Chronic Sublethal Effects of Cantharidin on the Diamondback Moth Plutella xylostella (Lepidoptera: Plutellidae)

The diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), is a major pest of cruciferous vegetables worldwide. Cantharidin, a natural toxin isolated from blister beetles, has been reported to be toxic to P. xylostella. However, little is known on the chronic sublethal effects of cantharidin on this species. In this study, we assessed the changes of susceptibility, development, reproduction and other demographic parameters in both the selected P. xylostella strain (Sub, selected by LC₂₅ cantharidin for consecutive 12 generations) and the revertant strain (SubR, derived from the Sub strain without being exposed to cantharidin for 12 generations). Results revealed that the two strains maintained a relatively high-level susceptibility to cantharidin. Severe adverse effects on the population dynamics and fitness in Sub strain were observed. In addition, repeated exposure of P. xylostella to sublethal concentration of cantharidin resulted in negative effects on adult performance and deformities in adults. Although morphologically normal for individuals, the SubR strain exhibited a disadvantage in population growth rate. Our results showed that sublethal concentration of cantharidin exhibited severe negative effects on population growth for longtime. These findings would be useful for assessing the potential effects and risk of cantharidin on P. xylostella and for developing effective integrated pest management.     

Effects of bistrifluron resistance on the biological traits of Spodoptera litura (Fab.) (Noctuidae: Lepidoptera)

Spodoptera litura is one of the major insect pests of vegetables in Sichuan, China, and it has developed serious resistance to many traditional chemical insecticides. In this present study, S. litura individuals collected from five regions in Sichuan in 2017, which were detected the resistance to bistrifluron. We found that the resistance ratios (RRs) bistrifluron were in the ranges of 15.9- to 77.7-fold, respectively, compared with a laboratory susceptible (Lab-HN) strain. To elucidate the effect of bistrifluron on the life history parameters of S. litura, we established the bistrifluron-susceptible (Bis-UNSEL) and bistrifluron-resistant (Bis-SEL) strains based on the DY field population with the highest RR of 77.7-fold among the all field populations to bistrifluron compared with a laboratory Lab-HN strain. The results show that the Bis-SEL strain developed a 113.8-fold RR while that of the Bis-UNSEL strain was almost equal to that of the Lab-HN strain (with overlapping confidence intervals (CI) of their LC₅₀ values, P < 0.05). Meanwhile, the life span of the egg and pupa stage of the Bis-UNSEL strain was prolonged, and the strain also showed shorter adult duration and lower fecundity. Demographic characteristics, such as the intrinsic rate of increase (r), finite rate of increase (λ) and net reproductive rate (R₀) in the Bis-SEL strain were significantly higher than the Bis-UNSEL strain, whereas the mean generation time (T) and gross reproduction rate (GRR) were lower. The results clearly showed that the developing resistance of bistriflueon on S. litura promoted its population growth. Therefore, the present study could provide useful informations for determining potential management methods to prevent the development of bistrifluron resistance in S. litura.

     

Sublethal and transgenerational effects of insecticides in developing Trichogramma galloi (Hymenoptera: Trichogrammatidae)

This study assessed the transgenerational effects of insecticides in developing Trichogramma galloi (Hymenoptera: Trichogrammatidae). Laboratory bioassays were performed in which five insecticides were sprayed on egg-larval, pre-pupal and pupal stages of the parasitoid. The interaction between insecticides and development stages of the parasitoid was not significant for the rate of F0 emergence. All insecticides significantly reduced the emergence of wasps, with the lowest emergence observed when they were applied to the pupal stage. For the sex ratio, only spinosad applied to the pre-pupal stage and triflumuron applied on the egg-larval and pre-pupal stages did not differ from the controls. Triflumuron applied to pre-pupae did not lead to any difference in the parasitism rate of the treated generation (F0) when compared to the control. There were no significant differences among survival curves for females of F0 when all insecticides were sprayed on the egg-larval stage. Both concentrations of lambda-cyhalothrin + thiamethoxam reduced female pre-pupal survival, and all treatments reduced female pupal survival. In addition, we observed a transgenerational effect of the insecticides on emergence and sex ratio of next generation (F1). Lambda-cyhalothrin + thiamethoxam (Min) applied to the pre-pupae and pupae, the maximum rate of the same insecticides applied to the egg-larvae and pre-pupae, and spinosad applied to pre-pupae all significantly reduced the adults emergence of T. galloi F1 generation. Only triflumuron did not alter the F1 sex ratio. These bioassays provide a basis for better understanding the effects of insecticide use on beneficial parasitoids.     

