes and its relationships with geographical factors in Heilongjiang Province, China
    LU Zhong-jun, SONG Qian, LIU Ke-bao, WU Wen-bin, LIU Yan-xia, XIN Rui, ZHANG Dong-mei
    2017, 16 (10): 2274-2282.   DOI: 10.1016/S2095-3119(17)61705-2
    Abstract624)      PDF in ScienceDirect      
    Rice planting patterns have changed dramatically over the past several decades in northeast China (NEC) due to the combined influence of global change and agricultural policy.  Except for its great implications for environmental protection and climate change adaption, the spatio-temporal changes of rice cultivation in NEC are not clear.  In this study, we conducted spatio-temporal analyses of NEC’s major rice production region, Heilongjiang Province, by using satellite-derived rice cultivation maps.  We found that the total cultivated area of rice in Heilongjiang Province increased largely from 1993 to 2011 and it expanded spatially to the northern and eastern part of the Sanjiang Plain.  The results also showed that rice cultivation areas experienced a larger increase in the region managed by the Reclamation Management Bureau (RMB) than that managed by the local provincial government.  Rice cultivation changes were closely related with those geographic factors over the investigated periods, represented by the geomorphic (slope), climatic (accumulated temperature), and hydrological (watershed) variables.  These findings provide clear evidence that crop cultivation in NEC has been modified to better cope with the global change.
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    Identification and characterization of a TLR13 gene homologue from Laodelphax striatellus involved in the immune response induced by rice stripe virus
    ZHOU Xue, HU Jia, FU Mei-li, JIN Ping, ZHANG Yun-ye, XIANG Ying, LI Yao, MA Fei
    2020, 19 (1): 183-192.   DOI: 10.1016/S2095-3119(19)62795-4
    Abstract122)      PDF in ScienceDirect      
    Toll-like receptors (TLRs) are the critical superfamily homologues that initiate sensing of the invasion of pathogens by the Toll pathway.  As one of several intracellular nucleic acid-sensing TLRs, TLR13 is activated by an unmethylated motif present in the large ribosomal subunit of bacterial RNA.  However, little attention has been paid to the function of TLR13 gene homologue from Laodelphax striatellus (designated as LsToll-13) in the immune response to rice stripe virus (RSV).  Herein, LsToll-13 was cloned and characterized using RACE-PCR.  Phylogenetic analysis showed that LsToll-13 was clustered with the TLR13 from six insects.  Real-time PCR analysis demonstrated that the expression level of LsToll-13 was significantly reduced in L.?striatellus with RSV infection compared with that in the naive strain.  When the expression of LsToll-13 was significantly up-regulated at 6 h after bacterial infection, the expression of ribonucleoprotein (RNP) indicated that the RSV titer in the host insect was significantly suppressed.  Upon knockdown of LsToll-13, using RNA interference (RNAi) in L.?striatellus, the expression level of RNP was significantly increased with enhanced RSV accumulation, suggesting that LsToll-13 potentially protects L.?striatellus from RSV infection.  Taken together, our results indicated that LsToll-13 might be involved in the immune response of L.?striatellus to RSV infection, and provided a new insight into further elucidating the molecular mechanisms of complex pathogen-host interactions and integrative pest management.
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    Exploiting push-pull strategy to combat the tea green leafhopper based on volatiles of Lavandula angustifolia and Flemingia macrophylla
    HAN Shan-jie, WANG Meng-xin, WANG Yan-su, WANG Yun-gang, CUI Lin, HAN Bao-yu
    2020, 19 (1): 193-203.   DOI: 10.1016/S2095-3119(19)62778-4
    Abstract113)      PDF in ScienceDirect      
    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, MeSA, 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 MeSA 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. 
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    Effects of Paranosema locustae (Microsporidia) on the development and morphological phase transformation of Locusta migratoria (Orthoptera: Acrididae) through modulation of the neurotransmitter taurine
    LI Ao-mei, YIN Yue, ZHANG Yu-xin, ZHANG Liu, ZHANG Kai-qi, SHEN Jie, TAN Shu-qian, SHI Wang-peng
    2020, 19 (1): 204-210.   DOI: 10.1016/S2095-3119(19)62637-7
    Abstract65)      PDF in ScienceDirect      
    Neurotransmitters are important in the maintenance of phase transformation of Locusta migratoria (Arthropoda: Orthoptera).  Here, the effects of the entomopathogen Paranosema locustae on the neurotransmitter taurine in migratory locusts were studied using biochemical methods.  After inoculation with P. locustae, the taurine content of infected locusts significantly declined, but F/C values (ratio between the length of hind femur and the width of the head of locust) increased significantly, compared to healthy locusts.  Meanwhile, F/C values of infected locusts that were injected with 2 µg of taurine showed no significant differences from those of healthy locusts, demonstrating that supplemental taurine inhibited the changes in morphological phase caused by P. locustaeParanosema locustae infection also caused longer developmental durations and lower body weights of locusts, but these changes were unaffected after injection with taurine.  These results provided new insights into the mechanisms by which microsporidian parasites affected their locust hosts.
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    pH influences the profiles of midgut extracts in Cnaphalocrocis medinalis (Guenée) and its degradation of activated Cry toxins
    YANG Ya-jun, XU Hong-xing, WU Zhi-hong, LU Zhong-xian
    2020, 19 (3): 775-784.   DOI: 10.1016/S2095-3119(19)62837-6
    Abstract51)      PDF in ScienceDirect      
    Midgut extracts play crucial roles in food digestion and detoxification.  We evaluated the effect of pH on the profiles of the midgut extracts in rice leaffolder, Cnaphalocrocis medinalis and the degradation of activated Bt-toxins by the midgut extracts under different pH conditions.  Total protease activity increased slightly with the increase with the simulated pH in the midgut extracts and the maximal protease activity was observed at pH 10.5, while an upward trend was observed as the pH of reaction buffer increased.  Activity of chymotrypsin-like enzymes increased with pH, both in the buffer and midgut extracts, while the activity of trypsin-like enzyme was unaffected.  Degradation of the activated Cry2A by the midgut extracts enhanced as the pH increased.  Cry2A was fully degraded into smaller segments at pH 9.0–10.5.  Activated Cry1C protein at pH 9.0–10.5 was partially degraded by the midgut extracts.  Activated Cry1Aa and Cry1Ac were partially degraded into fragments by the midgut extracts at high pH.  These results will facilitate our further understanding of the interactions between C. medinalis and the Cry toxin.
