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Fajun Chen - One of the best experts on this subject based on the ideXlab platform.
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molecular evidence for the fitness of Cotton Aphid aphis gossypii in response to elevated co2 from the perspective of feeding behavior analysis
Frontiers in Physiology, 2018Co-Authors: Shoulin Jiang, Megha N Parajulee, Yang Dai, Shuqin Fan, Yanmin Liu, Muhammad Adnan Bodlah, Fajun ChenAbstract:Rising atmospheric carbon dioxide (CO2) concentration is likely to influence insect-plant interactions. Aphid, as a typical phloem-feeding herbivorous insect, has shown consistently more positive responses in fitness to elevated CO2 concentrations than those seen in leaf-chewing insects. But, little is known about the mechanism of this performance. In this study, the foliar soluble constituents of Cotton and the life history of the Cotton Aphid Aphis gossypii and its mean relative growth rate (MRGR) and feeding behavior were measured, as well as the relative transcript levels of target genes related appetite, salivary proteins, molting hormone (MH), and juvenile hormone, to investigate the fitness of A. gossypii in response to elevated CO2 (800 ppm vs. 400 ppm). The results indicated that elevated CO2 significantly stimulated the increase in concentrations of soluble proteins in the leaf and sucrose in seedlings. Significant increases in adult longevity, lifespan, fecundity, and MRGR of A. gossypii were found under elevated CO2 in contrast to ambient CO2. Furthermore, the feeding behavior of A. gossypii was significantly affected by elevated CO2, including significant shortening of the time of stylet penetration to phloem position and significant decrease in the mean frequency of xylem phase. It is presumed that the fitness of A. gossypii can be enhanced, resulting from the increases in nutrient sources and potential increase in the duration of phloem ingestion under elevated CO2 in contrast to ambient CO2. In addition, the qPCR results also demonstrated that the genes related to appetite and salivary proteins were significantly upregulated, whereas, the genes related to MH were significantly downregulated under elevated CO2 in contrast to ambient CO2, this is in accordance with the performance of A. gossypii in response to elevated CO2. In conclusion, rise in atmospheric CO2 concentration can enhance the fitness of A. gossypii by increasing their ingestion of higher quantity and higher quality of host plant tissues and by simultaneously upregulating the transcript expression of the genes related to appetite and salivary proteins, and then this may increase the control risk of A. gossypii under conditions of climate change in the future.
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host selection behavior and physiological mechanisms of the Cotton Aphid aphis gossypii in response to rising atmospheric carbon dioxide levels
Journal of Insect Physiology, 2018Co-Authors: Yang Dai, Megha N Parajulee, Mengfei Wang, Shoulin Jiang, Yifei Zhang, Fajun ChenAbstract:Abstract Rising atmospheric carbon dioxide (CO2) levels can markedly affect the growth, development, reproduction and behavior of herbivorous insects, mainly by changing the primary and secondary metabolites of their host plants. However, little is known about the host-selection behavior and the respective intrinsic mechanism of sap-sucking insects in response to elevated CO2. In this experiment, the host-selection behavior, as well as the physiological mechanism based on the analysis of growth, development and energy substances, and the expression of the olfactory-related genes of the Cotton Aphid, Aphis gossypii, were studied under ambient (407.0 ± 4.3 μl/L) and elevated (810.5 ± 7.2 μl/L) CO2. The results indicated that the Aphids reared under ambient and elevated CO2 did not differ in their level of preference for Cotton seedlings, whatever the CO2 conditions in which the plants developed. However, Aphids reared under elevated CO2 showed a greater ability to respond to the plant volatiles compared to Aphids that developed under ambient CO2 (+23.3%). This suggests that rising atmospheric CO2 enhances the activity of host selection in this Aphid. Compared with ambient CO2, elevated CO2 significantly increased Aphid body weight (+36.7%) and the contents of glycogen (+18.9%), body fat (+14.6%), and amino acids (+16.8%) and increased the expression of odor-binding protein genes, OBP2 (+299.6%) and OBP7 (+47.4%), and chemosensory protein genes, CSP4 (+265.3%) and CSP6 (+50.9%), potentially enhancing the overall life activities and upregulating the olfactory ability of A. gossypii. We speculated that the rising atmospheric CO2 level would likely aggravate the damage caused by A. gossypii due to the higher potential host selection and increased general activity under future climate change.
