Agronomy

Research

14 pages, 1268 KiB

Open AccessArticle

The Chickpea Pod Borer, Helicoverpa armigera (Hübner): Yield Loss Estimation and Biorational Insecticide Assessment in Morocco

by Karim El Fakhouri, Rachid Boulamtat, Abdelhadi Sabraoui and Mustapha El Bouhssini

Agronomy 2022, 12(12), 3017; https://doi.org/10.3390/agronomy12123017 - 29 Nov 2022

Cited by 6 | Viewed by 5195

Abstract

Helicoverpa armigera (Hübner) is considered one of the most destructive insect pests of chickpea crops in Morocco; however, the extent of the yield loss it causes in Morocco is unknown. This study assessed the yield losses and pod damage caused by the chickpea [...] Read more.

Helicoverpa armigera (Hübner) is considered one of the most destructive insect pests of chickpea crops in Morocco; however, the extent of the yield loss it causes in Morocco is unknown. This study assessed the yield losses and pod damage caused by the chickpea pod borer H. armigera on four improved Kabuli varieties with insecticide treatment at two different locations. The second part of this study investigated the contact and systemic toxicity of different biological and selective insecticides in the control of the larvae of H. armigera under controlled laboratory and field conditions. The results demonstrated that the yield losses due to H. armigera infestation were in the range of 14.3–31.2%. Chickpea pod borer infestation resulted in losses in the total seed weight for all the chickpea varieties, with the highest yield losses for Zahor (F84-145C) being 31.18% at Allal Tazi followed by Farihane (F84-79C) with 27.38% at the Marchouch station. Emamectin benzoate at 250 g/ha showed a high level of larvicidal and systemic activity, with 100% mortality 24 h after application. Indoxacarb at 25 mL/100 L water, recorded 100% and 92% larval mortality in larvicidal and systemic activity, 48 h after application, respectively. The bioinsecticide spinosad in 30 mL/100 L water resulted in 88% and 92% larval mortality in contact and systemic activity, 48 h after application, respectively. Under field conditions, the two insecticides emamectin benzoate and indoxacarb were found to be highly effective in reducing the H. armigera larval population and pod damage after two sprays. Both insecticide treatments significantly increased grain yields compared with the untreated plots, with 25.8% and 24.5%, respectively. These findings showed that two applications of the selective chemical insecticides emamectin benzoate or indoxacarb with a week interval starting from the pod setting could be incorporated into the management strategies for the control of H. armigera. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

16 pages, 904 KiB

Open AccessArticle

Toxicity and Sublethal Effects of Fluxametamide on the Key Biological Parameters and Life History Traits of Diamondback Moth Plutella xylostella (L.)

by Amit Gope, Gautam Chakraborty, Shanowly Mondal Ghosh, Sayan Sau, Krishnendu Mondal, Abhisek Biswas, Sukamal Sarkar, Pijush Kanti Sarkar and Debashis Roy

Agronomy 2022, 12(7), 1656; https://doi.org/10.3390/agronomy12071656 - 12 Jul 2022

Cited by 10 | Viewed by 3985

Abstract

Fluxametamide, a novel isoxazoline insecticide, is newly registered for the control of various lepidopteran, coleopteran and thysanopteran insect pests on lethal and sublethal levels. In the present study, the toxicity and sublethal effects of fluxametamide on diamondback moth Plutella xylostella (L.), an invasive [...] Read more.

