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The flowering of tea plant Camellia sinensis (L.) O. Kuntze consumes large amounts of water and nutrients and negatively affects the growth of tea plant. The effects of plant growth regulators, including ethephon, α-naphthalene acetic acid, salicylic acid, chlormequat, and paclobutrazol, were investigated on the abscission of flower buds and flowers on the tea plant. The occurrence of anthracnose Gloeosporium theae-sinesis Miyake and tea green leafhopper Empoasca onukii Matsuda on the tea plant were also investigated after exogenous application of these chemicals. Ethephon (at 800, 1200, and 1600 mg l−1), paclobutrazol (at 150, 300, and 600 mg l−1), and chlormequat (at 300 and 600 mg l−1) significantly promoted the abscission of flower buds and flowers and finally reduced the number of tea flowers in the tea plantations. These three compounds had almost no effect on the number of tea shoots. Moreover, paclobutrazol and chlormequat also suppressed the occurrence of anthracnose on the tea plant. Paclobutrazol and chlormequat induced the high catalase and peroxidase activities in the tea plant. In addition, the photosynthetic characteristics and biochemical components such as tea polyphenols in the tea plant leaves treated with plant growth regulators decreased significantly. There was a certain correlation between effects of ethephon and paclobutrazol on flower abscission and the expression of ACS and ETR. Overall, plant growth regulators could effectively reduce tea flowers and suppress anthracnose on the tea plant.

Tea, which is usually made from the new shoots of tea plants (Camellia sinensis), is one of the most popular and healthy beverages. The tenderness of new shoots plays a critical role in the production of high-quality tea; however, the factors affecting the tenderness of the new shoots of tea have not been extensively studied. Here, we show that cellulose accumulation is negatively correlated with the tenderness of new shoots, including leaves and stems, by characterizing the cellulose content and visualizing cellulose in the new shoots of two cultivars ("Huangjinya" and "Yujinxiang") via toluidine blue staining. We further found that the number of cells with secondary cell walls (SCWs) and the thickness of SCWs increased with the maturity degree of stems in both cultivars. Because cellulose is the most abundant polymer in SCW, we next identified three cellulose synthase CsCesAs, CsCesA4, 7, and 8A, through homologous alignment with Arabidopsis AtCesAs. Protein sequence analysis revealed that these proteins were closely related based on the phylogenetic analysis. We finally showed that the gene expression of the three CsCesAs was positively correlated with the maturity degree and cellulose content of the new shoots. Thus, our data suggest that cellulose accumulation, especially in the SCWs, is negatively correlated with the tenderness of new shoots in tea plants.

‘Huangjinya’ is a novel light-sensitive albino tea cultivar. Previously we have found that the leaves exhibit varying degrees of yellow coloration after being exposed to different light qualities, including red light (RL), blue light (BL), red + blue light (RB) and white light (WL). To understand the transcriptional response of different light qualities in leaf coloration of ‘Huangjinya’, RNA-seq analysis with three biological replicates was performed to identify differentially expressed genes (DEGs) involved in pigment metabolism pathways. With regard to porphyrin and chlorophyll metabolism, the protochlorophyllide oxidoreductase (POR) was upregulated and chlorophyllase (Chlase) was downregulated under RL compared with WL, which contributed to high chlorophyll content in ‘Huangjinya’. The upregulated POR and magnesium chelatase H subunit (CHLH) were identified under RB. BL significantly promoted carotenoid biosynthesis, accompanied by the related upregulated genes. However, upregulated xanthoxin dehydrogenase (ABA2) reduced carotenoid content under BL. Zeaxanthin epoxidase (ZEP) was upregulated and ABA2 was downregulated under RB, resulting in high accumulation of carotenoid content. BL and RL upregulated expressions of genes involved in flavonoid biosynthesis in ‘Huangjinya’. Differential expressions of genes involved in flavonoid biosynthesis was considered as the results of leaf color change. In addition, the genes related to photosynthesis were downregulated under RL, whereas these were upregulated under BL when compared with WL. In conclusion, the effect of light quality on the leaf coloration of ‘Huangjinya’ was mainly dependent on chlorophyll content by altering corresponding genes expressions. RL may promote the accumulation of chlorophyll in ‘Huangjinya’ leaves by upregulating the expression of genes related to chlorophyll synthesis (e.g., POR) and downregulating expression of genes related to chlorophyll degradation (e.g., Chlase). BL could upregulate the expression of genes related to both biosynthesis (e.g., POR, hemA) and degradation (e.g., Chlase) of chlorophyll, resulting in little change in leaf color of ‘Huangjinya’ under blue light when compared with white light. Upregulated genes involved in chlorophyll biosynthesis (e.g., POR, CHLH) induced greener color of ‘Huangjinya’ treated with RB.

Sulfoxaflor is the first sulfoximine insecticide registered for controlling piercing-sucking pests in agricultural settings. Parasitoid wasps of the genus Trichogramma are effective biocontrol agents against a wide range of insect pests. In this study, we explored the impacts of sulfoxaflor on Trichogramma dendrolimi, Trichogramma ostriniae and Trichogramma confusum under lethal and sublethal-concentration exposure in laboratory. The acute toxicity test indicated that sulfoxaflor possesses high toxicity to T. dendrolimi, T. ostriniae and T. confusum with LC50s of 0.12, 0.24 and 0.32 mg a.i. L−1, respectively. Parasitism of the three Trichogramma spp. were significantly impaired when the host eggs were exposed to low lethal concentrations of sulfoxaflor. The adult emergence rates of the subsequent generation of T. dendrolimi were compromised in all treatments. However, adult emergence rates of T. ostriniae and T. confusum were not profoundly affected at 0.0215 mg a.i. L−1. Results of IOBC categorization demonstrated that sulfoxaflor at 0.0215 mg a.i. L−1 was harmless to the parasitism of three Trichogramma spp., but being harmless to the adult emergence of their progeny at all test concentrations. Overall, application of sulfoxaflor in association with T. dendrolimi, T. ostriniae and T. confusum should be carefully schemed in agricultural environments.

