Tetranychus Urticae Research Articles

Grafting increases superoxide dismutase and catalase activity to overcome the impact of the two-spotted spider mite on eggplant growth and productivity

Grafting vegetable crops is considered a valuable tool for improving the yield and quality of fruits under various stress conditions. This study aimed to assess the influence of grafting eggplant Solanum melongena (cv. A338) onto Solanum torvum rootstock (cv. STT3) on the incidence of the two-spotted spider mite Tetranychus urticae (TSSM). An experimental study was conducted to investigate the defense response elicited, as assessed by measuring the activities of antioxidant enzymes like superoxide dismutase (SOD) and catalase (CAT), as well as hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and chlorophyll contents in grafted and non-grafted eggplants under different TSSM infestation levels (10, 30 and 50 adults per plant). In addition, the effect of grafting on plant growth and yield of eggplant was evaluated. According to the findings of the present study, grafted plants had a lower density of TSSM than non-grafted plants. The number of eggs, nymphs, and adults on grafted plants was 40.11%, 31.71%, and 27.54%, respectively, lower than on non-grafted plants. With increasing TSSM density, the activities of CAT and SOD were increased at varying degrees. In terms of SOD activity, the grafted plants outperformed both the non-grafted scion and rootstock at all TSSM densities. In addition, the results demonstrated that plants with greater CAT activity were able to maintain a lower H<sub>2</sub>O<sub>2</sub> content and vice versa. The lower negative impacts on photosynthetic pigments demonstrated that grafted plants on S. torvum were more resistant to mite-induced damage to chlorophyll and carotenoids as mite density elevated. The grafted plants were superior in vegetative growth, and the total fruit weight was found to be two times higher than non-grafted plants. The features modified by grafting, such as the increased activities of SOD and CAT, can alleviate the impact of TSSM. Therefore, grafting could constitute a valuable tool when combined with other strategies of Integrated Pest Management (IPM) in the two-spotted spider mite control programs.

Increasing Cyetpyrafen Spray Volume and Ozone Spray Improves the Control Effects against Two-Spotted Spider Mite (Tetranychus urticae) in Strawberries.

The two-spotted spider mite (Tetranychus urticae) is a constant threat to greenhouse strawberry production. The application of synthetic acaricides is the main method of controlling T. urticae. However, resistance development to traditional acaricides reduces their efficacy and eventually leads to control failure. It is important for strawberry growers to look for new acaricides and application technologies that can limit the harmfulness of T. urticae in environmentally friendly ways. In the current study, laboratory toxicity tests and field trials were performed to screen high-efficiency acaricides, and then application technologies were improved to enhance the management of T. urticae. In the laboratory toxicity tests, the results showed that the LC50 (median lethal concentration) value of cyetpyrafen, cyenopyrafen, cyflumetofen, bifenazate, abamectin, azocyclotin, pyridaben, spirodiclofen, and etoxazole against adult T. urticae was 0.226, 0.240, 0.415, 3.583, 5.531, 25.58, 39.69, 140.3, and 267.7 mg/L, respectively. In addition, the LC50 value of the nine acaricides against eggs of T. urticae was 0.082, 0.097, 0.931, 18.56, 25.52, 45.61, 36.32, 1.954, and 0.040 mg/L, respectively. The field trial results showed that the best control effect was obtained in cyetpyrafen at 300 mL/ha treatment. Cyetpyrafen was chosen for further application technology tests. In the spray volume tests, the results showed that increasing the spray volume from 900 to 1050 L/ha significantly improved the control of T. urticae. In addition, the results from the spray instrument tests demonstrated that the control effects on T. urticae in the ozone spray treatments were significantly higher than those of the conventional and electrostatic sprays 1 and 3 days after treatment (DAT). Therefore, this study suggested that cyetpyrafen effectively controlled T. urticae both in the laboratory tests and in the field trials. Increasing the spray volume and application of ozone spray significantly improved T. urticae management.

Sublethal effects of a spiromesifen and abamectin combination on Tetranychus urticae (Acari: Tetranychidae) and its predators Phytoseiulus persimilis and Amblyseius swirskii (Acari: Phytoseiiidae).

The two-spotted spider mite, Tetranychus urticae Koch (TSSM), is an important cosmopolitan pest of agricultural crops that is often managed in greenhouses by augmentation of predatory mites in combination with acaricides. Here we examined the transgenerational effects of low lethal concentrations of a widely-used acaricide, Oberon Speed® (a combination of spiromesifen and abamectin), on the life history traits and population growth of T. urticae and two of its predators, Phytoseiulus persimilis Athias-Henriot and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae). The concentrations employed corresponded to the LC10, LC20 and LC30 values estimated for TSSM protonymphs 48h post-exposure in a topical bioassay, which yielded an LC50 value of 207.2ppm. Parental exposure of TSSM to all three low concentrations increased the total developmental time of progeny; both the LC20 and LC30 treatments reduced adult longevity and number of oviposition days, but only the LC30 treatment increased the preoviposition period. Similarly, both the LC20 and LC30 treatments significantly reduced life table parameters (r, R0, λ, and GRR), and increased generation time (T) and population doubling time (DT). Although maternal exposure to the acaricide had various impacts on progeny life history, A. swirskii was less affected than P. persimilis, suggesting the former species would be more compatible for integration with Oberon Speed® for control of T. urticae in greenhouse vegetable production.

Current and future invasion risk of tomato red spider mite under climate change.

Tomato red spider mite Tetranychus evansi Baker and Pritchard (Acari: Tetranychidae) is a phytophagous pest that causes severe damage to Solanaceous plants worldwide, resulting in significant economic losses. In this study, the maximum entropy model was used to predict the potential current (1970-2000) and future (2021-2060) global distribution of the species based on its past occurrence records and high-resolution environmental data. The results showed that the mean values of the area under the curve were all >0.96, indicating that the model performed well. The three bioclimatic variables with the highest contributions were the coldest quarterly mean temperature (bio11), coldest monthly minimum temperature (bio6), and annual precipitation (bio12). A wide range of suitable areas was found across continents except Antarctica, both currently and in the future, with a much larger distribution area in South America, Africa, and Oceania (Australia), dominated by moderately and low suitable areas. A comparison of current and future suitable areas reveals a general trend of north expansion and increasing expansion over time. This study provides information for the prevention and management of this pest mite in the future.

Coinfection accelerates transmission to new hosts despite no effects on virulence and parasite growth.

One of the fundamental aims of ecological, epidemiological and evolutionary studies of host-parasite interactions is to unravel which factors affect parasite virulence. Theory predicts that virulence and transmission are correlated by a trade-off, as too much virulence is expected to hamper transmission owing to excessive host damage. Coinfections may affect each of these traits and/or their correlation. Here, we used inbred lines of the spider mite Tetranychus urticae to test how coinfection with T. evansi impacted virulence-transmission relationships at different conspecific densities. The presence of T. evansi on a shared host did not change the relationship between virulence (leaf damage) and the number of transmitting stages (i.e. adult daughters). The relationship between these traits was hump-shaped across densities, both in single and coinfections, which corresponds to a trade-off. Moreover, transmission to adjacent hosts increased in coinfection, but only at low T. urticae densities. Finally, we tested whether virulence and the number of daughters were correlated with measures of transmission to adjacent hosts, in single and coinfections at different conspecific densities. Traits were mostly independent, meaning that interspecific competitors may increase transmission without affecting virulence. Thus, coinfections may impact epidemiology and parasite trait evolution, but not necessarily the virulence-transmission trade-off.This article is part of the theme issue 'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics'.

The Main Pests Are Insects and Diseases of Agricultural Crops in the South of Kyrgyzstan

In the south of Kyrgyzstan, the largest areas are occupied by agrocenosis of vegetable, fruit, industrial, and grain crops. The article presents the main pests and pathogens of agricultural crops in the south of Kyrgyzstan. The purpose of the research is to identify the dominant pests and diseases of agricultural crops and to find effective biological measures to combat them in the conditions of southern Kyrgyzstan. In recent years, outbreaks of mass reproduction of tomato mining moth (Tuta absoluta (Meyrick, 1917)) on tomatoes, cherry slimy sawfly (Caliroa cerasi (Linnaeus, 1758)) and cherry fly (Rhagoletis cerasi (Linnaeus, 1758)) on cherries and cherries, Colorado potato beetle (Leptinotarsa decemlineataSay), late blight (Phytophthora infestans (Mont.) de Bary) on potatoes, powdery mildew (Erysiphe cichoracearum f. cucurbitacearumPot.) on vegetables, corn moth (Ostrinia nubilalis Hübner, 1796), bread beetle (Zabrus tenebrioides (Goeze, 1777)) and bug (Eurygaster integriceps Puton, 1881) on cereals, mite (Tetranychus urticae), aphid (Aphidoidea) and cotton scooper (Helicoverpa armigera Hübner) on cotton, phytonomus (Phytonomus variabilis) on perennial grasses, winter scooper (Agrotis segetum (Denis et Schiffermüller) 1775), apple moth (Carpocapsa pomonella (Linnaeus, 1758)), apple moth (Hyponomeuta malinellus (Zeller, 1838)), unpaired silkworm (Lymantria dispar Linnaeus, 1758), curly leaves (Taphrina deformans (Berk.) Tul.), bacterial burn (Erwinia amylovora (Burrill, 1882) Winslow et al., 1920), scab (Venturia inaequalis (Cooke) G. Winter) and powdery mildew on fruit crops, epiphytotic rust diseases (Puccinia) of cereals, oatmeal (Avena fatua) and sunflowers (Barbarea vulgaris) on cereals. An overview of drugs used in crop protection systems is also given. Chemical pesticides still remain the main means of protecting agricultural crops from pests and diseases, in the future, the use of the latest technologies in plant protection, the introduction of new biological preparations into plant protection practice should be used.

Effect of Eucalyptus globulus and Ferula assafoetida essential oils and their nanoformulations on the life table parameters of Tetranychus urticae (Acari: Tetranychidae).

One of the most damaging pests of agricultural crops across the globe is the two-spotted spider mite, Tetranychus urticae Koch. A wide variety of arthropods and plant pathogens can be controlled by essential oils, which are secondary metabolites produced by plants. It is possible to enhance the stability as well as the anti-pest efficiency of plant essential oils by encapsulation. Water distillation was used to extract the essential oils from Eucalyptus globulus and Ferula assafoetida. The chitosan nanoparticles were used to load both essential oils into nanoformulations. Studies were conducted on T. urticae life table characteristics under experimental circumstances to determine the sublethal impacts of essential oils and their nanoformulations. Intrinsic growth rate (r) for population exposed to E. globulus, F. assafoetida essential oils, their nanoformulations and the control were 0.1, 0.069, 0.051, 0.018 and 0.21 per day, respectively. F. assafoetida and E. globulus nanoformulations resulted the lowest fecundity compared to the other treatments. According the result of the lethal and sublethal effects of purified essential oils and nanoformulations of F. assafoetida and E. globulus, they would be recommended for controlling the two-spotted spider mites, T. urticae.

Using predatory species and entomopathogenic fungi as alternatives to chemical pesticides in green bean field

BackgroundGreen bean, Phaseolus vulgaris L. (Fam.: Leguminosae) is a widely consumed grain legume prized for its edible seeds and pods. It is susceptible to infestations with various pests as insects and mites throughout the growing season. In this study, the efficacy of the predatory species, Chrysoperla carnea (Stephens), Phytoseiulus persimilis Athias-Henriot and the entomopathogenic fungus (EPF) Metarhizium anisopliae (Hypocreales: Clavicipitaceae), as well as conventional pesticides, Mospilan and Vertimec, were evaluated against the most important pests, mainly the whitefly, Bemisia tabaci (Genn.) and the two-spotted spider mite, Tetranychus urticae Koch, infesting the green beans cultivated at two locations Giza and El-Menoufia Governorates in Egypt.ResultsThe findings demonstrate that treatments using C. carnea and M. anisopliae effectively reduced the whitefly population, while pesticide treatments were comparatively less effective. In the Giza plots, at the end of the experiments, the use of both M. anisopliae and C. carnea showed high reductions in whitefly population (85.57 and 84.87%), respectively, while in El-Menoufia, C. carnea (97.74%) was the most effective treatment followed by M. anisopliae (90.32%). Pesticide treatment in this case yielded a reduction rate of (22.76 and 59.67%) in Giza and El-Menoufia plots, respectively. However, for spider mite control, P. persimilis proved to be the most effective treatment in Giza and El-Menoufia plots, reducing the spider mite population to 98.44 and 96.14%, respectively. Metarhizium anisopliae treatment also displayed moderate effectiveness, with reduction rates of 75.62 and 75.37% in Giza and El-Menoufia plots, respectively. In comparison, pesticide treatment showed low effectiveness, with reduction rates of only 23.92 and 53.16% in the two locations, respectively.ConclusionApplications of the predator, C. carnea and the EPF, M. anisopliae were highly effective in reducing the population of whitefly, while the predator mite P. persimilis proved to be the most effective for controlling the spider mites. Overall, the study suggests that biocontrol agents, such as the predators and the EPF, can be considered as alternatives to synthetic chemical pesticides for controlling pests infesting green beans.

QTL analysis on a lemon population provides novel insights on the genetic regulation of the tolerance to the two-spotted spider mite attack

BackgroundAmong the Citrus species, lemon (Citrus limon Burm f.) is one of the most affected by the two-spotted spider mite (Tetranychus urticae Koch). Moreover, chemical control is hampered by the mite’s ability to develop genetic resistance against acaricides. In this context, the identification of the genetic basis of the host resistance could represent a sustainable strategy for spider mite control. In the present study, a marker-trait association analysis was performed on a lemon population employing an association mapping approach. An inter-specific full-sib population composed of 109 accessions was phenotyped through a detached-leaf assays performed in modified Huffaker cells. Those individuals, complemented with two inter-specific segregating populations, were genotyped using a target-sequencing approach called SPET (Single Primer Enrichment Technology), the resulting SNPs were employed for the generation of an integrated genetic map.ResultsThe percentage of damaged area in the full-sib population showed a quantitative distribution with values ranging from 0.36 to 9.67%. A total of 47,298 SNPs were selected for an association mapping study and a significant marker linked with resistance to spider mite was detected on linkage group 5. In silico gene annotation of the QTL interval enabled the detection of 13 genes involved in immune response to biotic and abiotic stress. Gene expression analysis showed an over expression of the gene encoding for the ethylene-responsive transcription factor ERF098-like, already characterized in Arabidopsis and in rice for its involvement in defense response.ConclusionThe identification of a molecular marker linked to the resistance to spider mite attack can pave the way for the development of marker-assisted breeding plan for the development of novel selection coupling favorable agronomical traits (e.g. fruit quality, yield) with a higher resistance toward the mite.

To move or not to move: Dispersal of Orius insidiosus in strawberry plants

AbstractSpatial and temporal distribution of food resources influences predatory insects' foraging and dispersal behavior. Orius insidiosus (Say) (Hemiptera: Anthocoridae) is a good biological control agent of western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), in the strawberry crop and consumes two‐spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae), and pollen as well. Augmentative biological control programs may fail if, following release, predators disperse from the crop. We studied the dispersal of O. insidiosus as a function of pollen availability, density of their main prey WFT, and the presence of the alternative prey TSSM, within and between strawberry plants. We found that O. insidiosus remained on the flowers during the 24 h of the assay. The dispersal of predators to a neighboring flower with thrips was approximately six times greater from a flower without pollen than from a flower with pollen. When TSSM was the only prey available, O. insidiosus colonized the leaves, and its dispersal within the plant was greater. At the plot scale, the predator dispersal from the release plant to other plants also depended on the presence of flowering plants and prey. Our results highlight the importance of flowering plants and pollen availability in enhancing the persistence of O. insidiosus in strawberry plants. Releases of this predator in the strawberry crop should be after the beginning of flowering, even at low WFT densities.

Phytochemical investigation and evaluation of acaricidal activity of Ammi crinitum Guss. Against the two-spotted spider mite Tetranychus urticae Koch

Ammi crinitum Guss., a species belonging to the Apiaceae family, is an exclusive and endemic plant of the Sicily region, Italy. Considering the limited scientific attention given to A. crinitum, herein, for the first time, metabolite profiles of polar extracts (MeOH) of the aerial parts, flowers, and roots were investigated by liquid chromatography coupled to electrospray ionization and high resolution multiple-stage mass spectrometry (LC-ESI/HRMSn), allowing the identification of 32 compounds, never identified in A. crinitum. Metabolites belonging to the classes of organic acids, megastigmanes, phenylpropanoids, iridoids, flavonoids, coumarins, triterpenoids, and polar lipids were putatively identified; in particular, several compoundsare reported here for the first time in Ammi genus. Considering the increasing interest for the development of botanical insecticides, the acaricidal activity of A. crinitum against the two-spotted spider mite Tetranychus urticae Koch was evaluated. Although all extracts showed promising acaricidal activity, the most effective was the extract obtained from the aerial parts. The lowest LD50 and LD90 values of 2.3 and 77.3 μg‧cm−2 were estimated for this extract from aerial parts, although this LD50 was statistically identical to the LD50 of the roots extract. The extract from aerial parts not only caused the mortality of T. urticae adults, but also inhibited the fertility and fecundity of females, even when a dose of 5 μg‧cm−2 was applied. Based on our experiments, MeOH extracts from aerial parts biomass of A. crinitum can be proposed as a perspective source of active substances of potential botanical acaricides.

Monitoring detoxification enzyme levels and resistance of Tetranychus urticae against some METI-group chemicals in Türkiye cotton fields.

Acaricides used against Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) in cotton fields cause control failure over time. To determine the resistance status of T. urticae populations to tebufenpyrad and bifenazate, different populations collected from Aydın (AYD), Adana (ADA), Şanlıurfa (SAN), and Diyarbakır (DIY) provinces of Türkiye, between 2019 and 2020, were subjected to diagnostic dose bioassays. Firstly, the spider mites were eliminated with a discriminating dose. Afterwards, LC50 and LC90 of the remaining populations were determined and the ten highest resistant populations were selected. The highest phenotypic resistance to bifenazate was observed in AYD4 and DIY2 (LC50 57.14 mg L- 1 with 85.01-fold and LC50 30.15 mg L- 1with 44.86-fold, respectively), while the lowest phenotypic resistance was found in SAN6 (LC50 1.5 mg L- 1; 2.28-fold). Considering the phenotypic resistance to tebufenpyrad, the highest resistance was found in AYD4 population (LC50 96.81 mg L- 1; 12.92-fold), while the lowest - in DIY28 population (LC50 21.23 mg L- 1; 2.83-fold). In pharmacokinetic studies, the ADA16 population was compared with the sensitive German Susceptible Strain population and it was determined that carboxylesterase activity was statistically higher (1.46 ± 0.04 nmol/min/mg protein enzyme activation 2.70-fold). The highest activation of glutathione S-transferase was detected in ADA16 (1.49 ± 0.01 nmol/min/mg protein; 2.32-fold). No mutations were found in PSST (METI 1), the point mutation site for tebufenpyrad, and Cytb (METI 3), the point mutation site for bifenazate. In terms of phenotypic resistance, bifenazate was found to be moderately resistant in two populations (85.01 and 44.86-fold), while tebufenpyrad was moderately resistant in one population (12.92-fold). This study showed that both acaricides are still effective against T. urticae populations.

Enhancing retinal fundus image classification through Active Gradient Deep Convolutional Neural Network and Red Spider Optimization

Enhancing retinal fundus image classification through Active Gradient Deep Convolutional Neural Network and Red Spider Optimization

The soybean plasma membrane GmDR1 protein conferring broad-spectrum disease and pest resistance regulates several receptor kinases and NLR proteins

Overexpression of Glycine max disease resistant 1 (GmDR1) exhibits broad-spectrum resistance against Fusarium virguliforme, Heterodera glycines (soybean cyst nematode), Tetranychus urticae (Koch) (spider mites), and Aphis glycines Matsumura (soybean aphids) in soybean. To understand the mechanisms of broad-spectrum immunity mediated by GmDR1, the transcriptomes of a strong and a weak GmDR1-overexpressor following treatment with chitin, a pathogen- and pest-associated molecular pattern (PAMP) common to these organisms, were investigated. The strong and weak GmDR1-overexpressors exhibited altered expression of 6098 and 992 genes, respectively, as compared to the nontransgenic control following chitin treatment. However, only 192 chitin- and 115 buffer-responsive genes exhibited over two-fold changes in expression levels in both strong and weak GmDR1-overexpressors as compared to the control. MapMan analysis of the 192 chitin-responsive genes revealed 64 biotic stress-related genes, of which 53 were induced and 11 repressed as compared to the control. The 53 chitin-induced genes include nine genes that encode receptor kinases, 13 encode nucleotide-binding leucine-rich repeat (NLR) receptor proteins, seven encode WRKY transcription factors, four ethylene response factors, and three MYB-like transcription factors. Investigation of a subset of these genes revealed three receptor protein kinases, seven NLR proteins, and one WRKY transcription factor genes that are induced following F. virguliforme and H. glycines infection. The integral plasma membrane GmDR1 protein most likely recognizes PAMPs including chitin and activates transcription of genes encoding receptor kinases, NLR proteins and defense-related genes. GmDR1 could be a pattern recognition receptor that regulates the expression of several NLRs for expression of PAMP-triggered immunity and/or priming the effector triggered immunity.

Sucking insect’s pest management in organic rose production

Sucking insects are the most common pests and could affect a wide range of cultural and wild plants. They possess a big reproductive potential and under favourable climatic conditions can cause considerable damages on agricultural crops. Some of the sucking insects show resistance to chemical pesticides, which additionally makes their control difficult. To investigate the effect of natural pesticides on the population of some sucking insects in a two year`s field experiment was conducted in the region of the village Kliment on five years`s old organic rose plantation. The following products have been included in the investigation: Limocide® (60 g/L orange oil) NeemAzal® T/S (Nime-substance – 2.5 %) and 4 % bee glue solution. The field experiments were arranged according to the block method in four replications and plot size of 18 м2 (21 plants per variant). The population density of sucking insects varied depending on the climate conditions. The product Limocide® and the 4% bee glue solution managed to control the invasion of the two-spotted spider mite Macrosiphum rosae L. and proved their effectiveness against Thrips tabaci as well. The product that contain as azadirachtin as an active substance showed an unsatisfactory percentage of effectiveness against the target insects. The 4% bee glue solution has a great potential, and its mechanism of action needs to be further investigated. Keywords: biological control, sucking insects, roses

First Report of Tetranychus truncatus Ehara (Acari: Tetranychidae) Infesting Groundnut (Arachis hypogaea L.) in India through Morphological and Molecular Insight

Background: Red spider mite, Tetranychus truncatus Ehara (Acari: Tetranychidae) infests many agriculture and horticulture crops in India, but to date it had not been found damaging cultivated groundnut. During 2022-23, the incidence of this species was high in many groundnut growing regions of Tamil Nadu. Identification of the species is highly essential for effective management of the particular pest. Hence, the aim of this research was to identify the mite species infesting groundnut crop and describe the damage caused. Methods: Survey was carried out all over Tamil Nadu and samples of mite infested groundnut leaves were collected from field based on damage symptoms, observed and examined under Stereo zoom microscope, microslides were prepared using Hoyer’s medium and taxonomic characters were studied under phase contrast microscope. Molecular analysis was done by genomic DNA isolation, PCR amplification, sequencing and BLAST performed to check the identity with GenBank Sequences. ITS2 primer was used. Result: Red spider mite species, T. truncatus was identified first time in groundnut through both morphological characters and molecular tools. Female: Idiosomal setae longer than the interval between their longitudinal bases and gradually tapers distally. Diamond- shaped pattern of striae between e1 and f1 setal bases. Tarsus I with 4 tactile setae proximal to proximal duplex setae. Male: Aedeagus with tiny terminal knob, apparently truncate with a slight indentation on the dorsal margin.

Indirect effects of plasma-activated water irrigation on Tetranychus urticae populations

AbstractPlasma-activated water (PAW) is receiving increased attention as a booster of seed germination and seedling vigor, and some studies have described use of PAW to manage crop pathogens. Here, we examined physicochemical properties of two PAWs (referred to as PAW 6.0 and 9.4 min with atmospheric plasma jet) and assessed “their indirect effects” (applied as supplementary irrigation) on host suitability of tomato plants (Solanum lycopersicum L.) to two-spotted spider mites (Tetranychus urticae Koch). Exposure of water to cold plasma significantly lowered pH and increased concentrations of H2O2, NO2−, and NO3−. Supplementary PAW irrigations elicited significant increases in leaf composition of several elements (N, P, K S, Ca, and Mg), leaf reflectance, plant size, and trichome densities (except non-glandular trichomes on the adaxial surface). Preference bioassays revealed significant avoidance of settling and reduced oviposition by two-spotted spider mites on leaf discs from PAW-irrigated plants compared to those from untreated control plants. Performance bioassays showed a significant decrease in two-spotted spider mite populations on PAW-irrigated plants. Results presented in this study provide comprehensive support to the hypothesis that indirect effects of supplementary PAW irrigation significantly reduce host plant suitability to two-spotted spider mites. PAW 6.0 may be slightly better than PAW 9.4, and this difference in performance is discussed in this study. Applications of PAW as supplementary irrigation are likely highly compatible with other IPM tactics and should be considered an innovative and sustainable component in twenty-first-century pest management.

Efficacy of Biopesticides Against <i>Tetranychus Urticae</i> Koch Infesting Dodi <i>Leptadenia Reticulata</i>

A field experiment was carried out to test the efficacy of biopesticides against the red two spotted spider mite Tetranychus urticae Koch infesting dodi (Jivanti), Leptadenia reticulata (Ret.) Wight and Aruott. The findings revealed that azadirachtin 0.15 EC was found most effective incidence (3.19/ cm2 leaf) followed by neemastra (3.27 mites/ cm2 leaf), neem oil (3.34 mites/ cm2 leaf) and neem seed kernal extract (3.42 mites/ cm2 leaf). Beauveria bassiana 5% WP (5.31 mites/ cm2 leaf), ashwagandha 7.5% leaf extract (5.37 mites/ cm2 leaf) and Metarhizium anisopliae 1.15% (5.53 mites/ cm2 leaf) were moderate in their effectiveness. Maximum incidence was noticed from the leaves treated with desi cow urine (5%).

Efficacy of Some Insecticides Aganist Fruit Borer <i>Helicoverpa Armigera</i> (Hübner) and Two Spotted Spider Mite <i>Tetranychus Urticae</i> (Koch) in Tomato

Fruit borer Helicoverpa armigera (Hübner) and two spotted spider mite, Tetranychus urticae (Koch) are destructive pests exerting a high crop loss in tomato. The field experiment was carried out to evaluate the efficacy of some insecticides and acaricides against H. armigera and T. urticae at College of Agriculture, Vijayapura. The results revealed that chlorantraniliprole 18.5% SC @ 0.15 ml/ l followed by spiromesifen 22.9% SC @ 0.5 ml/ l was recorded lowest fruit borer larvae (1.25/ plant). The treatment chlorantraniliprole 18.5% SC @ 0.15 ml/ l recorded lowest fruit damage (8.91/ plant) at 15 DAS. The treatment spiromesifen 22.9% SC @ 0.5 ml/ l recorded lowest number of two spotted spider mites (2.30/ square inch of leaf area) at 15 DAS. The combination treatment of chlorantraniliprole 18.5% SC @ 0.15 ml/ l followed by spiromesifen 22.9% SC @ 0.5 ml/ l found most effective treatment to control both the above pests on tomato.

Metabolomic responses of tea [Camellia sinensis (L.) O. Kuntze] leaves to red spider mite [Oligonychus coffeae (Nietner)] and tea mosquito bug [Helopeltis theivora Waterhouse] infestation: a GC–MS-based study

BackgroundThe tea plant, Camellia sinensis (L.) O. Kuntze, is an evergreen leafy plant whose tender leaves are used in the manufacturing of the world’s second most consumed beverage—tea. The production and consumption of tea worldwide have continually increased over the decades. All parts of the plant—leaf, stem, root, flower and seed, are fed upon by insect pests. This study elucidates the metabolomic changes occurring in tea leaves in response to infestation by two major pests in tea gardens: red spider mites and tea mosquito bugs. These pests significantly impact both the quantity and quality of tea production. The secondary metabolites produced by the tea due to pest attack has been analysed using GC–MS analysis in the laboratory.ResultsMostly fatty acid derivatives were biosynthesized as secondary metabolites due to pest attack as revealed from the result. In both infestations, methyl stearate was found to be produced along with increased chromatographic peaks of compounds such as caffeine, methyl palmitate, methyl linoleate, and stigmasta-7,25-dien-3-ol. In comparison with respective control samples (leaf with no pest attack), the one attacked by red spider mite showed eighteen exclusive metabolites, whereas tea mosquito bug infested leaf showed six such exclusive metabolites.ConclusionsSome metabolites were found to be either increased or decreased in their amount in both the samples. The increased compounds were reported with insecticidal and pesticidal properties with respect to respective controls. Some metabolites were markers of pest attacks i.e. plant defense mechanism induced phytochemicals according to the literature as discussed in this research.