Fluxametamide, a novel isoxazoline insecticide, is newly registered for the control of various lepidopteran, coleopteran and thysanopteran insect pests on lethal and sublethal levels. In the present study, the toxicity and sublethal effects of fluxametamide on diamondback moth Plutella xylostella (L.), an invasive lepidopteran foliage feeder of cruciferous vegetables, were assessed to explore its bio-ecological impact on pest populations. The toxicity of fluxametamide to the third instar larvae of P. xylostella was 0.18 mg L⁻¹ (LC₅₀) at 72 h bioassay. After treatment with LC₁₀ and LC₃₀ concentrations of fluxametamide, the fourth instar larval duration, the rate of deformed pupa and adults, and the adult pre-oviposition period were significantly increased, whereas the pupation rate and pupal weight were significantly decreased in the F₀ generation. In the F₁ generation, sublethal effects of fluxametamide were indicated by a reduced fecundity, rate of pupation and adult emergence, pupal weight, and adult longevity, however a significant increase in eggs and total larval duration, deformed adults rate, and total longevity and pre-oviposition period was observed in the offspring. The intrinsic rate of increase (r), finite rate of increase (λ) and net reproductive rate (R₀) of sublethal treatments were significantly lower than the control. The relative fitness of F₁ was 0.68 and 0.64 in LC₁₀ and LC₃₀ treatments, respectively. The LC₃₀ fluxametamide treatment exhibited increased glutathione S-transferase activities (elevated 1.433-fold) in P. xylostella. Our results suggest that in addition to its high lethal toxicity, the sublethal concentrations of fluxametamide might suppress the reproduction, development and survival of the P. xylostella population and its progeny, which can help to optimize integrated pest management program. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

11 pages, 481 KiB

Open AccessArticle

Sublethal Effects of Three Insecticides on Development and Reproduction of Spodoptera frugiperda (Lepidoptera: Noctuidae)

by Hui-Ming Wu, Hang-Li Feng, Guo-Di Wang, Li-Li Zhang, Lovemore Zulu, Ya-Hui Liu, Yong-Li Zheng and Qiong Rao

Agronomy 2022, 12(6), 1334; https://doi.org/10.3390/agronomy12061334 - 31 May 2022

Cited by 14 | Viewed by 3061

Abstract

Spodoptera frugiperda is a serious invasive pest, which has attracted attention globally in recent years. Research on the sublethal effects of common insecticides on S. frugiperda is important for its comprehensive management in the field. In this paper, the sublethal effects have been [...] Read more.

Spodoptera frugiperda is a serious invasive pest, which has attracted attention globally in recent years. Research on the sublethal effects of common insecticides on S. frugiperda is important for its comprehensive management in the field. In this paper, the sublethal effects have been studied for S. frugiperda exposed to the LC₃₀ concentration of three insecticides, chlorantraniliprole, dinotefuran, and beta-cypermethrin. The results showed that the pupation rates of the treatment groups were significantly lower than that of control group, but there were no significant differences in the eclosion rate. Chlorantraniliprole and beta-cypermethrin significantly inhibited fecundity of the F₀ and F₁ generations, and the number of eggs laid per female decreased by 67.4% and 43.1%, respectively, and that of the F₁ generation decreased by 28.0% and 21.7%, respectively. The intrinsic growth rate (r_m), net growth rate (R₀), and weekly growth rate (λ) of the F₀ generation in the chlorantraniliprole and beta-cypermethrin treatment groups were significantly lower than those in the control group. Additionally, dinotefuran had a certain role in promoting oviposition in the F₀ and F₁ generations, which may stimulate the growth of offspring population and cause the resurgence of pests. The results provide a reference for the effective implementation of the IPM plan in the field to control S. frugiperda. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

18 pages, 2688 KiB

Open AccessArticle

Seed Coating with Triflumezopyrim Induces the Rice Plant’s Defense and Inhibits the Brown Planthopper’s Feeding Behavior

by Chanyuan Xi, Sheraz Ahmad, Julong Yu, Jieyu Zhang, Yu Chen, Guo Zhang, Haowen Zhu, Linquan Ge, Xiangyang Yu and Zhaolin Shu

Agronomy 2022, 12(5), 1202; https://doi.org/10.3390/agronomy12051202 - 17 May 2022

Cited by 3 | Viewed by 2442

Abstract

Triflumezopyrim (TFM), a novel mesoionic insecticide, has been effective in controlling sucking insect pests such as the brown planthopper (BPH). However, the mechanism of TFM as a seed coating agent in paddy fields remains unclear. Here, we investigate the seed germination rates (>80%) [...] Read more.