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feeding behavioral response of Cotton Aphid aphis gossypii to elevated co2 epg test with leaf microstructure and leaf chemistry
Entomologia Experimentalis Et Applicata, 2016Co-Authors: Shoulin Jiang, Megha N Parajulee, Tongjin Liu, Limin Zhang, Fajun ChenAbstract:Effect of elevated CO2 on feeding behavior of the Cotton Aphid, Aphis gossypii (Glover) (Hemiptera: Aphididae), was investigated using electrical penetration graphs (EPG) on Cotton, Gossypium hirsutum L. (Malvaceae). Leaf microstructures and foliar soluble constituents were also measured simultaneously to quantify the impact of foliar changes on leaf nutritional quantity and quality, owing to elevated CO2, on stylet penetration and food-quality plasticity of A. gossypii. Significant increases in fresh body weight, fecundity, and population abundances of A. gossypii were found in elevated CO2 in contrast to ambient CO2. Elevated CO2 influenced the feeding behavior, as evidenced by altered EPG recordings, including the increased non-penetration period (walking and finding the feeding site), E2 8 min (first occurrence of probes with sustained ingestion of >8 min), and decreased E2>8 min recordings. Moreover, leaf microstructures were significantly affected by CO2 levels, with thinner upside epidermis (UPE) and thicker underside epidermis (UDE), sponge tissues (ST), and fence tissues under elevated CO2 compared to that in ambient CO2. Therefore, it is expected that A. gossypii spend more time penetrating the thicker leaf UDE and ST when the host plant is exposed to elevated CO2. Furthermore, elevated CO2 significantly enhanced foliar soluble matter, including soluble sugars (SS), free amino acids and fatty acids (FFA), and total soluble matter (TSM), which was congruent with significant increase or decrease in leaf turgor or osmotic potential. Increased leaf turgor and leaf soluble constituents favored ingestion in A. gossypii, resulting in increases in fresh body weight, fecundity, and population abundances under elevated CO2. These feeding behaviors and resulting population growth parameters are consistent with the significant positive correlations between Aphid fresh body weight and foliar FFA/TSM, between A. gossypii fecundity and foliar SS of Cotton plants, and between the time of E2<8 min recordings and leaf turgor.
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influences of elevated co2 and pest damage on the allocation of plant defense compounds in bt transgenic Cotton and enzymatic activity of Cotton Aphid
Insect Science, 2011Co-Authors: Gang Wu, Fajun Chen, Nengwen Xiao, Feng GeAbstract:Plant allocation to defensive compounds by elevated CO2-grown non- transgenic and transgenic Bt Cotton in response to infestation by Cotton Aphid, Aphis gossypii (Glover) in open-top chambers under elevated CO2 were studied. The results showed that significantly lower foliar nitrogen concentration and Bt toxin protein occurred in transgenic Bt Cotton with and without Cotton Aphid infestation under elevated CO2. However, significantly higher carbon/nitrogen ratio, condensed tannin and gossypol were observed in transgenic Bt Cotton "GK-12" and non-transgenic Bt Cotton 'Simian-3' under elevated CO2. The CO2 level and Cotton variety significantly influenced the foliar nitro- gen, condensed tannin and gossypol concentrations in the plant leaves after feeding by A. gossypii. The interaction between CO2 level × infestation time (24 h, 48 h and 72 h) showed a significant increase in Cotton condensed tannin concentrations, while the interac- tion between CO2 level × Cotton variety significantly decreased the true choline esterase (TChE) concentration in the body of A. gossypi. This study exemplified the complexities of predicting how transgenic and non-transgenic plants will allocate defensive compounds in response to herbivorous insects under differing climatic conditions. Plant defensive compound allocation patterns and Aphid enzyme changes observed in this study appear to be broadly applicable across a range of plant and herbivorous insect interactions as CO2 atmosphere rises.