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    Overwintering parasitism is positively associated with population density in diapausing larvae of Chilo suppressalis
    HUANG Xiao-long, JIANG Ting, WU Zhen-ping, ZHANG Wan-na, XIAO Hai-jun
    2020, 19 (3): 785-792.   DOI: 10.1016/S2095-3119(19)62815-7
    Abstract72)      PDF in ScienceDirect      
    The suppression of overwintering population is essential in integrated pest management, but little is known about the biological mortality factors that reduce the overwintering density of Chilo suppressalis.  Here, we examine the parasitism of overwintering larvae, and assume that key parasitoids strengthen the over-wintering population suppression.  The natural parasitism incidence and related dominant parasitoids in overwintering larvae were investigated in two successive winters, in 2015–2016 and 2016–2017.  Parasitism rates were also assessed in larvae collected from 15 different counties in 2016.  The results showed that the parasitism incidence and dominant parasitoids in overwintering C. suppressalis larvae were significantly different for different sampling dates and sites.  Overwintering larvae of C. suppressalis were mainly parasitized by Cotesia chilonis, and less often by Eriborus sinicus and Micrurogaster ssata.  Regression analysis indicated that the natural incidence of parasites in overwintering C. suppressalis larvae was positively correlated with the over-wintering larval density.  The current work provides support for overwintering pest management strategies by showing the effectiveness of parasitoid communities as a bio-mortality factor for suppressing overwintering density.
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    How does the arthropod–plant system respond to abrupt and gradual increases in atmospheric CO2?
    ZHENG Xiao-xu, WU Gang
    2020, 19 (4): 1159-1161.   DOI: 10.1016/S2095-3119(19)62880-7
    Abstract87)      PDF in ScienceDirect      
    Global warming caused by elevated carbon dioxide (CO2) is a major environmental and policy issue.  The current global average temperature has been elevated by 1°C since the industrial revolution, and it is likely to reach a temperature increase of 1.5°C between 2030 and 2052 (IPCC 2018).  Human-caused emission of CO2 is responsible for the greenhouse effect and the atmospheric CO2 concentration is higher now than at any other time in the past 500 000 years, and it continues to rise (Lüthi et al. 2008).  Impacts of arthropod–plant interactions on carbon dynamics and the global climate are important but often ignored.  For example, outbreaks of the mountain pine beetle, Dendroctonus ponderosae, in British Columbia during 2000–2020 will cause the release of an estimated 270 Mt carbon and convert the forest from a small carbon sink to a large carbon source (Kurz et al. 2008).   The annual carbon release due to outbreaks of this beetle is almost equivalent to the annual carbon emission from all forest fires occurring in Canada over 1959–1999 (Kurz et al. 2008).
    Most studies of arthropod–plant interactions have focused on the effects of ambient CO2 or abruptly increasing CO2 concentrations.  In general, these studies show that elevated CO2 has a positive direct effect on plant photosynthesis and photosynthate production (Bezemer and Jones 1998; Kim et al. 2015; Andresen et al. 2018; Thomey et al. 2019).  Most scientists expect C3 plants to benefit from this additional CO2 and outcompete C4 species, because the efficiency of C3 photosynthesis increases with increasing CO2 concentration to a far greater extent than it does in C4 photosynthesis (Hovenden and Newton 2018; Reich et al. 2018).  Yan et al. (2020) found that elevated CO2 increased photosynthetic rate, nodule number, yield and total phenolic content of Medicago truncatula.  Dong et al. (2018a) reported that elevated CO2 promoted the yield and nutritional quality of cucumber (Cucumis sativus L.).  After conducting a meta-analysis using 57 articles consisting of 1 015 observations, they found that elevated CO2 increased the concentrations of fructose, glucose, total phenols, and total flavonoids in the edible parts of vegetables by 14.2, 13.2, 8.9, and 45.5%, respectively, but decreased the concentrations of protein and nitrate, by 9.5 and 18.0%, respectively (Dong et al. 2018b).  Robinson et al. (2012) reviewed the evidence from 170 studies and concluded that plant biomass, C:N ratio, total phenolics and flavonoids increase under elevated CO2, while N-based secondary metabolites and plant terpenoid concentrations decrease.  Being an important limiting factor for phytophagous arthropods, changes in foliar C-based secondary metabolites (e.g., condensed tannins and phenolics) and N-based chemicals may have major effects on arthropod performance.
    Numerous studies have found that elevated CO2 indirectly influences arthropod performance via the changes in plant chemical composition (Ge et al. 2010; Xu et al. 2013; Wu 2014; Sun et al. 2018).  Wen et al. (2019) observed a significantly longer larval duration and lower fecundity of Nilaparvata lugens in elevated CO2.  After analyzing 122 studies, Robinson et al. (2012) concluded that elevated CO2 increases arthropod survival, abundance and relative consumption rate, but it reduces fecundity, relative growth rate and adult weight.  Many chewing pests, such as cotton bollworm (Helicoverpa armigera) and gypsy moth, exhibited lower fecundity, consumption rate and finite rate under elevated CO2 (Foss et al. 2013; Liu et al. 2017).  The sucking pests, however, displayed varied responses to elevated CO2.  For example, in aphids, the responses to elevated CO2 in terms of fecundity, development and population growth varied between different species, different hosts or even different genotypes of the same host (Sudderth et al. 2005; Gao et al. 2008; Guo et al. 2013).  The studies documented above indicated that the chewing arthropods and sap feeders employ different strategies in response to elevated CO2
    While it is clear that arthropod–plant interactions are affected by atmospheric CO2 concentrations, it is currently uncertain whether an abrupt increase in CO2 causes similar responses as the gradual increase has been observed since the industrial revolution.  A recent study of Bromus inermis (a perennial grass) and its associated arbuscular mycorrhizal fungi (AMF) shows that abrupt and gradual CO2 change regimes may not elicit the same response (Klironomos et al. 2005).  In a long-term 6-year experiment in which plants were exposed to three CO2 regimes (ambient CO2, gradual increase in CO2, and abrupt increase in CO2) for 21 successive generations, more AMF taxa were lost when CO2 was raised abruptly than when a gradual increase of the same magnitude was implemented.  The abrupt change in CO2 resulted in a significant change in mycorrhizal diversity in the first generation, although little change occurred in subsequent generations.  Species richness of AMF was similar in the gradual and ambient CO2 treatments but was significantly lower in the abrupt CO2 change treatment (Klironomos et al. 2005).  It is not known whether these effects would be similar in an intact field experiment where fungal meta-community dynamics may come into play and mediate any local species extinctions.  A comparable long-term 3-year experiment (Wu et al., unpublished data) investigating impacts of abrupt vs. gradual increases in CO2 on life-history traits of N. lugens feeding on rice over 16 successive generations, indicated that the gradual increase in CO2 treatment can promote the growth and physiological metabolism of N. lugens relative to the abrupt CO2 increase treatment.  So, the effects of abrupt and gradual CO2 change regimes on arthropods, plants and their associated organisms could differ because the changes affecting organisms are initially the greatest for the first subsequent generation in the abrupt regime, while the evolutionary responses of the interacting organisms differ between the two regimes.