Light quality is considered one of the most important environmental factors for plant photomorphogenesis. ‘Huangjinya’ is a novel light-sensitive albino tea cultivar with bright yellow leaves and a high amino acid content. To investigate the effects of light quality on the color change process in ‘Huangjinya’, the leaf color phenotypes, photosynthetic pigments, chlorophyll fluorescence parameters, and photoreceptor gene expression in ‘Huangjinya’ were evaluated when the tea plants were exposed to red, blue, red + blue (red: blue = 1:1), and white LED light for 15 days. Among the four different light treatments, the highest contents of chlorophyll a, b and a + b in the greenest ‘Huangjinya’ leaves were obtained under red light, while the lowest contents were obtained under white light. Light quality noticeably affected some chlorophyll fluorescence parameters of ‘Huangjinya’. Lower ΦPSII and higher NPQ values of the tea plant leaves were found under the red and blue light treatments than under the white light treatment. The photoreceptor phytochrome genes CsPHYA, CsPHYB, and CsPHYE were upregulated in ‘Huangjinya’ when exposed to red light. In addition, blue light induced high expression levels of the cryptochrome genes CsCRY1 and CsCRY2 in ‘Huangjinya’. The lowest expression levels of both CsPHY and CsCRY were found under white light among the four different light qualities. In conclusion, the leaf color of ‘Huangjinya’ remained green under red light, which was partly due to high chlorophyll contents. Moreover, in ‘Huangjinya’, red light strongly induced high expression levels of the phytochrome genes CsPHYA and CsPHYB, which may be involved in chlorophyll synthesis and leaf color changes. Interestingly, the yellowest ‘Huangjinya’ leaves were obtained under white light, and the spectrum of white light was obviously different from that of the other lights at the wavelengths of 510˜610 nm. We hypothesized that there may be a photoreceptor in this range that senses and transmits light signals to induce the leaf color of ‘Huangjinya’ to remain yellow. In addition, we also found that red light increased the tea shoot length and slightly reduced the leaf area, while blue light induced tea shoot elongation and caused little leaf expansion.

Background The black cutworm Agrotis ipsilon is the most destructive early season insect pest of corn. In this study, the control efficiency of cyantraniliprole seed treatment against A. ipsilon was evaluated, and the residual concentrations of cyantraniliprole and its metabolite J9Z38 in the stalks of corn seedlings and soil were investigated. Results Plant pot experiments showed that A. ipsilon larval mortality was greater than 92% and that the percentage of corn seedlings damaged by A. ipsilon was less than 24% when corn seeds were treated with cyantraniliprole at 2 and 4 g AI kg-1 seed. Cyantraniliprole seed treatment at a dosage of 2 g AI kg-1 seed significantly reduced A. ipsilon infestation compared to chlorantraniliprole and clothianidin seed treatments in corn fields. Cyantraniliprole seed treatment resulted in more persistent control efficiency of A. ipsilon in spring than in summer. Cyantraniliprole and J9Z38 residues in corn stalks and soil degraded more slowly in the spring than in the summer. Conclusion Cyantraniliprole used as a seed treatment can protect corn plants from A. ipsilon infestations throughout the seedling stage. The high biological activity of cyantraniliprole was consistent with the residue levels of cyantraniliprole in the corn stalks and soil. © 2018 Society of Chemical Industry.

Tribolium castaneum (Herbst) is an important pest of stored grain, and benzoquinones secreted by this pest are harmful to humans. T. castaneum has developed strong resistance to fumigants, and an ecofriendly alternative for managing T. castaneum is urgently needed. 1-Octen-3-ol is a major volatile compound present in many mushrooms and fungi. In the current study, the direct toxicity and sublethal and transgenerational effects of 1-octen-3-ol on T. castaneum were investigated. Our results showed that 1-octen-3-ol had strong insecticidal activity against all developmental stages of T. castaneum and repelled T. castaneum adults. 1-Octen-3-ol showed negative effects on the development and reproduction of parental T. castaneum and the subsequent generation: LC30 and LC50 treatments significantly decreased the pupa and adult weights, pupation and emergence rates and fecundity of the parental generation. In addition, LC50 treatment shortened the larval and pupal periods. In the unexposed progeny (F1) of 1-octen-3-ol-exposed parents, decreased survival and pupation rates as well as reduced pupa and adult weights were observed under LC30 and LC50 treatments. In addition, a model food-system experiment showed that 1-octen-3-ol at 98 μL/L exhibited an efficacy of 100% after 7 days of fumigation and completely eliminated T. castaneum offspring. Although a higher concentration of 1-octen-3-ol was needed to achieve an efficacy equal to that of the positive control, dichlorvos (DDVP), 1-octen-3-ol promoted the seedling growth of wheat seeds, suggesting that the concentration used was not only acceptable but also beneficial for wheat seeds. Overall, 1-octen-3-ol seems to be a promising candidate for use as a fumigant and repellent against T. castaneum as well as a seed protectant.

The tea green leafhopper Empoasca onukii Matsuda (Hemiptera: Cicadellidae), the orange spiny whitefly, Aleurocanthus spiniferus (Quaintanca) (Hemiptera: Aleyrodidae), and the green plant bugs Apolygus lucorum Meyer-Dür (Hemiptera: Miridae) are the important piercing–sucking herbivores in tea trees Camellia sinensis (L.) O. Kuntze (Theaceae). The goal of this study was to evaluate the laboratory toxicities and field control efficacies of botanical insecticides including matrine, azadirachtin, veratrine, and pyrethrin to three tea pests. Via leaf-dip bioassay, toxicity tests with botanical insecticides indicated that there were significant differences between the LC50 values for botanical insecticides within the same insect species. Matrine had the highest toxicity to E. onukii, A. spiniferus, and A. lucorum with the LC50 values of 2.35, 13.10, and 44.88 mg/liter, respectively. Field tests showed that, among four botanical insecticides, matrine at dose of 9 g a.i. ha−1 can significantly reduce the numbers of E. onukii and A. spiniferus and the infestation of A. lucorum on the tea plants. Furthermore, botanical insecticides matrine and azadirachtin had no obvious influence on the coccinellids, spiders, and parasitoids densities in tea plantations. The results of this study indicated that use of botanical insecticides, such as matrine, has the potential to manipulate the population of E. onukii, A. spiniferus, and A. lucorum and will be an effective and environmentally compatible strategy for the control of tea pests.