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transgenic bacillus thuringiensis bt Cotton gossypium hirsutum allomone response to Cotton Aphid aphis gossypii in a closed dynamics co 2 chamber cdcc
Journal of Plant Research, 2007Co-Authors: Fajun Chen, Yucheng SunAbstract:Allocation of allomones of transgenic Bacillus thuringiensis Gossypium hirsutum (Bt Cotton) (cv. GK-12) and non-Bt-transgenic Cotton (cv. Simian-3) grown in elevated CO2 in response to infestation by Cotton Aphid, Aphis gossypii Glover, was studied in a closed-dynamics CO2 chamber. Significant increases in foliar condensed tannin and carbon/nitrogen ratio for GK-12 and Simian-3 were observed in elevated CO2 relative to ambient CO2, as partially supported by the carbon nutrient balance hypothesis, owing to limiting nitrogen and excess carbon in Cotton plants in response to elevated CO2. The CO2 level significantly influenced the foliar nutrients and allomones in the Cotton plants. Aphid infestation significantly affected foliar nitrogen and allomone compounds in the Cotton plants. Allomone allocation patterns in transgenic Bt Cotton infested by A. gossypii may have broader implications across a range of plant and herbivorous insects as CO2 continues to rise.
Xiwu Gao - One of the best experts on this subject based on the ideXlab platform.
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cross resistance and fitness cost analysis of resistance to thiamethoxam in melon and Cotton Aphid hemiptera Aphididae
Journal of Economic Entomology, 2020Co-Authors: Huihui Zhang, Anqi Chen, Tisheng Shan, Wenyang Dong, Xueyan Shi, Xiwu GaoAbstract:The melon/Cotton Aphid, Aphis gossypii Glover, is a notorious pest in many crops. The neonicotinoid insecticide thiamethoxam is widely used for A. gossypii control. To evaluate thiamethoxam resistance risk, a melon/Cotton Aphid strain with an extremely high level of resistance to thiamethoxam (>2,325.6-fold) was established after selection with thiamethoxam for 24 generations. Additionally, the cross-resistance pattern to other neonicotinoids and fitness were analyzed. The cross-resistance results showed the thiamethoxam-resistant strain had extremely high levels of cross-resistance against clothianidin (>311.7-fold) and nitenpyram (299.9-fold), high levels of cross-resistance against dinotefuran (142.3-fold) and acetamiprid (76.6-fold), and low cross-resistance against imidacloprid (9.3-fold). Compared with the life table of susceptible strain, the thiamethoxam-resistant strain had a relative fitness of 0.950, with significant decreases in oviposition days and fecundity and prolonged developmental duration. The molecular mechanism for fitness costs was studied by comparing the mRNA expression levels of juvenile hormone acid O-methyltransferase (JHAMT), juvenile hormone-binding protein (JHBP), juvenile hormone epoxide hydrolase (JHEH), ecdysone receptor (EcR), ultraspiracle protein (USP), and Vitellogenin (Vg) in the susceptible and thiamethoxam-resistant strains. Significant overexpression of JHEH and JHBP and downregulation of EcR and Vg expression were found in the thiamethoxam-resistant strain. These results indicate that A. gossypii has the potential to develop extremely high resistance to thiamethoxam after continuous exposure, with a considerable fitness cost and cross-resistance to other neonicotinoids.
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the overexpression of three cytochrome p450 genes cyp6cy14 cyp6cy22 and cyp6un1 contributed to metabolic resistance to dinotefuran in melon Cotton Aphid aphis gossypii glover
Pesticide Biochemistry and Physiology, 2020Co-Authors: Anqi Chen, Huihui Zhang, Tisheng Shan, Xueyan Shi, Xiwu GaoAbstract:Dinotefuran, the third-generation neonicotinoid, has been applied against melon/Cotton Aphid Aphis gossypii Glover in China. The risk of resistance development, cross-resistance pattern and potential resistance mechanism of dinotefuran in A. gossypii were investigated. A dinotefuran-resistant strain of A. gossypii (DinR) with 74.7-fold resistance was established by continuous selection using dinotefuran. The DinR strain showed a medium level of cross resistance to thiamethoxam (15.2-fold), but no cross resistance to imidacloprid. The synergism assay indicated that piperonyl butoxide and triphenyl phosphate showed synergistic effects on dinotefuran toxicity to the DinR strain with a synergistic ratio of 8.3 and 2.5, respectively, while diethyl maleate showed no synergistic effect. The activities of cytochrome P450 monooxygenase and carboxylesterase were significantly higher in DinR strain than in susceptible strain (SS). Moreover, the gene expression results showed that CYP6CY14, CYP6CY22 and CYP6UN1 were significantly overexpressed in DinR strain compared with SS strain. The expression of CYP6CY14 was 5.8-fold higher in DinR strain than in SS strain. Additionally, the transcription of CYP6CY14, CYP6CY22 and CYP6UN1 in A. gossypii showed dose- and time-dependent responses to dinotefuran exposure. Furthermore, knockdown of CYP6CY14, CYP6CY22 and CYP6UN1 via RNA interference (RNAi) significantly increased mortality of A. gossypii, when A. gossypii was treated with dinotefuran. These results demonstrated the overexpression of CYP6CY14, CYP6CY22 and CYP6UN1 contributed to dinotefuran resistance in A. gossypii.