Triflumezopyrim (TFM), a novel mesoionic insecticide, has been effective in controlling sucking insect pests such as the brown planthopper (BPH). However, the mechanism of TFM as a seed coating agent in paddy fields remains unclear. Here, we investigate the seed germination rates (>80%) and seedling emergence rates (>85%) of rice treated with TFM at 0, 22.5, 45.0, 67.5, and 90.0 g a.i. ha⁻¹ with no significant effect on germination rates. In addition, the low TFM residue concentration (0.04 mg. kg⁻¹) is maintained in the rice stem. Meanwhile, the TFM seeds’ treatments lead to increased oxalic acid, flavonoids, total phenol, callose contents, and elevated C/N ratio in rice plants at 60 and 90 days after sowing (DAS). The electrical penetration graph (EPG) results indicate that TFM as a seed coating treatment prolongs the non-probing period and inhibits phloem sap ingestion at 90 DAS. Furthermore, the mechanically transplanted rice treated with TFM provides long-term prevention against the BPH infestation. This study demonstrates that seeds treated with TFM play a vital role in controlling the BPH population up to >90%. These results provide a novel valuable control strategy for BPH in the rice fields. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

14 pages, 2693 KiB

Open AccessArticle

Volatilization of Dicamba Diglycolamine Salt in Combination with Glyphosate Formulations and Volatility Reducers in Brazil

by Caio Antonio Carbonari, Renato Nunes Costa, Bruno Flaibam Giovanelli, Natalia Cunha Bevilaqua, Matheus Palhano, Henrique Barbosa, Ramiro Fernando Lopez Ovejero and Edivaldo Domingues Velini

Agronomy 2022, 12(5), 1001; https://doi.org/10.3390/agronomy12051001 - 22 Apr 2022

Cited by 8 | Viewed by 2599

Abstract

Dicamba can be included in weed management programs for Brazilian agricultural crops, such as Conyza spp. and Amaranthus spp., and it is essential to implement good management practices that include salts with low volatility levels and appropriate associations to maintain volatility at acceptable [...] Read more.

Dicamba can be included in weed management programs for Brazilian agricultural crops, such as Conyza spp. and Amaranthus spp., and it is essential to implement good management practices that include salts with low volatility levels and appropriate associations to maintain volatility at acceptable levels. The objective of this study was to evaluate the volatilization of dicamba diglycolamine (DGA) salt associated with different glyphosate salts and volatility reducers. Laboratory and field studies were conducted with the application of DGA alone and in mixtures with three glyphosate formulations (potassium salt, ammonium salt, and di-ammonium salt) with and without a volatility reducer. Under laboratory conditions, the sprayed targets (corn straw) were sent to a vapor collection system for subsequent determination of the amount of volatilized dicamba. In the field, the treatments were applied in a tray containing clay soil, and then, these trays were arranged in soybean rows for 48 h under plastic tunnels. The plant injury and the concentrations of the dicamba in the soybean plants at different distances from the tray were determined. The methodologies used in this study were adequate for understanding the volatility of DGA. The volatility of the dicamba DGA salt used was reduced and was managed through the use of volatility reducers and the correct formulation of glyphosate in the mixture. The VR was efficient in reducing the volatility for dicamba alone and DGA in combination with all glyphosate salts. The combination of dicamba DGA salt with glyphosate potassium salt and a volatility reducer was the mixture with the lowest volatility and is the most suitable combination to recommend to farmers. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

13 pages, 1418 KiB

Open AccessArticle

Insecticidal Activity of Aqueous Extracts of Plant Origin on Mahanarva spectabilis (Distant, 1909) (Hemiptera: Cercopidae)

by Vinícius Ferraz Nascimento, Alexander Machado Auad, Tiago Teixeira de Resende, Amanda Jdenaina Mendoza Visconde and Marcelle Leandro Dias

Agronomy 2022, 12(4), 947; https://doi.org/10.3390/agronomy12040947 - 15 Apr 2022

Cited by 4 | Viewed by 3641

Abstract

The spittlebug Mahanarva spectabilis (Distant, 1909) is considered the main and most limiting pest of elephant grass (Pennisetum purpureum Schum.), and has caused economic losses to Brazilian farmers. In this study, we evaluated the insecticidal effects of aqueous extracts of garlic, rue, [...] Read more.

