Bioassay Experiments Research Articles

Overexpression of UDP-glucuronosyltransferase and cytochrome P450 enzymes confers resistance to sulfoxaflor in field populations of the aphid, Myzus persicae

The green peach aphid, Myzus persicae, is a highly damaging, globally distributed crop pest that has evolved multiple resistance to numerous insecticides. It is thus imperative that insecticides that are not strongly compromised by pre-existing resistance are carefully managed to maximise their effective life span. Sulfoxaflor is a sulfoximine insecticide that retains efficacy against M. persicae clones that exhibit resistance to older insecticides. In the current study we monitored the efficacy of sulfoxaflor against M. persicae populations collected in Western Australia, following reports of control failures in this region. We identified clones with low (4-23-fold across multiple independent bioassay experiments), but significant, levels of resistance to sulfoxaflor compared with a reference susceptible clone. Furthermore, we demonstrate that sulfoxaflor resistance can persist after many months of culturing in the laboratory in the absence of insecticide exposure. Resistance was not conferred by known mechanisms of resistance to neonicotinoid insecticides, that act on the same target-site as sulfoxaflor, i.e. the R81T mutation or overexpresssion of the P450 gene CYP6CY3. Rather, transcriptome profiling of multiple resistant and susceptible clones identified the P450 CYP380C40 and the UDP-glucuronosyltransferase UGT344P2 as highly overexpressed (21-76-fold and 6-33-fold respectively) in the resistant clones. Transgenic expression of these genes demonstrated that they confer, low, but significant, levels of resistance to sulfoxaflor in vivo. Taken together, our data reveal the presence of low-level resistance to sulfoxaflor in M. persicae populations in Australia and uncover two novel mechanisms conferring resistance to this compound. The findings and tools generated in this study provide a platform for the development of strategies that aim to slow, prevent or overcome the evolution of more potent resistance to sulfoxaflor.

Springtime phytoplankton responses to light and iron availability along the western Antarctic Peninsula

AbstractLight and iron availability are intertwined in controlling Southern Ocean primary production because several photosynthetic proteins require iron. Changes in light and iron availability can also affect phytoplankton species composition, which impacts nutrient cycling, carbon drawdown, and food web structure. To investigate the interactive effects of light and iron on phytoplankton growth, photosynthesis, photoacclimation strategy, micronutrient stress‐induced protein expression, and species composition, we conducted five bioassay experiments during spring in waters along the western Antarctic Peninsula with four treatments: low light (LL) or high light (HL) combined with or without iron addition. This region has rarely been studied in spring. We found that light limits growth while iron does not, despite overall low iron concentrations. Our results demonstrate that phytoplankton were LL acclimated in situ but photosynthetically optimized for higher light than they were experiencing, likely due to a highly dynamic light regime. Expression patterns of micronutrient stress‐induced proteins were consistent with iron stress in off‐shelf regions, but remarkably this iron stress did not result in lower carbon fixation and growth rates. Notably, manganese drawdown was highest under elevated light, suggesting a possible role in managing HL, although high flavodoxin expression indicated that Phaeocystis antarctica may not have been manganese‐limited. Although light and iron treatments did not impact species composition, high methionine synthase indicated that diatoms could have experienced stress induced by low vitamin B12, potentially contributing to P. antarctica's general dominance throughout the experiments. Our results indicate that P. antarctica may be better adapted to spring conditions than diatoms.

Nutrient regulation of biological nitrogen fixation across the tropical western North Pacific.

Nitrogen fixation is critical for the biological productivity of the ocean, but clear mechanistic controls on this process remain elusive. Here, we investigate the abundance, activity, and drivers of nitrogen-fixing diazotrophs across the tropical western North Pacific. We find a basin-scale coherence of diazotroph abundances and N2 fixation rates with the supply ratio of iron:nitrogen to the upper ocean. Across a threshold of increasing supply ratios, the abundance of nifH genes and N2 fixation rates increased, phosphate concentrations decreased, and bioassay experiments demonstrated evidence for N2 fixation switching from iron to phosphate limitation. In the northern South China Sea, supply ratios were hypothesized to fall around this critical threshold and bioassay experiments suggested colimitation by both iron and phosphate. Our results provide evidence for iron:nitrogen supply ratios being the most important factor in regulating the distribution of N2 fixation across the tropical ocean.