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toxicity and sublethal effects of two plant allelochemicals on the demographical traits of Cotton Aphid aphis gossypii glover hemiptera Aphididae
PLOS ONE, 2019Co-Authors: Qiuling Tang, Pingzhuo Liang, Jin Xia, Baizhong Zhang, Xiwu GaoAbstract:Plant allelochemicals are a group of secondary metabolites produced by plants to defend against herbivore. The mortality of two plant allelochemicals (tannic acid and gossypol) on the Cotton Aphid, Aphis gossypii Glover (Hemiptera: Aphididae), were investigated using feeding assays and the sublethal effects were evaluated using the age-stage, two-sex life table approach. Tannic acid and gossypol have deleterious effects on A. gossypii, and as the concentrations increased, the mortality of Cotton Aphid increased. The life history traits of A. gossypii including the developmental duration of each nymph stage, the longevity, oviposition days, total preadult survival rate and adult pre-oviposition period were not significantly affected by sublethal concentration of tannic acid (20 mg/L) and gossypol (50 mg/L), while the population parameters (r, λ and R0) were significantly affected by these two plant allelochemicals. Furthermore, tannic acid can increase the pre-adult duration time and TPOP but reduce the fecundity of A. gossypii significantly compared to the control and gossypol treatment groups. These results are helpful for comprehensively understanding the effects of plant allelochemicals on A. gossypii.
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Transgenic Bt Cotton Does Not Disrupt the Top-Down Forces Regulating the Cotton Aphid in Central China
PLoS ONE, 2016Co-Authors: Yong-sheng Yao, Peng Han, Chang-ying Niu, Jinjie Cui, Xiwu Gao, Yong-cheng Dong, Nicolas DesneuxAbstract:Top-down force is referred to arthropod pest management delivered by the organisms from higher trophic levels. In the context of prevalent adoption of transgenic Bt crops that produce insecticidal Cry proteins derived from Bacillus thuringiensis (Bt), it still remains elusive whether the top-down forces are affected by the insect-resistant traits that introduced into the Bt crops. We explored how Bt Cotton affect the strength of top-down forces via arthropod natural enemies in regulating a non-target pest species, the Cotton Aphid Aphis gossypii Glover, using a comparative approach (i.e. Bt Cotton vs. conventional Cotton) under field conditions. To determine top-down forces, we manipulated predation/parasitism exposure of the Aphid to their natural enemies using exclusion cages. We found that the Aphid population growth was strongly suppressed by the dominant natural enemies including Coccinellids, spiders and Aphidiines parasitoids. Coccinellids, spiders and the assemblage of other arthropod natural enemies (mainly lacewings and Hemipteran bugs) are similarly abundant in both plots, but with the parasitoid mummies less abundant in Bt Cotton plots compared to the conventional Cotton plots. However, the lower abundance of parasitoids in Bt Cotton plots alone did not translate into differential top-down control on A. gossypii populations compared to conventional ones. Overall, the top-down forces were equally strong in both plots. We conclude that transgenic Bt Cotton does not disrupt the top-down forces regulating the Cotton Aphid in central China.