BACKGROUND The red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), is an important stored-product pest that is distributed worldwide and has developed resistance to many insecticides. Identifying novel and effective alternative insecticides is important for the control of T. castaneum. The volatile compound benzothiazole has been identified as having great acute toxic activity against T. castaneum. However, a comprehensive evaluation of a new insecticide should include both direct toxic effects and sublethal effects. The aim of this study was therefore to evaluate the effects of benzothiazole on the development and reproduction of T. castaneum. RESULTS Exposure of fourth-instar larvae to lethal and sublethal concentrations of benzothiazole (LC10 , LC30 and LC50 ) significantly decreased pupation rates, food intake and growth rates in T. castaneum. Larval duration was significantly reduced by approximately 1 day in the LC30 and LC50 treatment groups. The LC50 benzothiazole caused a significant decrease in the weight of pupae and adults, fecundity and egg hatchability. Increased and decreased nutrient (carbohydrate and lipid) contents were observed in surviving larvae and pupae, respectively. The LC30 and LC50 treatments caused the down-regulation of five growth-positive regulated genes (PI3K, AKT, CyclinE, S6K1 and S6K2) and the up-regulation of two growth-negative regulated genes (4EBP and FOXO). CONCLUSION Benzothiazole presented adverse effects on the development and reproduction of T. castaneum, further supporting benzothiazole as a highly active compound in stored-product protection. © 2020 Society of Chemical Industry.

Background In the context of the resistance development and health risks of currently used fumigants, it is urgent to seek more effective and ecofriendly compounds for stored-product pest control. The microbial volatile compound benzothiazole is known to have fungicidal and insecticidal activity; however, its detailed efficacy on storage pests is largely unknown. Results Benzothiazole was identified for its great ovicidal, larvicidal, pupicidal and adulticidal activity against Tribolium castaneum, and exhibited potent repellency against T. castaneum. The benzothiazole concentrations and developmental stage of T. castaneum were the key factors affecting the insecticidal effects. Adults of T. castaneum exposed to benzothiazole for as long as 168 h showed a decrease in progeny production. Based on 7 days of fumigation in the model food system, benzothiazole at 0.12 mg mL-1 provided an efficacy of 96% and completely inhibited the number of offspring. Safety profile assessment showed that benzothiazole did not affect the germination rate of wheat seeds but had a slight negative effect on seedling growth. However, sufficient ventilation and soil nutrients could relieve this adverse impact. Conclusion Benzothiazole is a strong fumigant and repellent against T. castaneum. This study provides a good perspective of novel ways to control T. castaneum. © 2020 Society of Chemical Industry.

The increasing demand for lessening the chemical input in agricultural ecosystems requires an efficient combination of pesticides and biological controls. Thus, fully understanding the compatibility of pesticides and beneficial arthropod predators is helpful and essential. In this study, we evaluated the influence of nitenpyram on both larvae and adults of Coccinella septempunctata using exposure doses of 10, 25, 50, 100, and 150% of the maximum recommended field rate (MRFR) (3, 7.5, 15, 30, and 45 g a.i. ha−1, respectively) and a blank control based on a preliminary acute 72-h toxicity experiment. In the long-term test, the LR50 (application rate causing the mortality of 50% of the individuals) of nitenpyram for C. septempunctata decreased from 73.43 to 63.0 g a.i. ha−1, while the HQ (hazard quotient) values remained below the threshold value of 2. Nitenpyram did not significantly influence the survival rate, fecundity, pupation, or adult emergence at 150% of the label rate (lowest LR50 = 63.0 g a.i. ha−1), and its demonstrated NOER (No Observed Effect application Rates) values are all above 45 g a.i. ha−1. Likewise, the total developmental time and egg hatchability were not significantly affected at 100% of the label rate (NOER = 30 g a.i. ha−1). The assessment of the total effect (E) suggested that nitenpyram could be classified as harmless to C. septempunctata below/at a dose of 30 g a.i. ha−1. The lowest LR50 and NOER values were both above the maximum recommended field application rate for nitenpyram (30 g a.i. ha−1) for controlling aphids in China. All results indicated that the on-label use of nitenpyram is compatible with the natural enemy C. septempunctata in agricultural ecosystems.

BACKGROUND Gray mold is a ubiquitous destructive plant disease found worldwide. To avoid the shortcomings of conventional spraying systems for controlling this disease, such as high selection pressure on Botrytis cinerea for resistance and fungicide waste resulting from spray drift, a precisely targeted application strategy of dipping young cucumber fruit in a mixture of fungicide and forchlorfenuron (plant growth regulator, PGR) during the bloom period to control cucumber gray mold was developed in the current study. RESULTS Without leaving above-limit residues in cucumber fruits, dipping in fludioxonil at 30 mg L-1 provided a greater efficacy (85.4%) against cucumber gray mold than did spraying at 100 mg L-1 (76.4%). Importantly, fludioxonil mixed with forchlorfenuron from 25 to 35 mg L-1 increased the yield of cucumbers by 26.2-36.7% compared to dipping fruit only in forchlorfenuron. The increased yield may be a benefit of controlling gray mold. CONCLUSION Dipping fruit in fungicides and PGRs seems to be a potential precisely targeted application strategy to not only control cucumber gray mold effectively but also, through the action of PGRs, to increase the cucumber yield. This novel application method is believed to have a bright prospect in cucumber production in Chinese solar glasshouses. © 2018 Society of Chemical Industry.