Assessing the Single and Combined Toxicity of Chlorantraniliprole and Bacillus thuringiensis (GO33A) against Four Selected Strains of Plutella xylostella (Lepidoptera: Plutellidae), and a Gene Expression Analysis

Concerns about resistance development to conventional insecticides in diamondback moth (DBM) Plutella xylostella (L.), the most destructive pest of Brassica vegetables, have stimulated interest in alternative pest management strategies. The toxicity of Bacillus thuringiensis subsp. aizawai (Bt GO33A) combined with chlorantraniliprole (Chl) has not been documented. Here, we examined single and combined toxicity of chlorantraniliprole and Bt to assess the levels of resistance in four DBM strains. Additionally, enzyme activities were tested in field-original highly resistant (FOH-DBM), Bt-resistant (Bt-DBM), chlorantraniliprole-resistant (CL-DBM), and Bt + chlorantraniliprole-resistant (BtC-DBM) strains. The Bt product had the highest toxicity to all four DBM strains followed by the mixture of insecticides (Bt + Chl) and chlorantraniliprole. Synergism between Bt and chlorantraniliprole was observed; the combination of Bt + (Bt + Chl) (1:1, LC₅₀:LC₅₀) was the most toxic, showing a synergistic effect against all four DBM strains with a poison ratio of 1.35, 1.29, 1.27, and 1.25. Glutathione S-transferase (GST) and carboxyl-esterase (CarE) activities showed positive correlations with chlorantraniliprole resistance, but no correlation was observed with resistance to Bt and Bt + Chl insecticides. Expression of genes coding for PxGST, CarE, AChE, and MFO using qRT-PCR showed that the PxGST and MFO were significantly overexpressed in Bt-DBM. However, AChE and CarE showed no difference in the four DBM strains. Mixtures of Bt with chlorantraniliprole exhibited synergistic effects and may aid the design of new combinations of pesticides to delay resistance in DBM strains substantially.     

Sublethal and transgenerational effects of sulfoxaflor on the biological traits of the cotton aphid, <Emphasis Type="Italic">Aphis gossypii</Emphasis> Glover (Hemiptera: Aphididae)

Sulfoxaflor is a novel insecticide belonging to sulfoximine chemical class that can be used to control sap-feeding insects, notably Aphis gossypii Glover. In addition to its acute toxicity, it is also important to consider the possible sublethal effects when establishing a comprehensive understanding of the toxicity of a new insecticide. We assessed the effects of a low lethal concentration (LC₂₅) of sulfoxaflor on biological parameters of A. gossypii adults (F0) and subsequent transgenerational effects, i.e., on the progeny (F1 generation). The data were analyzed using an age-stage life table procedure. The results showed that the longevity and fecundity were not significantly affected by the LC₂₅ of sulfoxaflor in the F0 or F1 generations. In addition, no significant differences were observed on the developmental time of each instar, the adult pre-oviposition period, and on the longevity of F1 individuals. However, the duration of their pre-adult stage and total pre-oviposition period, as well as their mean generation time were significantly increased. These observed effects affected aphid demographic traits; the survival rate, the intrinsic rate of increase (r _i ), the finite rate of increase (λ), the net reproductive rate (R₀), and the gross reproduction rate (GRR) of the F1 individuals (i.e., from F0 mothers) were significantly lower compared to the control. Our results showed that sublethal effects of sulfoxaflor significantly slowed down A. gossypii population growth; they indicated that effects of sulfoxaflor might be increased (beyond lethal effect) through sublethal effects when concentrations decreased in sulfoxaflor-treated areas after initial application in field.     