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carboxylesterase activity cdna sequence and gene expression in malathion susceptible and resistant strains of the Cotton Aphid aphis gossypii
Comparative Biochemistry and Physiology B, 2009Co-Authors: Yiou Pan, Huilin Guo, Xiwu GaoAbstract:Levels of insecticide resistance, carboxylesterase activity, carboxylesterase expression, and the cDNA sequence of carboxylesterase gene were investigated in malathion resistant and susceptible strains of Cotton Aphids, Aphis gossypii (Glover). The resistant strain (MRR) exhibited 80.6-fold resistance to malathion compared to the susceptible strain (MSS) in Cotton Aphids. Five substrates, alpha-naphthyl acetate (alpha-NA), beta-naphthyl acetate (beta-NA), alpha-naphthyl propionate (alpha-NPr), alpha-naphthyl butyrate (alpha-NB), alpha-naphthyl caprylate (alpha-NC) and S-methyl thiobutyrate (S-MTB) were used to determine carboxylesterase activity in MRR and MSS strains of Cotton Aphids. Carboxylesterase activity was significantly higher in MRR strain than in MSS strain, 3.7-fold for alpha-NA, 3.0-fold for beta-NA, 2.0-fold for alpha-NPr, 2.9-fold for alpha-NB and 1.6-fold for alpha-NC, While for S-MTB, there was nearly no difference between the two strains. Two site mutations (K14Q and N354D) with high frequency were also found by sequence analysis in the MRR strain, compared with the MSS strain. The levels of gene expression for carboxylesterase of both MRR and MSS strains were determined by real-time quantitative PCRs. Compared with the MSS strain, the relative transcription levels and gene copy numbers of the carboxylesterase were 1.99- and 4.42-fold in the MRR strain, respectively. These results indicated that the increased expression of the carboxylesterase resulted from the increased transcription levels of carboxylesterase mRNA and gene copy numbers and combined with the site mutants might play role in Cotton Aphid resistance to malathion.
Nicolas Desneux - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the natural enemy community attacking Cotton Aphid in the bt Cotton ecosystem in northern china
Scientific Reports, 2016Co-Authors: Abid Ali, Nicolas Desneux, Bing LiuAbstract:Planting Bt Cotton in China since 1997 has led to important changes in the natural enemy communities occurring in Cotton, however their specific effect on suppressing the Cotton Aphids (being notorious in conventional Cotton ecosystem) has not been fully documented yet. We observed strong evidence for top-down control of the Aphid population, e.g. the control efficiency of natural enemies on Cotton Aphid increased significantly in open field cages compared to exclusion cages, accounted for 60.2, 87.2 and 76.7% in 2011, 2012 and 2013 season, respectively. The Cotton Aphid populations peaked in early June to late July (early and middle growth stages) in open field Cotton survey from 2011 to 2013. The population densities of Cotton Aphids and natural enemies were highest on middle growth stage while lowest densities were recorded on late stage for Aphids and on early plant stage for natural enemies. Aphid parasitoids (Trioxys spp., Aphidius gifuensis), coccinellids and spiders were key natural enemies of Cotton Aphid. Briefly, natural enemies can suppress Aphid population increase from early to middle plant growth stages by providing biocontrol services in Chinese Bt Cotton.
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Transgenic Bt Cotton Does Not Disrupt the Top-Down Forces Regulating the Cotton Aphid in Central China
PLoS ONE, 2016Co-Authors: Yong-sheng Yao, Peng Han, Chang-ying Niu, Jinjie Cui, Xiwu Gao, Yong-cheng Dong, Nicolas DesneuxAbstract:Top-down force is referred to arthropod pest management delivered by the organisms from higher trophic levels. In the context of prevalent adoption of transgenic Bt crops that produce insecticidal Cry proteins derived from Bacillus thuringiensis (Bt), it still remains elusive whether the top-down forces are affected by the insect-resistant traits that introduced into the Bt crops. We explored how Bt Cotton affect the strength of top-down forces via arthropod natural enemies in regulating a non-target pest species, the Cotton Aphid Aphis gossypii Glover, using a comparative approach (i.e. Bt Cotton vs. conventional Cotton) under field conditions. To determine top-down forces, we manipulated predation/parasitism exposure of the Aphid to their natural enemies using exclusion cages. We found that the Aphid population growth was strongly suppressed by the dominant natural enemies including Coccinellids, spiders and Aphidiines parasitoids. Coccinellids, spiders and the assemblage of other arthropod natural enemies (mainly lacewings and Hemipteran bugs) are similarly abundant in both plots, but with the parasitoid mummies less abundant in Bt Cotton plots compared to the conventional Cotton plots. However, the lower abundance of parasitoids in Bt Cotton plots alone did not translate into differential top-down control on A. gossypii populations compared to conventional ones. Overall, the top-down forces were equally strong in both plots. We conclude that transgenic Bt Cotton does not disrupt the top-down forces regulating the Cotton Aphid in central China.