Bradysia odoriphaga is the major pest affecting Chinese chive production, and in China, it has developed widespread resistance to organophosphorus insecticides. Chlorfenapyr is a promising pyrrole insecticide with a unique mechanism of action that does not confer cross-resistance to neurotoxic insecticides. However, the effect of chlorfenapyr on organophosphate-resistant B. odoriphaga is not well understood. The present study evaluated the potential of chlorfenapyr for the control of phoxim-resistant B. odoriphaga. The results showed that chlorfenapyr had significant insecticidal activity to B. odoriphaga in multiple developmental stages, and there were no significant differences in susceptibility between the field (phoxim-resistant) and laboratory (phoxim-susceptible) populations. The pot experiment and field trials confirmed the results of our laboratory bioassays. In the field trial, chlorfenapyr applied at 3.0, 6.0, or 12.0 kg of active ingredient (a.i.)/ha significantly decreased the number of B. odoriphaga and improved the yield compared to phoxim at 6.0 kg of a.i./ha and the control conditions. Moreover, the final residues of chlorfenapyr on plants were below the maximum residue limits (MRLs) as a result of its non-systemic activity. These results demonstrate that chlorfenapyr has potential as a potent alternative to phoxim for controlling B. odoriphaga.

Wireworms, the larval stage of click beetles (Coleoptera: Elateridae), are a major pest in the production of winter wheat in North China, and effective population control is often essential for cost-effective crop production. In this study, six neonicotinoids alone, and three in combination with fipronil as seed treatments were investigated to determine their effects on the management of the wireworm Pleonomus canaliculatus (Faldermann) in winter wheat fields. Thiamethoxam, clothianidin and imidacloprid seed treatments at a rate of 360 g AI 100 kg−1 seed significantly reduced infestations of wireworm in wheat seedlings. Relatively higher correlations were observed between the application rates of thiamethoxam, clothianidin and imidacloprid and wireworm damage percentage, but relatively lower correlations were found between application rates and wireworm populations. Furthermore, seed treated with fipronil (40 g AI 100 kg−1 seed), thiamethoxam (360 g AI 100 kg−1 seed), thiamethoxam + fipronil and clothianidin + fipronil (360 + 40 g AI 100 kg−1 seed) significantly decreased wireworm damage and population densities of P. canaliculatus. An additive interaction was observed between thiamethoxam and fipronil. Thiamethoxam and fipronil can be combined to provide growers with an option for controlling wireworm populations and can comprise a key component in integrated management of the wireworm in winter wheat production.

As for developing effective integrated pest management (IPM), it is necessary to understand the sublethal effects of common insecticides on the non-target beneficial arthropods. In this lab-scale study, the sublethal effects of two anthranilic diamide insecticides chlorantraniliprole and cyantraniliprole on the populations of 7-spot ladybird Coccinella septempunctata (Coleoptera: Coccinellidae) were determined and compared using an age-stage, TWO-SEX life table and CONSUME-MSChart computer program. Cyantraniliprole at low-lethal concentrations of 1 and 10 mg L−1 significantly prolonged the larval stages and reduced the total adult longevity, compared with the control. Additionally, the net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (λ), and mean generation time (T) were significantly reduced in the group treated with 10 mg L−1 of cyantraniliprole. Similarly, the net predation (C0), the finite predation rate (ω), and stable predation rate (ψ) were significantly reduced by cyantraniliprole at 1 and 10 mg L−1. In contrast, no significant difference in the demographic parameters above was determined for chlorantraniliprole at 1 mg L−1. Therefore, C. septempunctata population may develop faster and possess greater predation potential against aphids under the exposure of chlorantraniliprole, compared to cyantraniliprole. Chlorantraniliprole may be a preference to cyantraniliprole as a combined alternative with ladybeetle predators in IPM framework.

Isopyrazam is a new broad-spectrum, foliar-absorbed and -translocated succinate dehydrogenase inhibitor fungicide. In this study, 159 Botrytis cinerea isolates collected from different geographical regions of Shandong Province of China were characterized for baseline sensitivity to isopyrazam. Furthermore, the protective and curative activity of isopyrazam on strawberry fruit and the control efficacy in the field were also determined. In contrast to its mycelial growth, the spore germination of B. cinerea was inhibited completely by lower concentrations of isopyrazam, about 1 μg ml−1 on yeast-peptone-acetate medium. Frequency distributions of isopyrazam 50% effective concentration (EC50) values were unimodal curves, with mean EC50 values of 0.07 ± 0.04 (standard deviation) and 0.68 ± 0.36 μg ml−1 for the inhibition of spore germination and mycelial growth, respectively. In addition, there was no positive multiple resistance between isopyrazam and other classes of botryticides such as diethofencarb, iprodione, pyrimethanil, or SYP-Z048. In field trials conducted during 2014 and 2015, isopyrazam used at a concentration of active ingredient at 150 and 200 g ha−1 provided a control efficacy ranging from 76.7 to 87.8% on leaves and from 81.5 to 90.7% on fruit. These results suggest that isopyrazam has the potential to play an important role in the management of gray mold.

Bradysia odoriphaga (Diptera: Sciaridae) is the major pest that damages Chinese chive production. As a volatile compound derived from microbial secondary metabolites, benzothiazole has been determined to possess fumigant activity against B. odoriphaga. However, the mechanism of action of benzothiazole is not well understood. In the present study, fourth-instar larvae of B. odoriphaga were exposed to LC10 and LC30 of benzothiazole. Sublethal concentrations (LC10 and LC30) of benzothiazole significantly reduced the food consumption of the larvae on the second day after treatment (2 DAT). However, there were no significant changes in pupal weight among the different treatments. We also measured the protein, lipid, carbohydrate, and trehalose contents and the digestive enzyme activities of the larvae, and the results suggest that benzothiazole reduced the nutrient accumulation and decreased the digestive enzyme activities of B. odoriphaga. In addition, the activity of glutathione S-transferase was significantly decreased at 6h after treatment with benzothiazole, whereas general esterase activities were significantly increased at 6 and 24h after treatment. The results of this study indicate that benzothiazole interferes in the normal food consumption and digestion process by decreasing the activities of digestive enzymes. These results provide valuable information for understanding the toxicity of benzothiazole and for exploring volatile compound for the control of this pest.