Insecticidal activities of Parthenium hysterophorus L. extract and parthenin against diamondback moth,Plutella xylostella (L.) and aphid,Aphis craccivora Koch

Insecticidal activities of Parthenium hysterophorus L. (PH) studied against Plutella xylostella the major insect pest of cruciferous crops and Aphis craccivora Koch on legume crops. Results showed that PH extract found promising toxicity (LC_50?=?1140.68?mg L^?1) to larvae of P. xylostella after 96?h of treatment as compared to parthenin (LC_50?=?1709.42?mg L^?1). Parthenin also showed moderate repellent activity to P. xylostella (43.33?±?4.18%). However, parthenin is more effective against A. craccivora (LC_50?=?839?mg L^?1) than PH extract (LC_50?=?947.87?mg L^?1). Based on field bio-efficacy studies, PH extract can be recommended for the management of target pests.     

Sublethal effects of atrazine on embryo-larval development of Rhinella arenarum (Anura: Bufonidae)

Atrazine (ATR), one of the most widely used herbicides in the world, affects not only target organisms but also the biota in general. Here, the teratogenic and neurotoxic effects of ATR on Rhinella arenarum (South American toad) embryos, and larvae were evaluated by means of standardized bioassays during acute and chronic exposures. The herbicide had a significant incidence of malformations, with a Teratogenic Index (TI) of 3.28. The main effects were delayed development, reduced body size, microcephaly, axial flexures, wavy tail and edema. In addition, delayed development, reduced development of forelimbs, and edema were recorded at metamorphosis stages. Scanning electron microscopy allowed observing different degrees of cellular dissociation and persistent cilliar cells in specific regions like the adhesive structure and tail fin. Results obtained by ATR 24 h pulse exposures at six developmental stages pointed out blastula as the most susceptible developmental stage both for immediate and delayed adverse effects. A noteworthy recovery capacity from acute toxic effects was recorded from the neural plate stage onwards. Regarding neurotoxic effects, abnormal, and erratic swimming and spasmodic contractions were recorded. Both the teratogenic and neurotoxic effects reported in this study demonstrate the importance of evaluating sublethal effects in non-target organisms as they could imply reduced fitness of individuals and eventually a population decline. The Hazard Quotients (HQ) for ATR ranged from 0.14 to 10.80, and the fact that some of these values are above USEPA’s level of concern indicate that ATR is likely a risk to R. arenarum.     

Chalcones as promising pesticidal agents against diamondback moth (Plutella xylostella): microwave-assisted synthesis and structure–activity relationship

A series of chalcones (A–CH=CH–CO–B) were synthesized under microwave irradiation, and for the first time their pesticidal activity against diamondback moth (Plutella xylostella) was evaluated to identify the promising lead structures. The structure–activity relationship (SAR) analysis revealed that electron-withdrawing substituents on ring A of chalcone provided good pesticidal agents, whereas, ring B can bear either electron-withdrawing or electron-releasing substituents. Moreover, compound 22 having para-Cl substitution on ring A as well on ring B showed maximum activity with LC₅₀ value of 170.24 μg mL⁻¹.     

In vivo effects of deoxynivalenol (DON) on innate immune responses of carp (Cyprinus carpio L.)

Deoxynivalenol (DON) is one of the most important members of Fusarium toxins since it often can be found in relevant concentrations in animal feeds. The effects of this group of toxins on fish are mostly unknown. The present study shows results from a feeding trial with carp (Cyprinus carpio L.) using three different concentrations of DON (352 μg kg⁻¹, 619 μg kg⁻¹, and 953 μg kg⁻¹ final feed, respectively) which are comparable to levels found in commercial fish feeds. Effects on growth and mass of fish were not observed during this 6 weeks lasting experiment. Only marginal DON concentrations were found in muscle and plasma samples. Blood parameters were not influenced although smaller erythrocytes occurred in fish treated with 352 μg kg⁻¹ DON. Analysis of antioxidative enzymes in erythrocytes showed increased superoxid dismutase and catalase activities in fish fed the low-dose feed. Immunosuppressive effects of DON were confirmed whereby cytotoxic effects on immune cells only partly explained the impairment of innate immune responses. Exact polarization of the immune system into pro-inflammatory or anti-inflammatory responses due to DON exposure should be clarified in further experiments, especially since the current results raise concern about impaired immune function in fish raised in aquaculture.     