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Identification of top-down forces regulating Cotton Aphid population growth in transgenic Bt Cotton in central China
PLoS ONE, 2014Co-Authors: Peng Han, Chang-ying Niu, Nicolas DesneuxAbstract:The Cotton Aphid Aphis gossypii Glover is the main Aphid pest in Cotton fields in the Yangtze River Valley Cotton-planting Zone (YRZ) in central China. Various natural enemies may attack the Cotton Aphid in Bt Cotton fields but no studies have identified potential specific top-down forces that could help manage this pest in the YRZ in China. In order to identify possibilities for managing the Cotton Aphid, we monitored Cotton Aphid population dynamics and identified the effect of natural enemies on Cotton Aphid population growth using various exclusion cages in transgenic Cry1Ac (Bt)+CpTI (Cowpea trypsin inhibitor) Cotton field in 2011. The Aphid population growth in the open field (control) was significantly lower than those protected or restricted from exposure to natural enemies in the various exclusion cage types tested. The ladybird predator Propylaea japonica Thunberg represented 65% of Coccinellidae predators, and other predators consisted mainly of syrphids (2.1%) and spiders (1.5%). The Aphid parasitoids Aphidiines represented 76.7% of the total count of the natural enemy guild (mainly Lysiphlebia japonica Ashmead and Binodoxys indicus Subba Rao & Sharma). Our results showed that P. japonica can effectively delay the establishment and subsequent population growth of Aphids during the Cotton growing season. Aphidiines could also reduce Aphid density although their impact may be shadowed by the presence of coccinellids in the open field (likely both owing to resource competition and intraguild predation). The implications of these results are discussed in a framework of the compatibility of transgenic crops and top-down forces exerted by natural enemy guild
Megha N Parajulee - One of the best experts on this subject based on the ideXlab platform.
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molecular evidence for the fitness of Cotton Aphid aphis gossypii in response to elevated co2 from the perspective of feeding behavior analysis
Frontiers in Physiology, 2018Co-Authors: Shoulin Jiang, Megha N Parajulee, Yang Dai, Shuqin Fan, Yanmin Liu, Muhammad Adnan Bodlah, Fajun ChenAbstract:Rising atmospheric carbon dioxide (CO2) concentration is likely to influence insect-plant interactions. Aphid, as a typical phloem-feeding herbivorous insect, has shown consistently more positive responses in fitness to elevated CO2 concentrations than those seen in leaf-chewing insects. But, little is known about the mechanism of this performance. In this study, the foliar soluble constituents of Cotton and the life history of the Cotton Aphid Aphis gossypii and its mean relative growth rate (MRGR) and feeding behavior were measured, as well as the relative transcript levels of target genes related appetite, salivary proteins, molting hormone (MH), and juvenile hormone, to investigate the fitness of A. gossypii in response to elevated CO2 (800 ppm vs. 400 ppm). The results indicated that elevated CO2 significantly stimulated the increase in concentrations of soluble proteins in the leaf and sucrose in seedlings. Significant increases in adult longevity, lifespan, fecundity, and MRGR of A. gossypii were found under elevated CO2 in contrast to ambient CO2. Furthermore, the feeding behavior of A. gossypii was significantly affected by elevated CO2, including significant shortening of the time of stylet penetration to phloem position and significant decrease in the mean frequency of xylem phase. It is presumed that the fitness of A. gossypii can be enhanced, resulting from the increases in nutrient sources and potential increase in the duration of phloem ingestion under elevated CO2 in contrast to ambient CO2. In addition, the qPCR results also demonstrated that the genes related to appetite and salivary proteins were significantly upregulated, whereas, the genes related to MH were significantly downregulated under elevated CO2 in contrast to ambient CO2, this is in accordance with the performance of A. gossypii in response to elevated CO2. In conclusion, rise in atmospheric CO2 concentration can enhance the fitness of A. gossypii by increasing their ingestion of higher quantity and higher quality of host plant tissues and by simultaneously upregulating the transcript expression of the genes related to appetite and salivary proteins, and then this may increase the control risk of A. gossypii under conditions of climate change in the future.