    Current generalizations about the effects of increasing atmospheric CO2 on arthropod–plant interactions are mainly based on experiments using the abrupt approach.  However, a major assumption of these approaches has not been tested, i.e., whether a single-step increase in CO2 yields similar responses in arthropod–plant systems as a gradual increase over several decades.  If a sudden increase in CO2 does not yield a response that is similar to a gradual increase of the same magnitude, some of these generalizations could be affected.  Hovenden and Newton (2018) considered that long-term experiments show unexpected plant responses to elevated CO2 concentrations.  Therefore, most current research may overestimate the impact of abrupt changes in CO2 concentrations on the arthropod–plant systems.  We must be cautious when designing experiments and explaining the effects of CO2 concentrations on the arthropod–plant system, because the magnitudes of responses to environmental changes that are significantly more abrupt may be different than those that would occur in nature.  Therefore, other model systems and intact ecosystems should be used to understand how an increase in atmospheric CO2 influences interactions between arthropods and their host plants.
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    Effect of three insect-resistant maizes expressing Cry1Ie, Cry1Ab/Cry2Aj and Cry1Ab on the growth and development of armyworm Mythimna separata (Walker)
    SU Hong-hua, JIANG Tao, SUN Yu, GU Hui-jie, WU Jiao-jiao, YANG Yi-zhong
    2020, 19 (7): 1842-1849.   DOI: 10.1016/S2095-3119(20)63162-8
    Abstract77)      PDF in ScienceDirect      
    Three transgenic maize events (IE09S034, Shuangkang 12–5 and C0030.3.5) produced Cry1Ie, Cry1Ab/Cry2Aj and G10-EPSPS, Cry1Ab and EPSPS, respectively, all of which target the Asian corn borer.  The oriental armyworm Mythimna separata (Walker) is the secondary target.  In this study, the effects of the three Bt maizes on the development and survival of armyworm were studied.  The results showed that IE09S034 had insecticidal activity against 1st instar larvae, and the survival rate of armyworm fed with Bt maize for 10 days was 46.2%, significantly lower than that of the control.  The larvae at 3rd–6th instar were more tolerant of the Bt toxin than the early instar larvae.  However, Shuangkang 12-5 had good insecticidal activity against 1st–5th instar larvae.  The mortality was nearly 100% when the larvae were fed with Shuangkang 12-5 before 3rd instar, and the toxin had quick-acting efficacy.  This event significantly inhibited the development of armyworm; that is, the larval duration of the 3rd and 4th instar larvae fed with Shuangkang 12-5 was prolonged by 4.5 and 3.0 days, respectively.  The pupal weight and egg number were also significantly lower than those of the control.  For C0030.3.5, it could control 1st–5th instar larvae effectively.  The mortality rates were all over 50% if 1st–3rd larvae were fed with this event.  The pupal weight of 4th–6th instar larvae fed with Bt maize were only 53.9, 56.8 and 54.6%, respectively, compared to that of the control.  The number of eggs laid was significantly less than the control.  The results indicate that all three transgenic maize events exhibit the potential to provide effective control of early instar larvae of armyworm, which can be commercialized in future to control lepidoptera pests such as Asian corn borer and armyworm.
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    Two farnesyl pyrophosphate synthases, GhFPS1–2, in Gossypium hirsutum are involved in the biosynthesis of farnesol to attract parasitoid wasps
    ZHANG Hong, HUANG Xin-zheng, JING Wei-xia, LIU Dan-feng, Khalid Hussain DHILOO, HAO Zhi-min, ZHANG Yong-jun
    2020, 19 (9): 2274-2285.   DOI: 10.1016/S2095-3119(20)63203-8
    Abstract105)      PDF in ScienceDirect      
    Sesquiterpenoids play an import role in the direct or indirect defense of plants.  Farnesyl pyrophosphate synthases (FPSs) catalyze the biosynthesis of farnesyl pyrophosphate, which is a key precursor of farnesol and (E)-β-farnesene.  In the current study, two FPS genes in Gossypium hirsutum, GhFPS1 and GhFPS2, were heterologously cloned and functionally characterized in a greenhouse setting.  The open reading frames for full-length GhFPS1 and GhFPS2 were each 1 029 nucleotides, and encoded two proteins of 342 amino acids with molecular weights of 39.4 kDa.  The deduced amino acid sequences of GhFPS1–2 showed high identity to FPSs of other plants.  Quantitative real-time PCR analysis revealed that GhFPS1 and GhFPS2 were highly expressed in G. hirsutum leaves, and were upregulated in methyl jasmonate (MeJA)-, methyl salicylate (MeSA)- and aphid infestation-treated cotton plants.  The recombinant proteins of either GhFPS1 or GhFPS2 plus calf intestinal alkaline phosphatase could convert geranyl diphosphate (GPP) or isopentenyl diphosphate (IPP) to one major product, farnesol.  Moreover, in electrophysiological response and Y-tube olfactometer assays, farnesol showed obvious attractiveness to female Aphidius gifuensis, which is an important parasitic wasp of aphids.  Our findings suggest that two GhFPSs are involved in farnesol biosynthesis and they play a crucial role in indirect defense of cotton against aphid infestation.