The application of pesticide microcapsules (MCs) in agriculture is becoming more and more popular. In this study, the effects of different wall materials on the stomach toxicity, contact toxicity, length of efficacy, and photolysis characteristics of pesticide microcapsules were investigated. The results showed that microencapsulation reduced the stomach and contact toxicities of phoxim and prolonged the efficacy of this light-sensitive chemical in the greenhouse test. Neither of the degradation curves for microencapsulated phoxim under ultraviolet light fit a first-order model, although the emulsifiable concentrate (EC) degradation curve fit it well. The phoxim-loaded polyurea microcapsules (PUA-MCs) showed significantly increased UV-resistance ability, stomach toxicity, and contact toxicity compared with the phoxim-loaded urea-formaldehyde microcapsules (UF-MCs). These experiments indicated that it is crucial to select the appropriate wall materials for pesticide microcapsules on the basis of application sites and physicochemical properties of pesticide active ingredients.

The chive maggot, Bradysia odoriphaga (Diptera: Sciaridae), is the major pest that damages Chinese chive in China. Benzothiazole is a volatile compound derived from microorganisms secondary metabolites and has fumigant activity against B. odoriphaga. However, the sublethal effects of benzothiazole need to be evaluated before registration and application, to fully understand the potential for control of this pest. Laboratory investigations showed that sublethal concentrations (LC10 and LC30) of benzothiazole decreased the survival rate and the fecundity of B. odoriphaga compared with control. However, the developmental times of eggs, larvae and pupae, and the total preoviposition period were prolonged. Additionally, population parameters were significantly affected in the treated groups. The intrinsic rate of increase (r m ) decreased to 0.1391 (LC10) and 0.1140 (LC30) day-1 compared with the control population (0.1589 day-1). The net reproductive rate (R 0 ) in the control was 54.39 offspring/individual, whereas the R 0 decreased to 41.80 and 25.08 offspring/individual in the LC10 and LC30 treatments, respectively. This study demonstrated that sublethal concentrations of benzothiazole adversely affected the developmental time, fecundity and life table parameters of B. odoriphaga. Therefore, benzothiazole has the potential to be exploited as a natural derived fumigant for the control of this pest.

With the widespread adoption of no-tillage technology, outbreaks of thrips have caused serious damage to summer corn fields in China. Therefore, effective control of pest populations is often essential for cost-effective crop production. In this study, experiments were conducted in 2014 and 2015 to determine the control efficacy of seven neonicotinoid insecticide seed treatments against corn thrips and the effects of these treatments on natural enemy population densities and emergence rates, seedling characteristics, and yield of corn. The results showed that among the tested neonicotinoid seed treatments, thiamethoxam (1.0 and 2.0 g active ingredient (AI)/kg of seeds), clothianidin (1.0 and 2.0 g AI/kg of seeds), and imidacloprid (2.0 g AI/kg of seeds) showed the highest control efficacy against corn thrips throughout the corn growing season. Seed treatments with acetamiprid, nitenpyram, dinotefuran, and thiacloprid at rates of 1.0 and 2.0 g AI/kg of seeds were difficult to effectively control thrips on summer corn. Neonicotinoid seed treatments showed no adverse effects on the numbers of spiders and lady beetles. Furthermore, treatments did not negatively influence the seedling growth or development of corn but did prevent yield losses. Therefore, treating corn seeds with thiamethoxam, clothianidin, and imidacloprid can provide effective protection against early-season thrips and reduce yield losses under field conditions.

Seven-spot ladybird beetles, Coccinella septempunctata L., are critical aphidophagous predators in the agricultural environment. Thiamethoxam, a neonicotinoid insecticide, is commonly used for controlling pests but impairs their natural enemies at the same time. To improve effective IPM (integrated pest management) strategies, we evaluated the sublethal and transgenerational effects of thiamethoxam on C. septempunctata. Our results showed that thiamethoxam at doses of 0.1 × LC10 (0.053 mg L−1) and LC10 (0.53 mg L−1) significantly reduced adult emergence, fecundity and fertility of the parental generation. In unexposed progeny (F1) of thiamethoxam-exposed parents, at the two doses 0.1 × LC10 and LC10, the larval stage was prolonged, and total longevity was decreased by 18.76 and 24.46%, respectively. The higher concentrations (0.1 × LC10 and LC10) also decreased the fecundity by 33.74 and 46.56%, respectively, and the oviposition period by 19.67 and 25.01%, respectively. In addition, demographic parameters including the intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), and mean generation time (T) were significantly reduced when exposed to LC10. Moreover, the predation activity of the F1 generation was reduced by the transgenerational effects of LC10. These results disclose negative influence of thiamethoxam at sublethal concentrations on this ladybird predator and its subsequent generation.

The black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), has been considered a major insect pest in China that causes damage to corn at the seeding stage. The present study measured the lethal and sublethal effects of the neonicotinoid insecticide clothianidin on A. ipsilon. Clothianidin, incorporated using an artificial diet, exhibited signs of active toxicity on fourth-instar larvae of A. ipsilon, with a 50%-lethal concentration (LC50) of 27.77 µg/g. Clothianidin at the LC20 and LC40 levels impaired the normal development of A. ipsilon by prolonging the larval period, decreasing the rate of pupation and eclosion, reducing longevity, shortening the oviposition period, and reducing the fecundity of female adults. Consequently, these effects resulted in the reduction of some population parameter values of A. ipsilon, including the intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R0), along with an increase in the mean generation time (T). However, stimulatory effects, i.e., hormesis, on reproduction were observed in A. ipsilon exposed to an LC5 level based on the fecundity (2,213.62 eggs per female) and net reproductive rate (R0) (863.04 offspring per individual), which were significantly higher than values in the control group (1,344.77 eggs per female and 591.82 offspring per individual). Therefore, the results obtained in this study may assist in the development of optimized integrated pest management strategies, although the results require further study for corroboration under real cropping conditions.

The tea green leafhopper, Empoasca onukii Matsuda (Hemiptera: Cicadellidae), is an economically important pest of tea crops, Camellia sinensis (L.) O. Kuntze (Ericales: Theaceae), in China. The morphological, physiological, and biochemical changes of two tea cultivars, the normal green tea cultivar 'Fudingdabai' and the novel chlorophyll-deficient albino cultivar 'Huangjinya', infested by E. onukii were investigated to determine the tolerance of different tea cultivars to E. onukii attack. E.onukii infestation affected the growth of tea plants, and decreased the shoot length, leaf area, leaf thickness, and stem diameter. Also, E. onukii infestation lowered the thicknesses of upper epidermis, palisade tissue, and spongy tissue of leaves, and the parenchyma tissue thickness and pith diameter of stem internode. E.onukii infestation reduced the chlorophyll a, b and carotenoid contents within the leaves of 'Huangjinya,' which further influenced the photosynthetic rate. The maximum quantum yield and actual photochemical efficiency of photosystem II, and non-photochemical quenching in 'Huangjinya' were inhibited under E. onukii infestation. Peroxidase activity of E. onukii-infested 'Huangjinya' increased more than superoxide dismutase and catalase. In addition, E. onukii feeding changed the contents of free amino acids, tea polyphenols, caffeine, and catechins in leaves of 'Huangjinya'. Overall, the light-induced albino cultivar 'Huangjinya' was susceptible to E. onukii while 'Fudingdabai' was resistant.

The seven-spotted ladybird beetle, Coccinella septempunctata L., as a dominant predator of aphids, has played a crucial role in integrated pest management (IPM) strategies in agricultural ecosystems. To study the risk of insecticides to C. septempunctata, the neonicotinoid clothianidin was selected for evaluation of its influence on C. septempunctata at lethal and sublethal doses. The LR50 (application rate causing 50% mortality) in the exposed larvae decreased from 19.94 to 5.91 g a.i. ha−1, and the daily HQ (hazard quotient) values increased from 3.00 to 10.15, indicating potential intoxication risks. We also determined NOERs (No Observed Effect application Rates) of clothianidin on the total developmental time (10 g a.i. ha−1), survival (2.5 g a.i. ha−1) and pupation (5 g a.i. ha−1). Moreover, clothianidin at a NOER of 2.5 g a.i. ha−1 did not profoundly affect adult emergence, fecundity or egg hatchability. The total effect (E) assessment also showed that clothianidin at 2.5 g a.i. ha−1 was slightly harmful to C. septempunctata. These results suggested that clothianidin would impair C. septempunctata when applied at over 2.5 g a.i. ha−1 in the field. Conservation of this biological control agent in agricultural ecosystems thus requires further measures to decrease the applied dosages of clothianidin.

Bradysia odoriphaga (Diptera: Sciaridae) is the major pest affecting Chinese chive production. Chlorfenapyr is a halogenated pyrrole-based pro-insecticide that is currently used to control insects and mites on a variety of crops. In the present study, fourth-instar larvae of B. odoriphaga were exposed to chlorfenapyr at LC1, LC20 and LC50 concentrations. The developmental duration of the treated larvae was not significantly different, but fecundity was significantly increased in the LC1 and LC20 treatment groups compared with the control group. The population parameters of the LC1 treatment group were increased significantly, whereas those of the LC50 treatment group were reduced significantly compared with the control. The food consumption by larvae and pupal weight were significantly increased under the LC1 treatment and decreased under the LC50 treatment compared with the control. Moreover, chlorfenapyr decreased the lipid, carbohydrate and trehalose contents significantly, whereas the total protein content was increased compared with the control. Additionally, the activities of protease, lipase and trehalase were significantly decreased. Chlorfenapyr treatment for 24 h also induced the activities of glutathione S-transferase (GST), carboxylesterase (CarE) and O-demethylation. The results of this study suggest that low lethal concentrations of chlorfenapyr can affect oviposition, population development, the activities of digestion and detoxification enzymes, and nutrient accumulation in B. odoriphaga. This study provides valuable information for the assessment and rational application of chlorfenapyr for effective control of this pest.

Neonicotinoid insecticides (NIs) have recently been recognized as co-factors in the decline of honeybee colonies because most neonicotinoids are systemic and can transfer into the pollen and nectar of many pollinated crops. In this study, we collected pollen, nectar and leaves from a cotton crop treated with imidacloprid and thiamethoxam to measure the residue levels of these two NIs at different application doses during the flowering period. Then, the residual data were used to assess the risk posed by the systemic insecticides to honeybees following mandated methods published by the European Food Safety Authority (EFSA), and a highly toxic risk to honeybees was highlighted. Imidacloprid was found in both pollen and nectar samples, whereas thiamethoxam was found in 90% of pollen samples and over 60% of nectar samples. Analysis of the pollen and nectar revealed residual amounts of imidacloprid ranging from 1.61 to 64.58 ng g−1 in the pollen and from not detected (ND) to 1.769 ng g−1 in the nectar. By comparison, the thiamethoxam concentrations in pollen and nectar ranged from ND to 14.521 ng g−1 and from ND to 4.285 ng g−1, respectively. The results of this study provide information on the transfer of two NIs from seed treatment to areas of the plant and provides an understanding of the potential exposure of the bee and other pollinators to systemic insecticides.