Volatile,non-volatile composition and insecticidal activity of Eupatorium adenophorum Spreng against diamondback moth,Plutella xylostella (L.), and aphid,Aphis craccivora Koch

Essential oil (EO) from aerial parts of Eupatorium adenophorum Spreng was extracted by steam distillation and characterized by Gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). α-epi-cadinenol (16.63%), O-cymene (13.54%), bornyl acetate (7.70%), β-phellandrene (7.46%), and σ-2-carene (5.77%) were the major terpenoids. The EO showed promising toxicity (median lethal concentration, LC₅₀?=?3176.54?mg?L^?1) and repellent activity (median repellent concentration, RC₅₀?=?2070.99?mg L^?1) to larvae of Plutella xylostella within 24?h. Among fractions, hexane fraction was more effective to P. xylostella (LC₅₀?=?5056.74?mg L^?1), whereas methanol fraction to Aphis craccivora (LC₅₀?=?1175.83?mg L^?1).     

Transgenerational sublethal effects of abamectin and pyridaben on demographic traits of Phytonemus pallidus (Banks) (Acari: Tarsonemidae)

In addition to determining the lethal effects, identifying sublethal effects of a pesticide is crucial to understanding the total impact a pesticide may have on a pest population. We determined the sublethal effects the two pesticides, abamectin and pyridaben, have on the cyclamen mite, Phytonemus pallidus (Banks) (Acari: Tarsonemidae)—a major pest of strawberry. Demographic traits of the P. pallidus progeny (F1 generation) produced by parents (F0 generation) treated with a low lethal concentration (LC₁₅) of abamectin and pyridaben were assessed using the age-stage, two-sex life table theory. The total longevity of the F1 generation (males = 10.78 days; female = 14.35 days) was the shortest in the progeny of the abamectin treated parents, differing significantly from the progeny of mites treated with pyridaben (males = 11.50 days, females = 15.63 days), and the control population (males = 13.50 days, females = 17.81 days). The intrinsic rates of increase (r) and the finite rates of increase (λ) of the progeny of abamectin (r = 0.0854 day⁻¹, λ = 1.0891 day⁻¹) and pyridaben (r = 0.0951 day⁻¹, λ = 1.0997 day⁻¹) treated parents were significantly lower than in the control mites (r = 0.1455 day⁻¹, λ = 1.1567 day⁻¹). The lowest fecundity (5.35 eggs/female), occurred in F1 female offspring of parents treated with LC₁₅ concentrations of abamectin, which was significantly lower than in the pyridaben (6.11 eggs/female) and control treatments (11.45 eggs/female). Transgenerational sublethal effects of abamectin and pyridaben in P. pallidus can be effectively used to for optimizing IPM programs against this pest on strawberries.

     

Phytotoxic and genotoxic effects of ZnO nanoparticles on garlic (Allium sativum L.): a morphological study

The effects of zinc oxide nanoparticles (ZnO NPs) on the root growth, root apical meristem mitosis and mitotic aberrations of garlic (Allium sativum L.) were investigated. ZnO NPs caused a concentration-dependent inhibition of root length. When treated with 50 mg/L ZnO NPs for 24 h, the root growth of garlic was completely blocked. The 50% inhibitory concentration (IC(50)) was estimated to be 15 mg/L. The mitosis index was also decreased in a concentration- and time-dependent manner. ZnO NPs also induced several kinds of mitotic aberrations, mainly consisted of chromosome stickiness, bridges, breakages and laggings. The total percentage of abnormal cells increased with the increase of ZnO NPs concentration and the prolongation of treatment time. The investigation provided new information for the possible genotoxic effects of ZnO NPs on plants.     

Chemical composition of essential oil and oleoresins of Zingiber officinale and toxicity of extracts/essential oil against diamondback moth (Plutella xylostella)

Abstract

Essential oil (EO) of ginger and oleoresins isolated from extraction solvents by GC–MS. Zingiberene was the major constituent in all the samples, and ethanol could extract the maximum quantity (21.2%) from the dried de-oiled cake (EDD) followed by EO (20.3%) as compared to oleoresins. Hydro-distilled EO contains higher oxygenated monoterpenes (22.4%) than oleoresins. EDD showed more toxicity to larvae of Plutella xylostella (LC₅₀?=?4957.9?mg L^?1) after 96?h and was followed by EDW (LC₅₀?=?5067.6?mg L^?1) and EF (LC₅₀?=?6631.2?mg L^?1). EO also showed promising efficacy (LC₅₀?=?5875.9?mg L^?1) and repellency (97.1%) against P. xylostella.     

厚藤Ipomoep Pes-Caprae(L.) Sweet的化学成分研究(Ⅰ)

目的从厚藤(Ipomoea Pes-Caprae(L.)Sweet)的乙酸乙酯提取物中分离到7个化合物.方法采用柱层析技术、经理化常数和波谱分析进行结构鉴定.结果它们分别是β-香树素(1)、12-ursen-3-ol(2)、β-谷甾醇(3)、豆甾醇(4)、α-菠甾醇(5)、异莨菪亭(6)和七叶内酯(7).结论其中异莨菪亭和七叶内酯为首次从该植物中分离得到.     

Medetomidine as a candidate antifoulant: sublethal effects on juvenile turbot (Psetta maxima L.)

Medetomidine is proposed as a candidate antifouling compound proven effective against barnacles. It is routinely used as a sedative in veterinary medicine. It is therefore important to also investigate possible adverse effects on non-target organisms. Thus, sublethal effects on two different ages of juvenile turbot (Psetta maxima) exposed to a wide concentration range of medetomidine (0.063-420nM) were assessed after exposure under semistatic as well as flow-through conditions, for a maximum of 96h. Effects on respiration frequency and amount of oxygen consumed were assessed, as well as the ability of turbot to adapt to a dark background. A significant decrease was seen both in respiration frequency with a lowest observed effect concentration (LOEC) of 2.1nM as well as in amount of oxygen consumed (LOEC=420nM) and colour adaptation (LOEC=4.2nM). Colour adaptation was also evaluated in a short exposure experiment, 1h, where significant effects were observed (LOEC=2.1nM). Reversibility, when fish were incubated in clean seawater following exposure, was seen for all observed effects. Ecological relevance of the observed effects is discussed.     

Physiological effects of magnetite (Fe3O4) nanoparticles on perennial ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta) plants

Abstract

To date, knowledge gaps and associated uncertainties remain unaddressed on the effects of nanoparticles (NPs) on plants. This study was focused on revealing some of the physiological effects of magnetite (Fe₃O₄) NPs on perennial ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta cv. white cushaw) plants under hydroponic conditions. This study for the first time reports that Fe₃O₄ NPs often induced more oxidative stress than Fe₃O₄ bulk particles in the ryegrass and pumpkin roots and shoots as indicated by significantly increased: (i) superoxide dismutase and catalase enzyme activities, and (ii) lipid peroxidation. However, tested Fe₃O₄ NPs appear unable to be translocated in the ryegrass and pumpkin plants. This was supported by the following data: (i) No magnetization was detected in the shoots of either plant treated with 30, 100 and 500 mg l^?1 Fe₃O₄ NPs; (ii) Fe K-edge X-ray absorption spectroscopic study confirmed that the coordination environment of Fe in these plant shoots was similar to that of Fe-citrate complexes, but not to that of Fe₃O₄ NPs; and (iii) total Fe content in the ryegrass and pumpkin shoots treated with Fe₃O₄ NPs was not significantly increased compared to that in the control shoots.     

Physiological effects of magnetite (Fe3O4) nanoparticles on perennial ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta) plants

To date, knowledge gaps and associated uncertainties remain unaddressed on the effects of nanoparticles (NPs) on plants. This study was focused on revealing some of the physiological effects of magnetite (Fe(3)O(4)) NPs on perennial ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta cv. white cushaw) plants under hydroponic conditions. This study for the first time reports that Fe(3)O(4) NPs often induced more oxidative stress than Fe(3)O(4) bulk particles in the ryegrass and pumpkin roots and shoots as indicated by significantly increased: (i) superoxide dismutase and catalase enzyme activities, and (ii) lipid peroxidation. However, tested Fe(3)O(4) NPs appear unable to be translocated in the ryegrass and pumpkin plants. This was supported by the following data: (i) No magnetization was detected in the shoots of either plant treated with 30, 100 and 500 mg l(-1) Fe(3)O(4) NPs; (ii) Fe K-edge X-ray absorption spectroscopic study confirmed that the coordination environment of Fe in these plant shoots was similar to that of Fe-citrate complexes, but not to that of Fe(3)O(4) NPs; and (iii) total Fe content in the ryegrass and pumpkin shoots treated with Fe(3)O(4) NPs was not significantly increased compared to that in the control shoots.