The spittlebug Mahanarva spectabilis (Distant, 1909) is considered the main and most limiting pest of elephant grass (Pennisetum purpureum Schum.), and has caused economic losses to Brazilian farmers. In this study, we evaluated the insecticidal effects of aqueous extracts of garlic, rue, cinnamon, lemongrass, clove, star anise, eucalyptus, tobacco, and thyme on M. spectabilis nymphs. The results indicated that the tobacco extract was the most effective among all extracts, as it reached a mortality of 76%. The next most effective was star anise extract and cinnamon extract was the least effective. In the second stage of tests, we evaluated the insecticidal potential of five concentrations of tobacco extract. The values of LD50 and LD90 calculated for aqueous tobacco extract were, respectively, 11.5% and 33.3% 24 h after application, and 9.2% and 29.5% 48 h after application. We also evaluated different methods of extraction, through comparative tests, and the methods of infusion and decoction proved to be equivalent to those of the method of extraction by ultrasound. We conclude that among the nine aqueous plant extracts tested, tobacco extract was the only one recommended against M. spectabilis, as it showed insecticidal activity, with better results at a concentration of 25%, and with extraction by infusion and decoction. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

8 pages, 260 KiB

Open AccessArticle

First Report of Field Resistance to Afidopyropen, the Novel Pyropene Insecticide, on Bemisia tabaci Mediterranean (Q Biotype) from China

by Ran Wang, Bingli Gao, Wunan Che, Cheng Qu, Xuan Zhou and Chen Luo

Agronomy 2022, 12(3), 724; https://doi.org/10.3390/agronomy12030724 - 17 Mar 2022

Cited by 14 | Viewed by 3538

Abstract

Afidopyropen, a novel biopesticide, is derived from Aspergillus fumigatus, a fungus, and shows promise as a novel insecticidal agent for the management of the whitefly pest Bemisia tabaci in horticultural and economical crop production. In the present work, we monitored the susceptibilities [...] Read more.

Afidopyropen, a novel biopesticide, is derived from Aspergillus fumigatus, a fungus, and shows promise as a novel insecticidal agent for the management of the whitefly pest Bemisia tabaci in horticultural and economical crop production. In the present work, we monitored the susceptibilities of B. tabaci to afidopyropen in 18 field populations, sampled from 9 provinces of China, and found that, in comparison with the susceptible strain (MED-S), B. tabaci from most field populations were highly susceptible, except for the Haidian population (HD) which exhibited an approximately 40-fold increase in resistance. The HD population also displayed significant cross-resistance to sulfoxaflor (14.5-fold) but little cross-resistance to cyantraniliprole, flonicamid, imidacloprid, pymetrozine, and thiamethoxam. Afidopyropen resistance of the HD population was determined to be incomplete dominant and autosomal, and synergism assays demonstrated that P450 monooxygenases could contribute to the field-evolved afidopyropen resistance observed in the HD population. These results will further our understanding of the molecular underpinnings of insecticide resistance in B. tabaci and can inform the development of field-based pest control tactics to slow the development of afidopyropen resistance and to control whiteflies more sustainably. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

16 pages, 4067 KiB

Open AccessArticle

The Effect of Glucosinolates on the Growth and Development of Helicoverpa armigera Larvae and the Expression of Midgut Sulfatase Genes

by Xue Li, Fan Cai, Guli Kuerban, Shaohui Zhang, Chaoyong Li, Ying Zhao, Lin Jin and Xiaoli Ma

Agronomy 2022, 12(2), 306; https://doi.org/10.3390/agronomy12020306 - 25 Jan 2022

Cited by 3 | Viewed by 2705

Abstract

The plant–pest interaction and its mechanisms are a novel research direction for pest control. They provide molecular targets for developing new pesticides and targeted control measures to control insect herbivores. Glucosinolate is a large family of secondary substances found in cruciferous plants that [...] Read more.