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    Effects of a novel mesoionic insecticide, triflumezopyrim, on the feeding behavior of rice planthoppers, Nilaparvata lugens and Sogatella furcifera (Hemiptera: Delphacidae)
    ZHU Jun, SUN Wen-qing, LI Yao, GE Lin-quan, YANG Guo-qing, XU Jian-xiang, LIU Fang
    2020, 19 (10): 2488-2449.   DOI: 10.1016/S2095-3119(20)63197-5
    Abstract80)      PDF in ScienceDirect      
    The rice planthoppers, Nilaparvata lugens and Sogatella furcifera, are important sap-sucking pests of rice in Asia.  The mesoionic insecticide triflumezopyrim was previously shown to be highly effective in controlling both N. lugens and S. furcifera.  In this study, electropenetrography (EPG) was used to evaluate the effect of three triflumezopyrim concentrations (LC10, LC50 and LC90) on the feeding behavior of N. lugens and S. furcifera.  EPG signals of planthoppes indicated that there were six different waveforms NP, N1, N2, N3, N4, and N5, which corresponded to non-penetration, stylet penetration into epidermis, salivation, extracellular movement of stylet, sap ingestion in phloem, and water ingestion in xylem during feeding.  Compared to untreated controls, triflumezopyrim at LC50 and LC90 prolonged the duration of the non-penetration period by 105.3 to 333.7%.  The probing frequencies of N. lugens exposed to triflumezopyrim at LC10 and LC50 were significantly increased; however, the probing frequencies of S. furcifera showed a significant decrease when exposed to triflumezopyrim at all concentrations.  Triflumezopyrim exposure prolonged the duration of salivation and shortened the duration of extracellular movement.  The duration of phloem sap ingestion decreased from 37.2 to 77.7% in the LC50 and LC90 treatments, respectively.  Differences in feeding behavior in response to triflumezopyrim and pymetrozine were minimal.  In summary, the results show that the LC50 and LC90 concentrations of triflumezopyrim inhibit the feeding activities of N. lugens and S. furcifera mainly by prolonging the duration of non-penetration and by shortening the duration of phloem sap ingestion, which may foster more efficient use of triflumezopyrim in Asia.
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    Molecular characteristics and temperature tolerance function of the transient receptor potential in the native Bemisia tabaci AsiaII3 cryptic species
    JI Shun-xia, SHEN Xiao-na, LIANG Lin, WANG Xiao-di, LIU Wan-xue, WAN Fang-hao, Lü Zhi-chuang
    2020, 19 (11): 2746-2757.   DOI: 10.1016/S2095-3119(20)63226-9
    Abstract70)      PDF in ScienceDirect      
    Insects are poikilothermic animals, and temperature is one of the most important abiotic factors affecting their spread and distribution.  For example, differences in thermal tolerance may underlie the significant differences in geographical distributions between the native AsiaII3 and invasive MED (Mediterranean) cryptic Bemisia tabaci species in China.  Transient receptor potential (TRP) channels are key components of the insect temperature perception system and act as molecular thermometers since they can be activated by specific changes in temperature.  In this study, we cloned and characterized the AsiaII3 BtTRP gene and revealed its functions in the response to thermal stress.  The full-length cDNA of BtTRP was 3 821 bp, with a 3 501-bp open reading frame encoding a 132.05-kDa protein.  Comparing the deduced amino acid sequences of AsiaII3 BtTRP and MED TRP revealed five amino acid differences.  In situ hybridization indicated that BtTRP might be widely expressed throughout the AsiaII3 adult body.  BtTRP mRNA expression reached the highest levels after exposure to mild thermal stimuli (12 and 35°C), showing that BtTRP expression can be induced by temperature stress.  Furthermore, the thermal tolerance of AsiaII3 after BtTRP dsRNA feeding was significantly lower than that of the control.  Taken together, the present study highlights the importance of TRP channels for B.?tabaci thermal resistance, and allows us to infer that the differences in amino acids between AsiaII3 and MED might cause the differences in thermal tolerance of these two cryptic species.  This study provides a new direction for investigating geographic distribution differences between invasive and native insects.
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    Cloning and functional characterization of two peptidoglycan recognition protein isoforms (PGRP-LC) in Bactrocera dorsalis (Diptera: Tephritidae)
    WEI Dong, WANG Zhe, XU Hui-qian, NIU Jin-zhi, WANG Jin-jun
    2020, 19 (12): 3025-3034.   DOI: 10.1016/S2095-3119(20)63202-6
    Abstract52)      PDF in ScienceDirect      
    The innate immune system of insects is the front line of self-defense against pathogen invasion.  Peptidoglycan recognition proteins (PGRPs) are important components and play key roles in insect immune systems by recognizing peptidoglycan (PGN) in bacterial cell walls.  We characterized two isoforms of the PGRP-LC gene, BdPGRP-LCa and BdPGRP-LCb, from Bactrocera dorsalis (Hendel), an important fruit and vegetable pest worldwide.  These two isoforms contain an open reading frames of 1 668 bp and 1 731 bp, encoding a protein of 555 and 576 amino acids, respectively.  Quantitative real-time PCR results showed that both transcripts were prominently expressed in midgut and fat body of B. dorsalis adult.  Inoculation of pathogens showed that both isoforms actively responded to Escherichia coli PGN.  We also observed a light response to Staphylococcus aureus PGN.  Upon Beauveria bassiana inoculation, the expression of BdPGRP-LCa was enhanced, but the expression of BdPGRP-LCb was suppressed.  Suppression of both transcripts by RNA interference led to increased mortality of flies challenged by E. coli, indicating that the two isoforms are involved in sensing Gram-negative bacterial infections.
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    Attraction of bruchid beetles Callosobruchus chinensis (L.) (Coleoptera: Bruchidae) to host plant volatiles
    WANG Hong-min, BAI Peng-hua, ZHANG Jing, ZHANG Xue-min, HUI Qin, ZHENG Hai-xia, ZHANG Xian-hong
    2020, 19 (12): 3035-3044.   DOI: 10.1016/S2095-3119(20)63237-3
    Abstract85)      PDF in ScienceDirect      
    Host-plant volatiles play an important role as cues for herbivores in search of resources, mates and oviposition sites in complex environments.  Plant volatile-based attractants can be developed for pest monitoring and control.  Previously, we indicated that mated female adults of Callosobruchus chinensis showed choice preference behavior toward 2-hexenal and benzaldehyde.  Our objective here was to investigate the synergistic effect of host-derived attractive volatiles in attracting C. chinensis under laboratory and field conditions in Shanxi Province, China.  We hypothesized that the ratio and concentration of volatiles derived from Vigna radiata play critical roles for C. chinensis in locating this host.  Therefore, we collected and identified the volatiles of mungbean by using headspace collection and GC-MS.  The effectiveness of different ratios and concentrations of two compounds (2-hexenal and benzaldehyde) that elicit C. chinensis searching behavior were examined in Y-tube olfactometer assays.  The combination of 300 μg μL–1 2-hexenal and 180 μg μL–1 benzaldehyde loadings exhibited a synergistic effect on attracting C. chinensis (82.35%).  Compared to control traps, the adults were significantly attracted to traps baited with blends, and more attraction to females than males was found for blend traps in the field experiments.  Our results suggest that blends of this specific concentration and ratio of benzaldehyde and 2-hexenal can be used in traps as attractants for C. chinensis monitoring and control in the field.