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host selection behavior and physiological mechanisms of the Cotton Aphid aphis gossypii in response to rising atmospheric carbon dioxide levels
Journal of Insect Physiology, 2018Co-Authors: Yang Dai, Megha N Parajulee, Mengfei Wang, Shoulin Jiang, Yifei Zhang, Fajun ChenAbstract:Abstract Rising atmospheric carbon dioxide (CO2) levels can markedly affect the growth, development, reproduction and behavior of herbivorous insects, mainly by changing the primary and secondary metabolites of their host plants. However, little is known about the host-selection behavior and the respective intrinsic mechanism of sap-sucking insects in response to elevated CO2. In this experiment, the host-selection behavior, as well as the physiological mechanism based on the analysis of growth, development and energy substances, and the expression of the olfactory-related genes of the Cotton Aphid, Aphis gossypii, were studied under ambient (407.0 ± 4.3 μl/L) and elevated (810.5 ± 7.2 μl/L) CO2. The results indicated that the Aphids reared under ambient and elevated CO2 did not differ in their level of preference for Cotton seedlings, whatever the CO2 conditions in which the plants developed. However, Aphids reared under elevated CO2 showed a greater ability to respond to the plant volatiles compared to Aphids that developed under ambient CO2 (+23.3%). This suggests that rising atmospheric CO2 enhances the activity of host selection in this Aphid. Compared with ambient CO2, elevated CO2 significantly increased Aphid body weight (+36.7%) and the contents of glycogen (+18.9%), body fat (+14.6%), and amino acids (+16.8%) and increased the expression of odor-binding protein genes, OBP2 (+299.6%) and OBP7 (+47.4%), and chemosensory protein genes, CSP4 (+265.3%) and CSP6 (+50.9%), potentially enhancing the overall life activities and upregulating the olfactory ability of A. gossypii. We speculated that the rising atmospheric CO2 level would likely aggravate the damage caused by A. gossypii due to the higher potential host selection and increased general activity under future climate change.
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feeding behavioral response of Cotton Aphid aphis gossypii to elevated co2 epg test with leaf microstructure and leaf chemistry
Entomologia Experimentalis Et Applicata, 2016Co-Authors: Shoulin Jiang, Megha N Parajulee, Tongjin Liu, Limin Zhang, Fajun ChenAbstract:Effect of elevated CO2 on feeding behavior of the Cotton Aphid, Aphis gossypii (Glover) (Hemiptera: Aphididae), was investigated using electrical penetration graphs (EPG) on Cotton, Gossypium hirsutum L. (Malvaceae). Leaf microstructures and foliar soluble constituents were also measured simultaneously to quantify the impact of foliar changes on leaf nutritional quantity and quality, owing to elevated CO2, on stylet penetration and food-quality plasticity of A. gossypii. Significant increases in fresh body weight, fecundity, and population abundances of A. gossypii were found in elevated CO2 in contrast to ambient CO2. Elevated CO2 influenced the feeding behavior, as evidenced by altered EPG recordings, including the increased non-penetration period (walking and finding the feeding site), E2 8 min (first occurrence of probes with sustained ingestion of >8 min), and decreased E2>8 min recordings. Moreover, leaf microstructures were significantly affected by CO2 levels, with thinner upside epidermis (UPE) and thicker underside epidermis (UDE), sponge tissues (ST), and fence tissues under elevated CO2 compared to that in ambient CO2. Therefore, it is expected that A. gossypii spend more time penetrating the thicker leaf UDE and ST when the host plant is exposed to elevated CO2. Furthermore, elevated CO2 significantly enhanced foliar soluble matter, including soluble sugars (SS), free amino acids and fatty acids (FFA), and total soluble matter (TSM), which was congruent with significant increase or decrease in leaf turgor or osmotic potential. Increased leaf turgor and leaf soluble constituents favored ingestion in A. gossypii, resulting in increases in fresh body weight, fecundity, and population abundances under elevated CO2. These feeding behaviors and resulting population growth parameters are consistent with the significant positive correlations between Aphid fresh body weight and foliar FFA/TSM, between A. gossypii fecundity and foliar SS of Cotton plants, and between the time of E2<8 min recordings and leaf turgor.