The plant–pest interaction and its mechanisms are a novel research direction for pest control. They provide molecular targets for developing new pesticides and targeted control measures to control insect herbivores. Glucosinolate is a large family of secondary substances found in cruciferous plants that are harmful to herbivorous insects. Specialist herbivores have developed specific anti-defense genes and detoxifying mechanisms against glucosinolate from the host plant, but how generalist herbivores respond to glucosinolate at the molecular level is unknown. In this study, we investigated the effects of different glucosinolate concentrations on the growth and development of Helicoverpa armigera. Moreover, the expression of sulfatase genes (HaSulfs) was also checked following exposure to glucosinolate concentrations. The developmental duration of larvae and pre-pupa of H. armigera was significantly increased by 14.79–25.03% after feeding glucosinolate compared to the control. Quantitative Real-Time PCR (RT-qPCR) was carried out to analyze the expression of HaSulf family genes in the midgut of fifth instar larvae of H. armigera. The results showed that the upregulated expression patterns of HaSulf family genes were diversified after feeding at different concentrations. The expression level of HaSulf was detected with the HaSulf antibody. Only the glucosinolate-fed larvae had a visible target band and were mainly distributed in the midgut wall. Taken together, glucosinolate can significantly affect the growth and development of H. armigera larvae. It can induce the expression of HaSulf in the midgut of H. armigera at gene and protein levels. This study could be useful to understand the development of plant-derived insecticides resistance in H. armigera. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

9 pages, 1215 KiB

Open AccessArticle

Physiological and Biochemical Responses to Sublethal Concentrations of the Novel Pyropene Insecticide, Afidopyropen, in Whitefly Bemisia tabaci MED (Q Biotype)

by Xuan Zhou, Ziyi Zhang, Huixin Zheng, Qinghe Zhang, Jingyu Gong, Chuanren Li and Ran Wang

Agronomy 2021, 11(11), 2260; https://doi.org/10.3390/agronomy11112260 - 9 Nov 2021

Cited by 12 | Viewed by 2661

Abstract

Bemisia tabaci is a devastating agricultural insect pest worldwide, and B. tabaci MED (formerly biotype ‘Q’) threatens the production of horticultural and economic crops in China as a growing number of cases of insecticide resistance have issued, highlighting the requirement for alternative methods [...] Read more.

Bemisia tabaci is a devastating agricultural insect pest worldwide, and B. tabaci MED (formerly biotype ‘Q’) threatens the production of horticultural and economic crops in China as a growing number of cases of insecticide resistance have issued, highlighting the requirement for alternative methods and measures of pest management. In the present work, the toxicities of eight popular chemical agents, including the novel pyropene insecticide afidopyropen, on adults of B. tabaci MED were determined, and then physiological and biochemical responses to sublethal concentrations were confirmed. Among all tested chemical agents, afidopyropen exhibited the highest toxicity to adult whiteflies (LC₅₀: 7.38 mg/L). The sublethal effects of afidopyropen were studied at two sublethal concentrations, LC₁₀ (0.53 mg/L) and LC₂₅ (1.84 mg/L), and LC₂₅ treatment extended the duration of growth stages and reduced viabilities in the stages of nymphal, pseudopupae, and adults. The egg-laying days and eggs laid per female were also decreased significantly, as was hatchability in the LC₂₅ treatment. Metabolic enzyme assays suggested that the sublethal effects of LC₂₅ treatment could be ascribable to enhanced detoxification mediated by glutathione S-transferase. In summary, our findings indicate that afidopyropen can be used as a chemical agent for the management of B. tabaci MED whiteflies. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

11 pages, 1708 KiB

Open AccessEditor’s ChoiceArticle

Ovicidal and Physiological Effects of Essential Oils Extracted from Six Medicinal Plants on the Elm Leaf Beetle, Xanthogaleruca luteola (Mull.)

by Bita Valizadeh, Jalal Jalali Sendi, Marziyeh Oftadeh, Asgar Ebadollahi and Patcharin Krutmuang

Agronomy 2021, 11(10), 2015; https://doi.org/10.3390/agronomy11102015 - 7 Oct 2021

Cited by 9 | Viewed by 2744

Abstract

Plant essential oils may serve as safe alternatives to detrimental synthetic pesticides due to relatively lower side effects on the environment and non-targeted organisms. The current study was conducted to investigate the ovicidal toxicity and physiological disruptions of six medicinal plant essential oils, [...] Read more.