Controls on turnover of marine dissolved organic matter—testing the null hypothesis of purely concentration‐driven uptake: Comment on Shen and Benner, “Molecular properties are a primary control on the microbial utilization of dissolved organic matter in the ocean”

Controls on turnover of marine dissolved organic matter—testing the null hypothesis of purely concentration‐driven uptake: Comment on Shen and Benner, “Molecular properties are a primary control on the microbial utilization of dissolved organic matter in the ocean”

Reply to comment: Controls on turnover of marine dissolved organic matter—testing the null hypothesis of purely concentration‐driven uptake

AbstractOur recent bioassay experiments indicate that molecular properties are a primary control on the microbial utilization of dissolved organic matter in the ocean. This finding is questioned by Lennartz and Dittmar who modeled our experiments and concluded that our observations could be largely explained by concentration‐driven uptake independent from molecular properties. We suggest the authors' models are deficient for establishing the relative roles of molecular properties and concentration‐driven uptake. Our conclusion is consistent with earlier and recent experimental results and biogeochemical observations, supporting a unified theory with molecular properties as a more prominent control than concentration‐driven uptake on marine organic carbon accumulation.

Microcosm investigation on the allelochemic potential of Ageratum conyzoides on selected food crop

Invasive alien plants like Ageratum conyzoides influence the growth, yield, development, and productivity of food crops. The various allelochemicals present in A. conyzoides exert stimulatory or inhibitory effects on the food crops. In this microcosm investigation through pot experiments, we evaluated the allelopathic potential of A. conyzoides on the germination and seedling growth of a leafy vegetable of nutritional value i.e., Lactuca sativa. The soil samples were collected from two different sites i.e., healthy forest soil and soil invaded by A. conyzoides. The healthy forest soil was considered as control pot while A. conyzoides invaded soil was selected for the experimental pot. The inhibitory effect of the invasive plant was observed on the tested crop of dietary value in human nutrition. The results revealed that the germination of the seeds is inhibited and suppressed by A. conyzoides. Microcosm studies demonstrated that out of the 15 seeds planted on both pots, 13 seeds germinated and thrived on the experimental pot and 14 on the control pot. The seedling height (32.1 cm), shoot length (27.65 cm), seedling biomass (1.866 g) and vigor index (6.829) were recorded higher in the experimental pot. Whereas, the root length (4.8 cm), germination potential (0.93), germination percentage (93.33%), germination index (4.66) and germination rate index (434.91) were noted higher in the control pot. A. conyzoides therefore showed both the inhibitory and stimulatory effects on L. sativa and thereby exhibited both positive and negative allelopathic effects. Further, bioassay experiments with other bioassay crops can elucidate the chemical ecology and allelopathy potential of A. conyzoides

EFFECT OF DIFFERENT BIOCHAR CONCENTRATION ON THE GROWTH OF THREE AGRICULTURAL PLANTS IN AFGHANISTAN

The present research was conducted in the laboratory of Badakhshan University, Afghanistan. The study was carried out for 40 days in 2021, to document the effect of biochar on the growth of three important agricultural plant species: radish, lettuce and spinach. The biochar was produced from the biomass of Oak tree under oxygen less condition. The study includes assessment of Petri plate bioassay and pot scale experiment to understand the effect of biochar under saline and non-saline conditions in order to mitigate the problem of salinity. Application of biochar has significantly increased the seed germination for all the seeds. The maximum seed germination was observed for radish > lettuce > spinach. NaCl has reduced the percentage of seed germination but a little increase was observed in case of radish as compared to lettuce and spinach. However, application of biochar has significantly increased its growth as compared to control plant. Both shoot and root of all three studied plants were increased with increase in BC concentrations. The maximum length of root was observed for radish > lettuce > spinach whereas for shoot it was lettuce > radish > spinach. At the same time application of 5 % biochar helped to improve the growth of both radish shoot and root. Lettuce was found sensitive to saline condition and application of biochar does not significantly improve their morphometric parameters. Spinach could be considered as moderately saline resistant species whose biomass can be improved by supplementing with biochar.

Mosquito larvicidal and antimicrobial activities of synthesized silver nanoparticles (AgNP) using mature fruit extract of Cestrum diurnum L.

Silver nanoparticles (AgNP) were prepared using mature fruit extract of Cestrum diurnum L. (family: Solanaceae) as a reducing agent. The stabilized AgNPs were characterized by time-dependent UV–Vis Spectrophotometric analysis. The spherical/oval shape of the nanoparticle was confirmed by Transmission Electron Microscopy analysis with an average particle size of about 50 nm. The crystalline nature of the AgNPs was confirmed in the XRD spectrum by the characteristic Bragg peaks. Fourier Transform Infrared Spectroscopic analysis of AgNPs confirms the presence of several functional groups. AgNPs showed effective larvicidal activities against larval instars of Anopheles stephensi and Culex quinquefasciatus mosquitoes in the laboratory bioassay. Synthesized AgNPs also showed good antibacterial activity against some fish pathogenic and human pathogenic bacteria which is evident from the inhibition zone diameter in the antibacterial bioassay experiment.

Plant Growth Promoting Microorganism Selection and Activity Test for Reforestation of Topsoil Restoration Site

Objectives : This study was conducted to investigate the applicability of plant growth promoting microorganisms during restoration through re-vegetation of damaged topsoil.Methods : As the vegetation to be applied to the restoration site, Weigela subsessilis, Spiraea prunifolia, Pine densiflora, Pennisetum alopecuroides were selected. An attempt was made to isolate plant growth promoting microorganisms from the root zone of plants of the same species inhabiting domestic park sites and hiking trails. Plant growth promoting activities such as phosphate solubilization ability, siderophore production ability, IAA production ability, and ACC deaminase production ability were examined, and the species to be finally applied was selected and then identified. Among the strains whose plant growth promoting activity was confirmed, Arthrobacter sp. 1B2 and Paraburkholderia terrae 1P2 were applied to the genitalia and pine, respectively, and a pot experiment was conducted to confirm the activity.Results and Discussion : Forty-five strains were isolated from Weigela subsessilis, Spiraea prunifolia, Pine densiflora, Pennisetum alopecuroides and the IAA-producing ability and ACC deaminase-producing ability were confirmed for 16 strains whose phosphate solubilizing ability and siderophore-producing ability were confirmed. After selecting and identifying strains with excellent plant growth promoting ability, strains such as Cupriavidus sp, Arthrobacter sp., Pseudomonas fluorescens, Pseudomonas sp., Paraburkholderia terrae were obtained. Among them, Arthrobacter sp. 1B2 and Paraburkholderia terrae 1P2 strains were applied to genitalia and pine, respectively, and it was confirmed that plant growth was promoted.Conclusions : Bioassay experiments and field applications using plant growth promoting microorganisms have been mainly studied for herbaceous species (Grandaceae, corn, oats, etc.). However, in this study, the applied plants are shrubs class, which do not significantly grow in length, targeting damaged areas with high subsoil content, which are poor in environment and insufficient in organic and inorganic matter. Therefore, it is meaningful in that the activity of plant growth promoting microorganisms focused on absorption of inorganic substances, such as phosphate solubilization activity and siderophore ability, was investigated and the activity was confirmed by performing a bioassay.

Predictive modeling and therapeutic repurposing of natural compounds against the receptor-binding domain of SARS-CoV-2

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a member of the Coronaviridae family, causing major destructions to human life directly and indirectly to the economic crisis around the world. Although there is significant reporting on the whole genome sequences and updated data for the different receptors are widely analyzed and screened to find a proper medication. Only a few bioassay experiments were completed against SARS-CoV-2 spike protein. We collected the compounds dataset from the PubChem Bioassay database having 1786 compounds and split it into the ratio of 80–20% for model training and testing purposes, respectively. Initially, we have created 11 models and validated them using a fivefold validation strategy. The hybrid consensus model shows a predictive accuracy of 95.5% for training and 94% for the test dataset. The model was applied to screen a virtual chemical library of Natural products of 2598 compounds. Our consensus model has successfully identified 75 compounds with an accuracy range of 70–100% as active compounds against SARS-CoV-2 RBD protein. The output of ML data (75 compounds) was taken for the molecular docking and dynamics simulation studies. In the complete analysis, the Epirubicin and Daunorubicin have shown the docking score of −9.937 and −9.812, respectively, and performed well in the molecular dynamics simulation studies. Also, Pirarubicin, an analogue of anthracycline, has widely been used due to its lower cardiotoxicity. It shows the docking score of −9.658, which also performed well during the complete analysis. Hence, after the following comprehensive pipeline-based study, these drugs can be further tested in vivo for further human utilization. Communicated by Ramaswamy H. Sarma

Stockpiling disrupts the biological integrity of topsoil for ecological restoration

PurposeBiotic and abiotic properties of soils can hinder or facilitate ecological restoration, and management practices that impact edaphic factors can strongly influence plant growth and restoration outcomes. Salvaged topsoil is an invaluable resource for mine-site restoration, and a common practice is topsoil transfer from mined areas to restoration sites. However, direct transfer is often not feasible, necessitating storage in stockpiles. We evaluated the effects of topsoil stockpiling on plant performance across diverse ecosystems impacted by mining throughout Western Australia.MethodsWe conducted a bioassay experiment using a widespread native Acacia species to assess how topsoil storage might impact plant growth, physiology, and nodulation by N-fixing bacteria using soils from native reference vegetation and stockpiled soils from six mine sites across Western Australia.ResultsPlant responses varied across mine sites, but overall plants performed better in soils collected from native vegetation, exhibiting greater biomass, more root nodules, and higher water-use efficiency compared to those grown in stockpiled soils. Soil physiochemistry showed few and minor differences between native soils and stockpiles.ConclusionResults strongly suggest observed differences in plant performance were biotic in nature. This study highlights the negative effects of topsoil storage on the biological integrity of soil across diverse ecosystems, with important implications for mine-site restoration; our results show that topsoil management can strongly influence plant performance, and stockpiled soils are likely inferior to recently disturbed topsoil for restoration purposes. We also use this study to illustrate the utility of bioassays for assessing soil quality for ecological restoration.

Biological effect of two plant extracts against house flies (Musca domestica L.) as a sustainable approach for vector disease control

AbstractThe house fly, Musca domestica (L.) has a worldwide distribution and acts as a source of nuisance and a common vector for several diseases in humans and livestock. The present study aimed to investigate the biological activity of plant extracts (Juniperus procera and Ficus palmata) along with their synthesized silver nanoparticle (AgNP) solutions against the second larval stage of house flies. Larval bioassay experiments were conducted using feeding and dipping methods at various concentrations. The synthesized silver nanoparticles were characterized by visual observation, UV–visible and FTIR spectroscopy. The results showed biochemical effects of the tested extracts on the treated larvae and different growth stages of the house fly. Using the feeding and dipping methods, the concentration required to inhibit 50% of the adult fly emergence (IC50 value) was 2.62% and 4.19% with J. procera and 0.71% and 1.29% with F. palmata, respectively. The crude extracts mixed with silver nanoparticles showed significantly decreased IC50 values at 1.09% and 1.23% for J. procera and 0.32% and 0.45% for F. palmata using the feeding and dipping methods, respectively. Further, the feeding method with both crude extracts showed about 1.60 and 1.80 times more effective control against the larval stages compared to that in case of the dipping method. In addition, the F. palmata extract was about 3.66 and 3.20‐fold more effective against flies compared to J. procera using the feeding and dipping method, respectively. Overall, this study suggests using of the tested extracts of plants as promising biological agents and safe options for sustainable pest management.

Biological activity of Arum Cyreniacum (Araceae) and potential use as Bioherbicide

The present investigation aims was carried out to study the biological activity of aqueous extract and shoot crude powder of Arum cyreniacum (ACSAE and ACSCP) on some germination and growth parameters (germination bioassay experiment) besides major physiological, and biochemical processes (pot experiment) In Hordeum vulgare (crop species) and Phalaris minor (weed species) of different concentrations of A. cyreniacum on germination percentage (GP), coleoptile (CL) and radicle (RL) lengths, seedling shoot and root length seedling fresh and dry weight, some nutrients (N, K, Na, Cu, Fe, and Ni ), and photosynthetic pigments .Generally, the effect of the all concentrations levels of the extract on (GP), (CL) and (RL) on H. vulgare seeds was ineffectively decreased with increasing the concentrations of A. cyreniacum while the percentage was significantly decreased with increasing the concentrations of the with P. minor. All concentrations levels of the extracts reduced coleoptile (CL) and radicle (RL) lengths of H. vulgare. Likewise, the reduction in the two parameters was documented in P. minor. Were more affected in P. minor compared to H. vulgare. There was a significant within the concentration of micronutrients as well as the entire photosynthetic color substance of P. minor seedlings grown in ACSCP. Treatment with ACSCP had a more negative effect on total nitrogen in P. minor than on H. vulgare. Keywords: R Hordeum Vulgare; Growth Parameters; Nutrient Content; Photosynthetic Pigments

Heterospecific Neighbor Plants Impact Root Microbiome Diversity and Molecular Function of Root Fungi.

Within the forest community, competition and facilitation between adjacent-growing conspecific and heterospecific plants are mediated by interactions involving common mycorrhizal networks. The ability of plants to alter their neighbor’s microbiome is well documented, but the molecular biology of plant-fungal interactions during competition and facilitation has not been previously examined. We used a common soil-plant bioassay experiment to study molecular plant-microbial interactions among rhizosphere communities associated with Pinus taeda (native host) and Populus trichocarpa (non-native host). Gene expression of interacting fungal and bacterial rhizosphere communities was compared among three plant-pairs: Populus growing with Populus, Populus with Pinus, and Pinus with Pinus. Our results demonstrate that heterospecific plant partners affect the assembly of root microbiomes, including the changes in the structure of host specific community. Comparative metatranscriptomics reveals that several species of ectomycorrhizal fungi (EMF) and saprotrophic fungi exhibit different patterns of functional and regulatory gene expression with these two plant hosts. Heterospecific plants affect the transcriptional expression pattern of EMF host-specialists (e.g., Pinus-associated Suillus spp.) on both plant species, mainly including the genes involved in the transportation of amino acids, carbohydrates, and inorganic ions. Alteration of root microbiome by neighboring plants may help regulate basic plant physiological processes via modulation of molecular functions in the root microbiome.

Enhanced Biodegradation of Dissolved Organic Carbon in the Western Boundary Kuroshio Current When Intruded to the Marginal South China Sea

AbstractThe advective supply of allochthonous dissolved organic carbon (DOC) from open ocean to marginal seas through western boundary current intrusion influences the regional carbon inventory and microbial activities. However, there is limited observation about this process and its biogeochemical impacts on marginal seas. In this study, we investigated the biodegradation of allochthonous DOC carried by the intrusion of the Kuroshio Current into South China Sea (SCS). Using an isopycnal mixing model, the exchange and biodegradation processes of Kuroshio‐intruded DOC were quantified. We estimated that approximately 10% of the surface DOC was remineralized due to the enhanced biodegradation in the SCS. This result was supported by the on‐deck bioassay experiments that were conducted under different environmental contexts. The results of modeling and on‐deck incubations indicate that DOC biodegradation was enhanced by the sharp gradient of environment factors, including nutrients supply, microbial species, and bio‐lability of DOC in the frontal zone during the surface water mass mixing. The amount of carbon released from the enhanced DOC degradation by Kuroshio intrusion was estimated to be approximately equal to 8.6 Tg C yr−1. Concomitantly, the amount of nitrogen released could contribute 0.19–0.70 mmol N m−2 d−1 to the surface of SCS which is comparable to the total supply from deeper water and nitrogen fixation in surface waters. This study suggests that the enhanced biodegradation of DOC during the western boundary currents intrusion could serve as an important sink of oceanic DOC, and thus provide an additional nutrient source to marginal seas.

Reduction in mercury bioavailability to Asian clams (Corbicula fluminea) and changes in bacterial communities in sediments with activated carbon amendment

Activated carbon (AC) amendment is considered as one of the alternatives for managing and remediating mercury (Hg) contaminated sediments because of its high sorptive capacity and potential to immobilize the contaminant. For this study, the underlying mechanisms that control the reduction of Hg bioavailability in AC-amended estuarine sediments were investigated in box microcosm set-ups with 28-day Asian clam bioassay experiments. The application of diffusive gradients in thin film technique (DGT) revealed that the total mercury and methylmercury levels in sediment pore water decreased by 60%–75% in 1%–3% AC-amended sediments. This decrease subsequently led to a linear reduction in the Hg body burden in Asian clams, even at 1% sorbent mixing. These observations implied that AC amendment reduced the net flux of Hg into the pore water and overlying water, resulting in reduced Hg bioaccumulation in benthic organisms. The addition of AC to sediment also led to reduced dissolved organic carbon and several biogeochemical indicators (HS−, Mn, and Fe) in the pore water. Furthermore, the 16 S rRNA gene amplicon sequencing analysis revealed noticeable alterations in the microbial communities after AC amendment. The predominant phylum was Firmicutes in control sediment, Bacteroidetes in 1% AC-amended sediment, and Proteobacteria in both 2% and 3% AC-amended sediment samples. The genera-level analysis showed that the relative abundance of the Hg-methylators decreased as the level of AC amendment increased. These observations suggested that AC amendment decreased Hg bioavailability not only by physicochemical sorption but also by changing geochemical species and shifting the microbial community composition.

Acacia auriculiformis pericarp – a substitute of Mohua oil cake as piscicide in pre-stocking pond preparation

Mahua oil cake (MOC), a derivative of the seeds from Bassia latifolia is used as a piscicide in pre-stocking pond preparation for composite fish culture. However, for its nutritional potency MOC is used as a protein substitute in the formulated diets for fish, poultry and cattle. In present experiment piscicidal potency of Acacia pericarp preparation (APP) has been evaluated to get a substitute of MOC. LC-ESI-MS analysis of the methanolic extract of Acacia auriculiformis pericarp revealed seven triterpenoid saponins (acaciasides), twenty two flavonoids, eight tannins and a phenolic rich fraction- gallyl glucose. In the present experiment Minimum lethal concentration, LC50 and LC100 of APP were worked out through static bioassay and subsequent probit analyses putting trial upon nine potential predator fishes viz. Channa punctatus (Bloch), Channa gachua (Hamilton), Channa striata (Bloch), Clarias batrachus (Lin), Clarias gariepinus (Burchell), Heteropneustes fossilis (Bloch), Anabas testudineus (Bloch), Notopterus notopterus (Pallas) and Wallago attu (Bloch & Schneider). Among the native species C. striata exhibited its toxicological response with higher Minimum lethal concentration (70 ppm), LC50 (78.7 ppm) and LC100 (90 ppm). Toxicological response of the exotic species C. gariepinus however, were found to be with highest LC50 (98.4 ppm) and LC100 (130 ppm). On the basis of toxicological response of different predator species the piscicidal application concentration of APP has been recommended in reference to LC100 of C. striatus. However, if the exotic species C. gariepinus is present in the system, APP application should be made with reference to LC100 to this species. Kaplan-Meier analysis on survivality of fish under exposure was performed to justify the results of the bioassay experiments. APP has the least effect on non-target invertebrate organisms of the aquatic body. Application of APP results in improving soil nutrients such as NPK and organic carbon. The result of the study revealed that Acacia pericarp could be a better substitute of MOC as a piscicide.

Palmer Amaranth (Amaranthaceae) and At-Plant Insecticide Impacts on Tarnished Plant Bug (Hemiptera: Miridae) and Injury to Seedling Cotton Terminals

Abstract The direct effect of Palmer amaranth, Amaranthus palmeri Watson, on cotton growth and development is well documented, but its indirect effect through harboring feeding insects is less understood. Palmer amaranth emerged with cotton and remaining in the field for 30 days increased tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), populations compared with a weed-free system. Weedy systems noted up to 49% more damaged terminals than weed-free systems, with cotton yield decreasing as damaged terminals increased at one of two locations. Thrips (Thysanoptera: Thripidae) populations were effectively controlled with Aeris® (Bayer, St. Louis, MO) seed treatment (imidacloprid + thiodicarb at 0.375 mg active ingredient per seed), but there was no correlation between thrips infestations and increasing damaged cotton terminals. However, Aeris seed treatment significantly reduced the occurrence of damaged cotton terminals. In a second experiment, Palmer amaranth infesting an area adjacent to a weed-free cotton field had maximum damaged terminals of 51% on the cotton row proximal to the weedy area, with the distal cotton row (44 m away) having 8% terminal damage. Cotton yield significantly decreased as damaged terminals increased. A final bioassay experiment further evaluated the influence of seed treatment on tarnished plant bug feeding impacting cotton seedlings. With Aeris seed treatment, tarnished plant bug mortality was 97%, compared with 37% for nontreated seed. Results suggest tarnished plant bug infestations increased where Palmer amaranth was present in cotton fields. Additionally, greater Palmer amaranth infestations led to an increase in damaged cotton terminals and lower yields.

Mortality and physiological impacts of the tea saponin against Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

The toxicity of a tea saponin (TS) was investigated on mortality, digestive system, detoxifying and antioxidant enzymes of Ephestia kuehniella Zeller. The larvae were fed on a diet containing different concentrations of TS (5, 10, 20, 40, and 80 mg/mL) to determine the lethal dose and the lethal exposure time. The LC50 of TS was calculated as 28 mg/mL while the LT5 value was found to be 4.14 days following the bioassay experiment. The activities of all enzymes except for lipase decreased in the TS-fed larvae, while the activities of general esterase and glutathione S-transferases as the detoxification enzymes significantly increased contradictory. Moreover, the larvae fed on TS demonstrated the higher activities of antioxidant enzymes including superoxide dismutase, peroxidase, and catalase in addition to the content of malondialdehyde. These findings indicated the significant toxic effects of TS on inhibition of digestive activities and induction of antioxidant enzymes which developed our knowledge on physiological disruptions due to TS treatment.

English

The current research work was conducted for the evaluation of repellent and growth inhibitory potential of Azadirachta indica, Murraya koenigii, Nicotiana tobacum and Liquorice against Callosobruchus chinensis (L.). Each plant extract was tested with four concentrations viz; 5, 10, 15 & 20 % for bioassay experiments. Repellent potentials of acetone extract of the plants were evaluated by using the area preference method against the pulse beetle. The four dilutions of the extracted plant materials (extract) were used at one half of the filter papers (of each) while remaining halves were solely treated with acetone (used as control experimental unit) for the comparison purposes. Data regarding repellence were taken after 12, 24 and 48 hours of the post treatment. In repellency bioassay, the highest (93.32%) repellence of Callosobruchus chinensis was observed for which against 20% concentration of A. indica extract, whereas lowest repellence (78.87%) was recorded in case of Liquorice. Repellency values of 90.07% and 84.76% were recorded in extracts of M. koenigii and N. tobacum in Faisalabad strain. In case of Lahore strain highest repellence of C. chinensis was observed for which 95.16% at 20% concentration of A. indica extract was whereas relatively lowest value (82.04%) was recorded in case of Liquorice. Repellency values of 87.27% and 91.06% were recorded in extracts of M. koenigii and N. tobacum. The results regarding growth inhibitory effect revealed that highest mean progeny inhibition (78.12%) was noted at 20% dose rate of A. indica extracted plant material after longest exposure time (60 days). Comparatively lowest inhibition (28.21%) was noted after 30 days exposure period at 5% dilution of Liquorice extract in Faisalabad strain. Mean inhibition of progeny was found directly dependent on both time as well as concentration, applied. Results revealed that highest mean progeny inhibition (85.03%) was recorded at 20% concentration of A. indica extract after longest exposure time (60 days). Comparatively, lowest inhibition (35.18%) was recorded at 5% after 30 days of application of Nicotiana tobacum extract in Lahore strain. Hence, use of plant-based materials can be helpful for the ecofriendly management of the stored grains insect pests as a part of IPM program.