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potential Cotton Aphid aphis gossypii population suppression by arthropod predators in upland Cotton
Insect Science, 2013Co-Authors: Ram B Shrestha, Megha N ParajuleeAbstract:The Cotton Aphid, Aphis gossypii Glover, predation rate of convergent lady beetle, Hippodamia convergens Guerin-Meneville, was determined by assigning a single predator randomly to each of four prey density treatments in the laboratory. Prey densities included 25, 50, 100, and 200 Aphids per Petri dish arena. Predation response was recorded at 1, 4, 8, 16, 24, and 48 h after assigning predators to their prey treatments. Rate of consumption increased through time, with all 25 Aphids consumed during the first 4 h of the experiment. At the highest density, adult lady beetle consumed on average 49, 99, 131, 163, 183, and 200 Aphids within 1, 4, 8, 16, 24 and 48 h, respectively. Predators showed a curvilinear feeding response in relation to total available time, indicating that convergent lady beetles have the potential to suppress larger populations of Aphids through continuous feeding by regulating their predation efficiency during feeding. The analysis of age-specific mortality in absence of prey revealed that lady beetles could survive for an extended period of time (more than 2 weeks) without prey. The ability of a predator to survive without prey delays or prevents the rebound of pest populations that is a significant factor in natural biological control. A two-year field sampling of 10 Cotton arthropod predator species showed that spiders (27%) were the most dominant foliage dwelling predators in the Texas High Plains Cotton followed by convergent lady beetles (23.5%), hooded beetles (13.5%), minute pirate bugs (11%), green lacewings (9.5%), bigeyed bugs (7.5%), scymnus beetles (3%), soft-winged flower beetles (2%), damsel bugs (1.5%), and assassin bugs (1.5%). A field cage study showed that one H. convergens adult per plant released at prey density of one Aphid per leaf kept the Aphid population below economic threshold for the entire growing season.
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influence of constant temperatures on life history parameters of the Cotton Aphid aphis gossypii infesting Cotton
Environmental Entomology, 2007Co-Authors: Megha N ParajuleeAbstract:Laboratory clip-cage studies were conducted to quantify the temperature-dependent development, survivorship, and reproduction and to generate life history characteristics and population growth parameters of the Cotton Aphid, Aphis gossypii Glover, on phenologically standardized greenhouse-grown Cottons at 10, 15, 20, 25, 30, and 35°C. The developmental thresholds were estimated to be 6.3, 6.7, 5.9, 5.9, and 6.3°C for first to fourth instars and for total nymphal development, respectively. The maximum rate of development were estimated to occur at 32.2, 30.8, 30.4, 30.0, and 30.2°C for first to fourth instars and for total nymphal development, respectively. Increased temperature resulted in more rapid decline in survivorship, which was particularly sharp at 35°C, dropping from 94 to 17% in 5 d. Number of days elapsed until first deposition of progeny increased progressively and sharply at temperatures 10 (26 d) to 15 (15 d) to 20°C (8 d) and stabilized at 5 d for 25, 30, and 35°C. Average lifetime fecundity of females rose from a low of 9.76 progeny at 10°C to a peak of 58.9 progeny at 30°C and declined sharply to 17.3 at 35°C. Finite rate of population growth was highest at 25°C and lowest at 10°C. Although stage-specific developmental maxima occurred between 30 and 32°C, a nonlinear regression model estimated 28.6°C to be the optimum temperature for overall Cotton Aphid development, reproduction, and population increase.
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development of a stage structured process based predator prey model to analyse biological control of Cotton Aphid aphis gossypii by the sevenspot ladybeetle coccinella septempunctata in Cotton
Ecological Complexity, 2018Co-Authors: J Y Xia, Jing Wang, J J Cui, P A Leffelaar, R Rabbinge, W Van Der WerfAbstract:Agricultural system diversification is well known to affect the population dynamics of crop pests, but predator–prey dynamics in crop systems are difficult to analyse due to interactions between multiple life stages of predator and prey, the modulating effect of temperature, the actions of additional predators, and the open nature of the system, with immigration and emigration of both predators and prey. To better understand and characterize the predator–prey system dynamics under field conditions, we developed a detailed process-based simulation model for the stage structured population interaction between Cotton Aphid, Aphis gossypii, and its main natural enemy, the sevenspot ladybeetle Coccinella septempunctata. The model includes interactions between all insects stages as affected by temperature and host growth, and was parameterized based on detailed data collection in the laboratory and the field. The model was tested with independent data. Simulations show that the initial predator–prey ratio, as affected by immigration rates of the Aphid and the predators into the crop, is the key factor for biological control. The model is a useful tool for scenario assessments on the effects of crop diversification on pest-natural enemy dynamics.