Plant essential oils may serve as safe alternatives to detrimental synthetic pesticides due to relatively lower side effects on the environment and non-targeted organisms. The current study was conducted to investigate the ovicidal toxicity and physiological disruptions of six medicinal plant essential oils, including Artemisia annua L., Lavandula angustifolia Mill., Origanum vulgare L., Rosmarinus officinalis Spenn., Satureja hortensis L., and Thymus vulgaris L., on elm leaf beetle Xanthogaleruca luteola (Mull.). The LC₅₀ (Lethal Concentration to kill 50% of tested insects) values of 122.8, 287.5, 152.8, 180.6, 315.9, and 1366.2 ppm were recorded for T. vulgaris, L. angustifolia, A. annua, S. hortensis, R. officinalis, and O. vulgare, respectively, 72 h after treatment of 3-day-old eggs of the pest. Significant decreases in the amounts of glucose, protein, and triglyceride macromolecules were also observed after treatment. The application of essential oils derived from T. vulgaris, A. annua, and S. hortensis at 400 ppm revealed 100% ovicidal activity. Accordingly, tested essential oils, particularly the essential oil of T. vulgaris, have been promising potential as biorational insecticides in the management of X. luteola. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

12 pages, 3411 KiB

Open AccessArticle

VaCRK2 Mediates Gray Mold Resistance in Vitis amurensis by Activating the Jasmonate Signaling Pathway

by Tinggang Li, Huanhuan Gao, Xiaoning Tang and Dongying Gong

Agronomy 2021, 11(8), 1672; https://doi.org/10.3390/agronomy11081672 - 23 Aug 2021

Cited by 3 | Viewed by 2292

Abstract

Cysteine-rich receptor-like kinases (CRKs) are ubiquitous plant receptor-like kinases, which play a significant role in plant disease resistance. Gray mold is an economically important disease of grapes caused by Botrytis cinerea. However, CRK genes and their function in gray mold disease resistance [...] Read more.

Cysteine-rich receptor-like kinases (CRKs) are ubiquitous plant receptor-like kinases, which play a significant role in plant disease resistance. Gray mold is an economically important disease of grapes caused by Botrytis cinerea. However, CRK genes and their function in gray mold disease resistance in grapes have not been elucidated. This study aimed to identify and characterize CRKs in grapes and determine their role in gray mold resistance. Four CRKs were identified in Vitis amurensis and named VaCRK1–VaCRK4 according to their genomic distribution. The four VaCRKs were ectopically expressed in Arabidopsis thaliana to study their function in defense response against B. cinerea. Heterologous expression of VaCRK2 in A. thaliana conferred resistance to B. cinerea. VaCRK2 expression in gray mold-resistant grape cultivar increased significantly after B. cinerea inoculation and methyl jasmonate treatment. Furthermore, the expression of jasmonic acid (JA) signaling pathway-related genes in VaCRK2 overexpression lines of A. thaliana was significantly increased after B. cinerea inoculation, leading to the upregulation of pathogenesis-related (PR) genes and reactive oxygen species (ROS) accumulation. Overall, these results suggest that VaCRK2 confers resistance to B. cinerea by activating PR gene expression and oxidative burst through the JA signaling pathway. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

12 pages, 3050 KiB

Open AccessArticle

The Sensitivity of Field Populations of Metopolophium dirhodum (Walker) (Hemiptera: Aphididae) to Seven Insecticides in Northern China

by Peipan Gong, Xinan Li, Chao Wang, Saige Zhu, Qiuchi Li, Yunhui Zhang, Xiangrui Li, Guangkuo Li, Enliang Liu, Haifeng Gao, Xueqing Yang and Xun Zhu

Agronomy 2021, 11(8), 1556; https://doi.org/10.3390/agronomy11081556 - 4 Aug 2021

Cited by 11 | Viewed by 2317

Abstract

Insect pests are primarily controlled by insecticides. However, the sensitivity decreases and insecticide resistance is problematic for the effective management of agriculturally important insects, including Metopolophium dirhodum, which is an aphid that commonly feeds on cereals. The insecticide sensitivity status and potential [...] Read more.