Recently, due to the decreased usage of broad-spectrum insecticides in transgenic Bt cotton in China, Apolygus lucorum (Meyer-Dur) (Hemiptera: Miridae) has emerged as a major pest of cotton and other agricultural crops. A glass vial bioassay method was used to evaluate the resistance in the Shandong populations of A. lucorum to seven commonly used insecticides during 2009–2014. For organophosphate insecticides, there was no resistance to malathion in most of the collected populations, and resistance ratios were 1.2–5.6-fold for chlorpyrifos in comparison to a susceptible Juye strain. For pyrethroid insecticides, the resistance of three populations (Juye, Huimin and Xiajin) showed an upward tendency during the six studied years, and the resistance levels were 2.0–19.5-fold for bifenthrin and 1.1–8.2-fold for lambda-cyhalothrin, but the efficiency of bifenthrin remained high because its LC 50 value was very low (LC 50 2 ) compared to the LC 50 values of other insecticides. For carbamate insecticides, the resistance ratios ranged from 1.6 to 19.0-fold for methomyl and 1.3–5.5-fold for carbosulfan. For phenylpyrazole insecticides, there was moderate resistance to fipronil (up to 31.3-fold). The resistances of A. lucorum to insecticides have developed slowly in Shandong, except the resistance of the Juye population to fipronil. Therefore, malathion, chlorpyrifos, bifenthrin and carbosulfan can still be employed in integrated pest management (IPM) programs supplemented with physical and biological control methods.

The mirid bug Apolygus lucorum (Meyer-Dür) has become a major pest in cotton fields and has led to significant yield losses due to the widespread use of transgenic Bt cotton in China. Eight neonicotinoid seed treatments were investigated to determine their effects on the management of A. lucorum in cotton fields. All neonicotinoid seed treatments reduced the cotton damage caused by A. lucorum, and nitenpyram at the rate of 4 g/kg seed showed the most favorable efficacy in suppressing A. lucorum populations throughout the cotton seedling stage. The neonicotinoid seed treatments had no effect on the emergence rate of cotton seeds. Although the neonicotinoid seed treatments were not significantly different from the spray treatments in the cotton yield, the seed treatments reduced the need for three pesticide applications and showed a tremendous advantage in labor costs throughout the cotton seedling stage. Overall, the neonicotinoid seed treatments, particularly the nitenpyram seed treatment, can provide effective protection and should play an important role in the management of early season A. lucorum in Bt cotton fields.

We investigated the effect of the SHAM treatment of tea plants on their induced defense on a tea geometrid (TG), Ectropis obliqua Prout. Treatment of tea leaves with SHAM reduced the performance of TG and TG-elicited level of the lipoxygenase gene CsiLOX1 and the putative allene oxide synthase gene CsiAOS1. The release of wound-induced green leaf volatiles (GLVs) and the expression of the hydroperoxide lyase (HPL) gene CsiHPL1 were also reduced by SHAM treatment. The negative effect of SHAM dramatically reduced the total hebivore-induced plant volatiles (HIPVs) and the attractiveness to the parasitoid wasp Apanteles sp. These results indicated that SHAM may negatively mediate tea defense response against TG by modulating the wound-induced emission of GLVs, the expression of genes involved in oxylipin pathway, and the emission of other HIPV compounds that mediate direct and indirect defenses.

BACKGROUND A plant-based ‘push-pull’ strategy for Ectropis obliqua (Prout) (Lepidoptera: Geometridae) is being developed using semiochemicals in the volatiles of Rosmarinus officinalis (Lamiaceae). The aim of this study was to identify and quantify the bioactive components within R. officinalis by gas chromatography–electroantennographic detection (GC-EAD) and gas chromatography–mass spectrometry (GC-MS), and to test the antennal and behavioural responses of E. obliqua to these chemicals. The emission dynamics of bioactive chemicals was also monitored. RESULTS GC-EAD experiments indicated that E. obliqua antennae responded to the following volatile compounds from R. officinalis: myrcene, α-terpinene, γ-terpinene, linalool, cis-verbenol, camphor, α-terpineol and verbenone, which were the minor constituents. Based on the dose-dependent antennal and behavioural responses of E. obliqua to these bioactive compounds, myrcene, γ-terpinene, linalool, cis-verbenol, camphor and verbenone were found to play a key role in repelling the moths, and the mixture that included all eight compounds was significantly more effective. The maximum emissions of these semiochemicals occurred at nightfall. CONCLUSIONS The specifically bioactive compounds in R. officinalis volatiles are responsible for repelling E. obliqua adults. Results indicate that R. officinalis should be considered as a potential behaviour-modifying stimulus for ‘push’ components when developing ‘push-pull’ strategies for control of E. obliqua using semiochemicals. © 2014 Society of Chemical Industry

To better understand the application prospect of cyantraniliprole against the Asian corn borer, Ostrinia furnacalis , a diet-incorporation bioassay was adopted to determine the toxicity of cyantraniliprole against the fourth instar of O. furnacalis . Moreover, other experiments were conducted to examine effects of sublethal levels of cyantraniliprole on larval development, nutrient utilization, and reproduction. In this study, cyantraniliprole showed a high toxicity to fourth-instar larvae of O. furnacalis at dosages of 0.05 μg/g (LC5), 0.11 μg/g (LC20), 0.20 μg/g (LC40), and 0.26 μg/g (LC50) administered through artificial diet. At three sublethal dosages, cyantraniliprole inhibited larval feeding processes, decreased the relative growth rate, the relative consumption rate, the efficiency of food ingestion, and the efficiency of food digestion, as well as decreased the contents of nutrients such as proteins, lipids, and carbohydrates. All these effects go against to the normal growth of O. furnacalis , including reductions in larval and pupal weight, the extension of the larval and pupal period, the prolongation of the adult preoviposition period, total preoviposition period, and mean generation time, and the reduction of adult longevity, oviposition period, and eggs laid by female adults. Together, these changes resulted in the reduction of the intrinsic rate of increase . Hence, even at sublethal concentrations, cyantraniliprole can affect population dynamics by reducing the survival rate, fecundity, and population parameters. This result provides useful information for developing control strategies for O. furnacalis.

The effects of eight neonicotinoid seed treatments against the cotton aphid Aphis gossypii and its natural enemies in Bt cotton fields were evaluated, and the concentrations of these neonicotinoids in cotton leaves and soil were also investigated. The results showed that all neonicotinoid seed treatments efficiently reduced A. gossypii populations throughout the cotton seedling stage. The percentages of curly leaf plants in all of the neonicotinoid seed treatments were below the threshold for economic loss. Among the eight tested neonicotinoid seed treatments, nitenpyram, dinotefuran, and thiamethoxam showed high control efficiency against A. gossypii. Residues of the three neonicotinoids were higher than those of other neonicotinoids in cotton leaves. Moreover, residues of dinotefuran and nitenpyram remained at low levels in the soil. However, the abundance of natural enemies in the cotton field was to some extent influenced by neonicotinoid seed treatments. Therefore, neonicotinoids nitenpyram, dinotefuran, and thiamethoxam used as seed treatment can provide effective protection that should play an important role in the management of early-season A. gossypii in Bt cotton fields; however, the risks of neonicotinoids to the environment should also be considered.

Volatile organic compounds derived from non-host plants, Ocimum basilicum, Rosmarinus officinalis, Corymbia citriodora, and Ruta graveolens, can be used to mask host plant odors, and are repellent to the tea geometrid, Ectropis obliqua. Volatile compounds were collected by headspace absorption, and the components were identified and quantified by using gas chromatography/mass spectrometry. The responses of antennae of female E. obliqua to the compounds were evaluated with gas chromatography/electroantennography detection. Qualitative and quantitative differences were found among the four odor profiles. Consistent electroantennographic activity was obtained for eight of the volatiles from the four plants: β-myrcene, α-terpinene, γ-terpinene, linalool, cis-verbenol, camphor, α-terpineol, and verbenone. In a Y-tube bioassay, six chemicals, β-myrcene, γ-terpinene, (R)-(-)-linalool, (S)-(-)-cis-verbenol, (R)-(+)-camphor, and (S)-(-)-verbenone, were the main compounds responsible for repelling E. obliqua. An eight-component mixture including all of the bioactive compounds (in a ratio of 13:2:13:8:1:24:6:17) from R. officinalis was significantly more effective at repelling the moths than any single compound or a mixture of equal amounts of the eight compounds. Field results demonstrated that intercropping tea plants with R. officinalis effectively suppressed E. obliqua infestations in a tea plantation. Our findings suggests that odor blends of R. officinalis play a role in disturbing host orientation behavior, and in repelling E. obliqua adults, and that R. officinalis should be considered when developing "push-pull" strategies aimed at optimizing the control of E. obliqua with semiochemicals.

Hydroperoxide lyases (HPLs) play important roles in modulating plant defense by regulating the release of green leaf volatiles (GLVs) and the jasmonic acid (JA) pathway. CsiHPL1—a chloroplast-localized tea gene that encodes HPL—was previously cloned and predicted to be a regulator of plant defense responses. CsiHPL1 was expressed constitutively in transgenic tomato (Solanum lycopersicum) plants to define its function in plant defense. CsiHPL1 overexpression caused tomato to release more constitutive and wound-induced GLVs [including (Z)-hexenal and (Z)-3-hexen-1-ol]. CsiHPL1 transgenic lines also exhibited lower levels of resistance to the larva of the tomato-chewing herbivore Prodenia litura (Fabricius) but enhanced resistance to the necrotrophic fungus Alternaria alternata f. sp. lycopersici (AAL). Furthermore, transgenic lines exhibited decreased expression levels of JA-related genes (SlAOS and SlPI-II) induced by P. litura and AAL infection. We thus concluded that constitutive expression of CsiHPL1 can regulate tomato resistance to P. litura and AAL by modulating GLV release and JA gene expression. Application of these results will be helpful in controlling plant defenses against herbivore attack and fungal disease.

Benzothiazole, a microbial secondary metabolite, has been demonstrated to possess fumigant activity against Sclerotinia sclerotiorum, Ditylenchus destructor and Bradysia odoriphaga. However, to facilitate the development of novel microbial pesticides, the mode of action of benzothiazole needs to be elucidated. Here, we employed iTRAQ-based quantitative proteomics analysis to investigate the effects of benzothiazole on the proteomic expression of B. odoriphaga. In response to benzothiazole, 92 of 863 identified proteins in B. odoriphaga exhibited altered levels of expression, among which 14 proteins were related to the action mechanism of benzothiazole, 11 proteins were involved in stress responses, and 67 proteins were associated with the adaptation of B. odoriphaga to benzothiazole. Further bioinformatics analysis indicated that the reduction in energy metabolism, inhibition of the detoxification process and interference with DNA and RNA synthesis were potentially associated with the mode of action of benzothiazole. The myosin heavy chain, succinyl-CoA synthetase and Ca+-transporting ATPase proteins may be related to the stress response. Increased expression of proteins involved in carbohydrate metabolism, energy production and conversion pathways was responsible for the adaptive response of B. odoriphaga. The results of this study provide novel insight into the molecular mechanisms of benzothiazole at a large-scale translation level and will facilitate the elucidation of the mechanism of action of benzothiazole.

To better understand the sublethal effects of cyantraniliprole on the black cutworm Agrotis ipsilon (Lepidoptera: Noctuidae), several studies were carried out to investigate sublethal effects on development stages, population parameters, feeding indices and nutrient content of A. ipsilon. The result of a bioassay showed that cyantraniliprole had high toxicity against A. ipsilon fourth-instar larvae with an LC50 of 0.354 μg.g−1 using an artificial diet. Compared with controls, sublethal doses of cyantraniliprole at LC5, LC20 and LC40 levels prolonged larval and pupal duration and extended mean generation time and total preovipositional period. In addition, survival rate, reproductive value, intrinsic and finite rates of increase and net reproduction rate declined significantly. Meanwhile, cyantraniliprole had markedly antifeedant effects; decreased the relative growth rate (RGR), the relative consumption rate (RCR), the efficiency of conversion of ingested food (ECI), the efficiency of conversion of digested food (ECD); and increased the approximate digestibility (AD) significantly. This phenomenon contributed to the decrease of nutrient contents, including lipids, protein and carbohydrates, to the point that insufficient energy was available for normal growth. Therefore, sublethal concentrations of cyantraniliprole decreased growth speed and reduced population reproduction of A. ipsilon. This result provides information useful in integrated pest management (IPM) programs for A. ipsilon.