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    Performance and transcriptomic response of the English grain aphid, Sitobion avenae, feeding on resistant and susceptible wheat cultivars
    LAN Hao, ZHANG Zhan-feng, WU Jun, CAO He-he, LIU Tong-xian
    2021, 20 (1): 178-190.   DOI: 10.1016/S2095-3119(20)63349-4
    Abstract64)      PDF in ScienceDirect      
    Plant resistance against insects mainly depends on nutrient restriction and toxic metabolites, but the relative importance of nutrition and toxins remains elusive.  We examined performance, nutrition ingestion, and transcriptome response of the English grain aphid, Sitobion avenae, feeding on resistant Xiaoyan 22 (XY22) and susceptible Xinong 979 (XN979) wheat cultivars.  Aphids had lower body weight and fecundity when feeding on XY22 than on XN979, although the phloem sap of XY22 had a higher nutritive quality (in terms of amino acid:sucrose ratio).  Aphids feeding on XY22 also had a lower honeydew excretion rate than those on XN979, suggesting that aphids ingested less phloem sap from XY22.  The transcriptome data showed 600 differentially expressed genes (DEGs), and 11 of the top 20 KEGG pathways significantly enriched in DEGs were involved in nutrient metabolism.  We found 81 DEGs associated with the metabolism of sugars, lipids, and amino acids, 59 of which were significantly downregulated in aphids feeding on XY22.  In contrast, there were 18 DEGs related to detoxifying metabolism, namely eight UDP-glucuronosyltransferases, six cytochromes P450 monooxygenases, one glutathione S-transferase, two ATP-binding cassette transporters, and one major facilitator superfamily transporter; 12 of these were upregulated in the aphids feeding on XY22.  Our results indicated that both the quantity and quality of phloem nutrition available to aphids are critical for the growth and development of aphids, and the higher resistance of XY22 is mainly due to the reduction in phloem sap ingested by aphids, rather than toxic metabolites.
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    InvasionDB: A genome and gene database of invasive alien species
    HUANG Cong, LANG Kun, QIAN Wan-qiang, WANG Shu-ping, CAO Xiao-mei, HE Rui, ZHAN An-ran, CHEN Meng-yao, YANG Nian-wan, LI Fei
    2021, 20 (1): 191-200.   DOI: 10.1016/S2095-3119(20)63231-2
    Abstract172)      PDF in ScienceDirect      
    Invasive alien species (IAS) are species whose introduction to areas outside of their native range cause harm to economics, biodiversity, and the environment.  Understanding the genetic basis of invasiveness is critical for preventing invasion by an alien species and managing IAS with eco-friendly control methods.  In addition, uncovering the genomic features of IAS is essential for accurately predicting invasiveness.  However, even though increasing efforts have been devoted to sequencing the genomes of IAS, there is still not an integrated genome database for the invasive biology community.  Here, we first determined a list of invasive plants and animals by mining references and databases.  Then, we retrieved the genomic and gene data of these IAS, and constructed a database, InvasionDB.  InvasionDB encompasses 131 IAS genomes, 76 annotated IAS assemblies, and links these data to conventional functions such as searching for gene coding sequences and Pfam, KEGG, NR annotations, BLAST server, JBrowse, and downloads services.  Next, we analyzed 19 invasiveness-related gene families which confer invasiveness in insects.  To study the roles of noncoding RNA in invasiveness, we also annotated 135 494 miRNAs, 89 294 rRNAs, and 2 671 941 tRNAs from these IAS.  In summary, InvasionDB is useful for studying the invasiveness at the genomic level, and thus helps to develop novel management strategies to control IAS.
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    Effect of a near-zero magnetic field on development and flight of oriental armyworm (Mythimna separata)
    YAN Meng-meng, ZHANG Lei, CHENG Yun-xia, Thomas W. SAPPINGTON, PAN Wei-dong, JIANG Xing-fu
    2021, 20 (5): 1336-1345.   DOI: 10.1016/S2095-3119(20)63287-7
    Abstract48)      PDF in ScienceDirect      
    The geomagnetic field affects all living organisms on the Earth.  In this study we investigated the developmental and behavioral effects of rearing Mythimna separata in a near-zero magnetic field (<500 nT) compared to the local geomagnetic field (approximately 50 μT).  The near-zero magnetic field produced by a Helmholtz coil system significantly lengthened larval and pupal development durations, increased male longevity, and reduced pupal weight, female reproduction, and the relative expression level of the vitellogenin (Vg) gene in newly emerged females.  Moreover, the near-zero magnetic field had a considerable negative effect on the mating ratio of M. separata adults.  In addition, the moths in the near-zero magnetic field displayed less flight activity late in the night than those in the Earth’s normal geomagnetic field, indicating that the flight rhythm of M. separata may be affected by the near-zero magnetic field.  Reduction in magnetic field intensity may have negative effects on the development and flight of oriental armyworm, with consequent additional effects on its migration.
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    Molecular characterization of the ryanodine receptor from Adoxophyes orana and its response to lethal and sublethal doses of chlorantraniliprole
    SUN Li-na, LIU Yan-di, ZHANG Huai-jiang, YAN Wen-tao, YUE Qiang, QIU Gui-sheng
    2021, 20 (6): 1585-1595.   DOI: 10.1016/S2095-3119(20)63356-1
    Abstract75)      PDF in ScienceDirect      
    The insect ryanodine receptor (RyR) is a novel target of the anthranilic and phthalic insecticides, which have high activity against lepidopteran insects.  Several diamide insecticides have been used to control pests in orchards in China.  To enhance our understanding of the effects of diamides on RyRs, full-length cDNAs were isolated and characterized from the summer fruit tortrix moth, Adoxophyes orana, which is the most severe pest of stone and pome trees worldwide.  In addition, the modulation of AoRyR mRNA expression by diamide insecticides was investigated.  The AoRyR mRNA obtained had an open reading frame (ORF) of 15 402 bp nucleotides encoding 5 113 amino acids, and shared high and low identity with its orthologs in other insects and mammals of 77–92 and 45–47% identity, respectively.  One alternative splice site with two exclusive exons was revealed in AoRyR (a/b).  The usage of exon was more frequent in eggs and larvae than in pupae and adults.  Quantitative real-time reverse transcription PCR (qRT-PCR) showed that AoRyR mRNA was expressed at all developmental stages, especially in eggs, male pupae and male adults.  The expression levels of AoRyR mRNA in the whole body were up-regulated markedly after 3rd instar larvae were treated with chlorantraniliprole at LC10, LC20 and LC50 dosages.  The results could provide the basis for further functional studies of AoRyR and for the development of new chemicals with selective activity against insects. 
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    Cuticular protein gene LmACP8 is involved in wing morphogenesis in the migratory locust, Locusta migratoria
    ZHAO Xiao-ming, YANG Jia-peng, GOU Xin, LIU Wei-min, ZHANG Jian-zhen
    2021, 20 (6): 1596-1606.   DOI: 10.1016/S2095-3119(20)63248-8
    Abstract62)      PDF in ScienceDirect      
    Cuticular proteins (CPs) are major components of the insect cuticle-associated organs such as integument and wings, although the importance of CPs for wing development and function in hemimetabolous insects remains understudied.  In the present study, a wing cuticular protein LmACP8 was identified from Locusta migratoria, which belongs to the RR-2 subfamily of cuticular protein R&R consensus (CPR) chitin-binding proteins.  LmACP8 was mainly expressed in the wing pads and showed high expression levels before ecdysis of third-, fourth-, and fifth-instar nymphs, with its encoded protein located in the procuticle of wing pads and adult wings.  Depletion of LmACP8 by RNA interference markedly reduced the amount of its protein, which consequently caused abnormal wing morphogenesis in the transition from nymph to adult of L. migratoria.  We further demonstrated that the abnormal morphogenesis was caused by severe damage of the endocuticle in the wings.  LmACP8 was suppressed by 20-hydroxyecdysone (20E) in vivo, however, its expression was significantly up-regulated after knocking down the hormone receptor gene LmHR39.  Thus, the LmACP8 that is negatively regulated by the LmHR39-mediated 20E signaling pathway is involved in wing development during the nymph to adult transition.
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    Functional analysis of the orphan genes Tssor-3 and Tssor-4 in male Plutella xylostella
    LI Tian-pu, ZHANG Li-wen, LI Ya-qing, YOU Min-sheng, ZHAO Qian
    2021, 20 (7): 1880-1888.   DOI: 10.1016/S2095-3119(21)63655-9
    Abstract74)      PDF in ScienceDirect      
    Orphan genes are genes with no sequence homologues in other species.  Here, we identified two orphan genes, namely, Tssor-3 and Tssor-4, in Plutella xylostella.  Both genes contained a signal peptide sequence, suggesting their functions as secreted proteins.  Expression pattern analysis based on real-time quantitative PCR (qPCR) showed that both orphan genes were specifically expressed in all male gonads except the testes.  The expression of both the orphan genes peaked at the male adult stage.  Immunofluorescence assays suggested that the two proteins were seminal proteins, indicating their potential roles in male reproductive regulation.  To further explain their functions, we knocked down the expression of these two genes by RNA interference (RNAi).  The results showed that the expression of Tssor-3 and Tssor-4 was significantly downregulated at 24 h after injection compared to that of the controls.  Biological assays showed that the number of laid eggs and the hatching rate of offspring eggs were significantly reduced when the expression of Tssor-3 and Tssor-4 was reduced, suggesting that the two orphan genes played a role in male fertility in P. xylostella.  Our results provide evidence that orphan genes are involved in male reproductive regulation, which is important for male fitness during evolution.
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    Potential influence of carbohydrate and amino acid intake by adults on the population dynamics of Cnaphalocrocis medinalis (Lepidoptera: Crambidae)
    LI Chuan-ming, XU Jian, LIU Qin, HAN Guang-jie, XU Bin, YANG Yi-zhong, LIU Xian-jin
    2021, 20 (7): 1889-1897.   DOI: 10.1016/S2095-3119(20)63419-0
    Abstract66)      PDF in ScienceDirect      
    Cnaphalocrocis medinalis is a key lepidopteran pest of rice.  However, little is known about the nutritional requirements of the adult or the effects of adult-derived nutrients on reproduction.  The aim of the present study was to evaluate the effects of carbohydrates and amino acids on the reproductive and demographic parameters of C.?medinalis.  Different feeding solutions significantly influenced adult survival and reproduction.  All the sources of carbohydrates used in the treatments (fructose, glucose, and sucrose) were sufficient to increase adult longevity and fecundity, and benefited the development of ovaries in the adult stage.  The positive impact of carbohydrates on lifetime fecundity was due to the prolonged oviposition period and the increased daily fecundity.  The intrinsic rate of increase (rm) of C.?medinalis increased from 0.103 in water-fed individuals to approximately 0.138 when adults were fed with solutions containing carbohydrates.  In contrast, amino acid intake by adult insects exhibited no effect on the longevity, fecundity, ovarian development or population growth, even showing an impact of decreasing longevity of females.  As nectar secreted by the flowering plant is generally rich in sugars, the potential effects of nectar on the adults of C.?medinalis and other pests have to be considered during the development of biological control by applying flowering plants as a microhabitat and food source for natural enemies in rice fields.
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    Effects of inhibitors on the protease profiles and degradation of activated Cry toxins in larval midgut juices of Cnaphalocrocis medinalis (Lepidoptera: Pyralidae)
    YANG Ya-jun, XU Hong-xing, WU Zhi-hong, LU Zhong-xian
    2021, 20 (8): 2195-2203.   DOI: 10.1016/S2095-3119(20)63316-0
    Abstract53)      PDF in ScienceDirect      
    Midgut juice plays an important role in food digestion and detoxification in insects.  In order to understand the potential of midgut juice of Cnaphalocrocis medinalis (Guenée) to degrade Bt proteins, the enzymatic activity of midgut juice and its degradation of Bt proteins (Cry2A, Cry1C, Cry1Aa, and Cry1Ac) were evaluated in this study through protease inhibitor treatments.  The activities of total protease in midgut juices were significantly inhibited by phenylmethylsulfonyl fluoride (PMSF), tosyl-L-lysine chloromethyl ketone (TLCK), pepstatin A and leupeptin.  The enzymatic activity of chymotrypsin was significantly inhibited by PMSF, and enzymatic activity of trypsin was significantly inhibited by ethylenediaminetetraacetic acid (EDTA), PMSF, tosyl phenylalanine chloromethyl ketone (TPCK), TLCK and trans-epoxysuccinyl-L-leucylamido-(4-guanidino) butane (E-64).  EDTA could significantly inhibit the degradation of Cry2A by C. medinalis.  EDTA, PMSF, TPCK, and TLCK could inhibit the degradation of Cry1C and Cry1Aa.  EDTA, PMSF, TPCK, TLCK, and E-64 could inhibit the degradation of Cry1Ac.  Our results indicated that some protease inhibitors hindered various enzymatic activities in the larval midgut of C. medinalis, which may reduce the insect’s ability to degrade Bt toxins.  These findings may aid the application of protease inhibitors in the management of this insect pest in the future.
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    Identification and tissue distribution of odorant binding protein genes in Harmonia axyridis (Coleoptera: Coccinellidae)
    QU Cheng, WANG Ran, CHE Wu-nan, LI Feng-qi, ZHAO Hai-peng, WEI Yi-yun, LUO Chen, XUE Ming
    2021, 20 (8): 2204-2213.   DOI: 10.1016/S2095-3119(20)63297-X
    Abstract57)      PDF in ScienceDirect      
    The olfactory system of insects is crucial in modulating behaviors such as host seeking, mating, and oviposition.  Odorant-binding proteins (OBPs) are involved in semiochemical recognition.  OBPs recognize and bind odorants and transport them to odorant receptors located in olfactory neurons.  Harmonia axyridis (Coleoptera: Coccinellidae) is a widely used predacious biological control agent for many agricultural and forestry pests.  This study identified 19 OBPs in H.?axyridis based on the antennal and whole-body transcriptomes of adults and obtained all the full-length open reading frames, including 11 ‘Classic’ OBPs, 7 ‘Minus-C’ OBPs and 1 ‘Plus-C’ OBP.  They encoded 125 to 241 amino acid proteins with molecular weights ranging from 13.75 to 27.75 kDa and isoelectric points ranging from 4.15 to 8.80.  Phylogenetic analyses were used to study the relationships between H.?axyridis OBPs and OBPs from other species of Coleoptera.  Quantitative real-time PCR (qPCR) analysis showed that HaxyOBP2, 3, 5, 8, 10, 12, 13, 14, and 15 were highly expressed in antennae of both adult females and males.  Moreover, HaxyOBP2, 3, 5, 12, and 15 were more abundantly expressed in antennae than other body parts, while HaxyOBP13 and HaxyOBP14 were expressed predominantly, and at similar levels, in the head and antennae.  The other OBP genes were highly expressed in non-olfactory tissues including the thorax, abdomen, legs, and wings.  These results provide valuable information for further study of H.?axyridis olfaction, which may ultimately enhance its use as a biocontrol agent.
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    Stability evaluation of reference genes for real-time quantitative PCR normalization in Spodoptera frugiperda (Lepidoptera: Noctuidae)
    SHU Ben-shui, YU Hai-kuo, DAI Jing-hua, XIE Zi-ge, QIAN Wan-qiang, LIN Jin-tian
    2021, 20 (9): 2471-2482.   DOI: 10.1016/S2095-3119(20)63298-1
    Abstract84)      PDF in ScienceDirect      
    Real-time quantitative PCR (qPCR) is a reliable and widely used technique for analyzing the expression profiles of target genes in different species, and reference genes with stable expressions have been introduced for the normalization of the data.  Therefore, stability evaluation should be considered as the initial step for qPCR experiments.  The fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is a polyphagous pest that consumes many plant species and seriously threatens corn production around the world.  However, no studies thus far have examined the stability of reference genes in this pest.  In this study, the expression profiles of the eight candidate reference genes of Actin, elongation factor 1 alpha (EF1α), elongation factor 2 (EF2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ribosomal protein L3 (RPL3), ribosomal protein L13 (RPL13), alpha-tubulin (α-TUB), and beta-1-tubulin (β-1-TUB) were obtained from S. frugiperda in different samples and the stability was evaluated by ΔCt, BestKeeper, geNorm, NormFinder, and RefFinder methods.  The results of pairwise variation (V) calculated by GeNorm indicated two reference genes could be selected for normalization.  Therefore, the combinations of the most stable reference genes for different experimental conditions of S. frugiperda were shown as follows: EF2 and RPL13 for developmental stages, RPL3 and β-1-TUB for larval tissue samples, EF2 and EF1α for the larval samples treated with different temperatures, RPL3 and EF1α for the larval samples under starvation stress, and RPL13 and EF1α for all the samples.  Our results lay the foundation for the normalization of qPCR analyses in S. frugiperda and could help guarantee the accuracy of subsequent research.
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    Egg tanning improves the efficiency of CRISPR/Cas9-mediated mutant locust production by enhancing defense ability after microinjection
    ZHANG Ting-ting, WEN Ting-mei, YUE Yang, YAN Qiang, DU Er-xia, FAN San-hong, Siegfried ROTH, LI Sheng, ZHANG Jian-zhen, ZHANG Xue-yao, ZHANG Min
    2021, 20 (10): 2716-2726.   DOI: 10.1016/S2095-3119(21)63736-X
    Abstract89)      PDF in ScienceDirect      
    The mutant efficiency and hatching ratio are two key factors that significantly affect the construction of genome-modified mutant insects.  In the construction of CRISPR/Cas9-mediated dsLmRNase2–/–mutant locusts, we found that the tanned eggs which experienced a 20-min contact with the oocyst exhibited a higher success rate compared to fresh newly-laid eggs that were less tanned.  However, the heritable efficiency of the dsLmRNase2 deletion to the next generation G1 progeny was similar between adults derived from the tanned or less tanned engineered eggs.  Further, the similar effective mutant ratios in the normally developed eggs and G0 adults of tanned and less tanned eggs also indicated that tanning did not reduce the absolute mutation efficiency induced by CRISPR/Cas9.  Moreover, we found that the syncytial division period, which was longer than the time for tanning, conferred a window period for microinjection treatment with efficient mutation in both tanned and less tanned eggs.  We further found that tanned eggs exhibited a higher hatching rate due to a reduced infection rate following microinjection.  Both the anti-pressure and ultrastructure analyses indicated that the tanned eggs contained compressed eggshells to withstand increased external pressure.  In summary, tanned eggs possess stronger defense responses and higher efficiency of genome editing, providing an improved model for developing Cas9-mediated gene editing procedures in locusts.
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    Optimization of the sex pheromone-based method for trapping field populations of Phthorimaea operculella (Zeller) in South China
    YAN Jun-jie, MEI Xiang-dong, FENG Jia-wen, LIN Zhi-xu, Stuart REITZ, MENG Rui-xia, GAO Yu-lin
    2021, 20 (10): 2727-2733.   DOI: 10.1016/S2095-3119(20)63320-2
    Abstract79)      PDF in ScienceDirect      
    Despite the identification of the potato tuber moth Phthorimaea operculella (Zeller) sex pheromone, no effective application based on this pheromone has yet been developed and evaluated.  This study investigated the effect of pheromone lures, trap densities, heights of trap deployment, and pheromone doses in Yunnan, China, for the purpose of increasing the control efficiency of P. operculella and improving the application of pheromone technology in the field.  The results showed that lures made of corn oil and red PVC pipes attracted the highest number of moths (11.73±1.90 per trap per day).  Sex pheromone loading of 100 μg was optimal for trapping moths, but higher doses of pheromone inhibited attraction.  The density of traps did not affect capture rates; therefore, the optimum trap density was 30–40 traps ha–1.  The optimum height of trap deployment was not above the height of the plant canopy.  This study provides technical details necessary for the monitoring and control of potato tuber moth using sex pheromones.
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    Changes in organic C stability within soil aggregates under different fertilization patterns in a greenhouse vegetable field
    LUAN Hao-an, YUAN Shuo, GAO Wei, TANG Ji-wei, LI Ruo-nan, ZHANG Huai-zhi, HUANG Shao-wen
    2021, 20 (10): 2758-2771.   DOI: 10.1016/S2095-3119(21)63646-8
    Abstract83)      PDF in ScienceDirect      
    Knowledge of the stability of soil organic C (SOC) is vital for assessing SOC dynamics and cycling in agroecosystems.  Studies have documented the regulatory effect of fertilization on SOC stability in bulk soils. However, how fertilization alters organic C stability at the aggregate scale in agroecosystems remains largely unclear.  This study aimed to appraise the changes of organic C stability within soil aggregates after eight years of fertilization (chemical vs. organic fertilization) in a greenhouse vegetable field in Tianjin, China.  Changes in the stability of organic C in soil aggregates were evaluated by four methods, i.e., the modified Walkley-Black method (chemical method), 13C NMR spectroscopy (spectroscopic method), extracellular enzyme assay (biological method), and thermogravimetric analysis (thermogravimetric method).  The aggregates were isolated and separated by a wet-sieving method into four fractions: large macroaggregates
    (>2 mm), small macroaggregates (0.25–2 mm), microaggregates (0.053–0.25 mm), and silt/clay fractions (<0.053 mm).  The results showed that organic amendments increased the organic C content and reduced the chemical, spectroscopic, thermogravimetric, and biological stability of organic C within soil aggregates relative to chemical fertilization alone.  Within soil aggregates, the content of organic C was the highest in microaggregates and decreased in the order microaggregates>macroaggregates>silt/clay fractions.  Meanwhile, organic C spectroscopic, thermogravimetric, and biological stability were the highest in silt/clay fractions, followed by macroaggregates and microaggregates.  Moreover, the modified Walkley-Black method was not suitable for interpreting organic C stability at the aggregate scale due to the weak correlation between organic C chemical properties and other stability characteristics within the soil aggregates.  These findings provide scientific insights at the aggregate scale into the changes of organic C properties under fertilization in greenhouse vegetable fields in China.
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    The sex peptide receptor in the Asian gypsy moth, Lymantria dispar, is involved in development and stress resistance
    DU Hui, SUN Li-li, LIU Peng, CAO Chuan-wang
    2021, 20 (11): 2976-2985.   DOI: 10.1016/S2095-3119(20)63365-2
    Abstract96)      PDF in ScienceDirect      
    The G protein-coupled receptor (GPCR) regulates downstream genes by binding to a heterotrimeric G protein.  However, the function of sex peptide receptor (SPR) in lepidopteran species is mostly unknown.  Understanding the physiological functions of SPR in insects is essential for exploring new insecticidal targets.  In the present study, the functions of an SPR in Lymantria dispar (Asian gypsy moth; LdSPR) were investigated.  The expression of LdSPR was the highest in the 6th instar larval stage, and there was a large difference in expression between male and female adults.  After LdSPR gene silencing, L.?dispar larvae showed increased sensitivity to high temperature, starvation, and oxidative stress, indicating that LdSPR enhances stress resistance.  These results enrich our knowledge of the function of the insect SPRs, which will lead to a better understanding of other insect GPCR family members and the identification of new targets for the development of environmentally friendly pesticides.
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    Functional identification of C-type lectin in the diamondback moth, Plutella xylostella (L.) innate immunity
    LI Jin-yang, LIN Jun-han, G. Mandela FERNáNDEZ-GRANDON, ZHANG Jia-yu, YOU Min-sheng, XIA Xiao-feng
    2021, 20 (12): 3240-3255.   DOI: 10.1016/S2095-3119(21)63650-X
    Abstract118)      PDF in ScienceDirect      
    C-type lectins (CTLs) are a superfamily of Ca2+-dependent carbohydrate-recognition proteins, and an important pattern recognition receptor (PRR) in insect innate immunity which can mediate humoral and cellular immunity in insects.  In this study, we report a novel dual carbohydrate-recognition domain (CRD) CTL from Plutella xylostella which we designate PxIML.  PxIML is a protein with a 969 bp open reading frame (ORF) encoding 322 amino acids, containing a signal peptide and a dual-CRD with EPN (Glu124-Pro125-Asn126) and QPD (Gln274-Pro275-Asp276) motifs.  The expression of PxIML mRNA in the fat body was significantly higher than in hemocytes and midgut.  The relative expression levels of PxIML in the whole insect and the fat body were significantly inhibited after infection with Bacillus thuringiensis 8010 (Bt8010) at 18 h, while they were significantly upregulated after infection with Serratia marcescens IAE6 or Pichia pastoris.  The recombinant PxIML (rPxIML) protein could bind to the tested pathogen-associated molecular patterns (PAMPs), and the bacteria of Enterobacter sp. IAE5, S. marcescens IAE6, Staphylococcus aureus, Escherichia coli BL21, and Bt8010 in a Ca2+-dependent manner, however, it showed limited binding to the fungus, P. pastoris.  The rPxIML exhibited strong activity in the presence of Ca2+ to agglutinate Bt8010, Enterobacter sp. IAE5 and S. aureus, but it only weakly agglutinated with E. coli BL21, and could not agglutinate with S. marcescens IAE6 or P. pastoris.  Furthermore, the rPxIML could bind to hemocytes, promote the adsorption of hemocytes to beads, and enhance the phenoloxidase (PO) activity and melanization of P. xylostella.  Our results suggest that PxIML plays an important role in pathogen recognition and in mediating subsequent humoral and cellular immunity of P. xylostella.
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