Insect pests are primarily controlled by insecticides. However, the sensitivity decreases and insecticide resistance is problematic for the effective management of agriculturally important insects, including Metopolophium dirhodum, which is an aphid that commonly feeds on cereals. The insecticide sensitivity status and potential resistance of M. dirhodum field populations remain relatively unknown. In this study, the susceptibility of 19 M. dirhodum populations from seven provinces in Northern China to neonicotinoids, pyrethroids, organophosphates, and a macrolide (abamectin) was determined in 2017–2019. The results indicated that two populations were highly resistant to thiamethoxam, with a relative resistance ratio (RLR) of 134.03 and 103.03, whereas one population was highly resistant to beta-cypermethrin (RLR of 121.42). On the basis of the RLR, the tested M. dirhodum populations ranging from susceptible to showing moderate levels of resistance to imidacloprid (RLR of 1.50 to 57.29), omethoate (RLR of 1.07 to 18.73), and abamectin (RLR of 1.10 to 25.89), but they were ranging from susceptible to showing tolerance or low levels of resistance to bifenthrin (RLR of 1.14 to 6.02) and chlorpyrifos (RLR of 1.11 to 7.59). Furthermore, a pair-wise correlation analysis revealed a significant correlation between the median lethal concentrations (LC₅₀) for beta-cypermethrin and thiamethoxam, reflecting the cross-resistance between these two insecticides. The data obtained in our study provide timely information about aphid insecticide sensitivity, which may be used to delay the evolution of M. dirhodum insecticide resistance in Northern China. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

15 pages, 3290 KiB

Open AccessArticle

Effect of Paclobutrazol on the Physiology and Biochemistry of Ophiopogon japonicus

by Zezhou Zhang, Ruixing Li, Deyong Chen, Jieyin Chen, Ouli Xiao, Zhiqiang Kong and Xiaofeng Dai

Agronomy 2021, 11(8), 1533; https://doi.org/10.3390/agronomy11081533 - 30 Jul 2021

Viewed by 3014

Abstract

Ophiopogon japonicus is a commonly used Chinese medicine with multiple pharmacological effects. To increase the yield of O. japonicus, paclobutrazol is widely used during the cultivation, and residues of paclobutrazol cause undesired side effects of O. japonicus. In this study, the [...] Read more.

Ophiopogon japonicus is a commonly used Chinese medicine with multiple pharmacological effects. To increase the yield of O. japonicus, paclobutrazol is widely used during the cultivation, and residues of paclobutrazol cause undesired side effects of O. japonicus. In this study, the effect of different concentrations of paclobutrazol on O. japonicus was investigated, and the final residual amount of paclobutrazol in the plant sample was determined by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS); cell morphology was observed by transmission electron microscopy. The inhibitory effect of paclobutrazol on plant height and the stimulatory effect on root elongation were concentration-dependent from 0.6 to 11.3 g/L, reaching a maximum of about 28% and 67%, respectively. However, when the concentration was 22.5 g/L, these effects were significantly weakened, and the same trend was observed for the tuber root weight. Paclobutrazol caused the cell wall of O. japonicus to thicken, making the cells smaller and more densely arranged. Paclobutrazol also inhibited bacterial growth, irrespective of the concentration. Considering the residual concentration after application and the effects on growth, the application of 1.3 g/L or 2.8 g/L paclobutrazol can increase the accumulation of effective ingredients while promoting production, reducing application costs, and maximizing farmers’ profit. Full article

(This article belongs to the Special Issue Advances in Pesticide Discovery and Application)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Advances in Pesticide Discovery and Application

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (13 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI