Mite Populations Research Articles

1576 Increased demodex mite population is involved with the cutaneous neurogenic inflammation in rosacea by upregulation of TRPV1 by NGF-TrkA activation

1576 Increased demodex mite population is involved with the cutaneous neurogenic inflammation in rosacea by upregulation of TRPV1 by NGF-TrkA activation

Enhanced mite grazing leads to pattern shifts in soil N2O emissions after organic fertilizer application

Studies have reported inconsistent (or even opposing) effects of soil mesofauna, such as mites, on net soil N2O emissions. Here we show that whether mites affect net N2O emissions positively, negatively, or neutrally depends on the microbial guild that dominates the emissions. We found that enhanced mite grazing, following artificially elevated mite populations, led to shifts in N2O emission patterns in soils applied with organic fertilizer: N2O emissions decreased under low soil moisture conditions, whereas those under high soil moisture conditions increased. Since the dominant microbial processes underlying N2O emissions shift from fungal to bacterial denitrification with increasing soil moisture, our results imply that enhanced mite grazing tends to decrease net soil N2O emissions dominated by fungi, whereas increase those dominated by bacteria. Furthermore, we observed that mite grazing largely suppressed fungal mycelial growth after organic fertilizer application but promoted the dispersal and decomposition of fertilizer granules and N mineralization. These findings suggested that the distinct effect of enhanced mite grazing on N2O emissions dominated by fungi and bacteria could occur because high-intensity mite grazing affects fungi-derived N2O emissions mainly by consuming the biomass of N2O-producing fungi, which has a negative effect, whereas affects bacteria-derived N2O emissions mainly by stimulating bacterial N2O-producing processes via the promotion of N diffusion from the fertilizer to the soil, which has a positive effect.

Efficacy of entomopathogen Cordyceps tenuipes (Peck) Kepler, B. Shrestha et Spatafora against spider mite Tetranychus piercei McGregor (Acari: Tetranychidae)

ABSTRACT Tetranychus piercei (Acari: Tetranychidae) is a spider mite that infests a wide range of plants. It is difficult to control due to its ability to quickly develop resistance to common pesticides. The study aimed to find the effect of relative humidity (55, 75, and 95 ± 2% RH) on the efficacy of the entomopathogen Cordyceps tenuipes (1 × 106, 1 × 107 and 1 × 108 conidia/ml) against the egg and adult female stages of T. piercei. The results showed that the mortality of T. piercei eggs was concentration-dependent and that RH has a synergistic effect on efficacy. The egg mortality increased with the increasing the concentration from 1 × 106 to 1 × 108 conidia/ml at the same RH condition, and it was significantly higher at 1 × 108 conidia/ml at 95% RH than at 75 and 55% RHs. The median lethal time (LT50) for adult females was 41.1 hours at 95% RH and 49.8 hours at 75% RH when treated with a concentration of 1 × 108 conidia/ml. This was significantly lower than the LT50 values at other relative humidity levels and concentrations. The results of the study on potted bean plants showed that double spray of C. tenuipes was effective in controlling T. piercei infestations at a concentration of 1 × 108 conidia/ml. With a single spray of C. tenuipes, the mite population tends to be reduced initially and then increased subsequently. Thus, considering RH and incorporating other strategies is important when using biological control methods to effectively control this pest.

Mode of dispersal of the sugarcane rust mite (Abacarus sacchari) in the sugarcane field

ABSTRACT The sugarcane rust mite (SRM), Abacarus sacchari, infests sugarcane in the Everglades Agricultural Area in southern Florida. Reddish-brown symptoms associated with SRM feeding on leaves appear in April and reach their peak in August-September. Mite dispersal plays an important role in habitat colonization. However, SRM dispersal in sugarcane fields has not yet been explored because of its microscopic size. This study aimed to determine the role of aerial dispersal in the colonization of sugarcane fields. Mite dispersal was studied by measuring aerial mites and mite population on the sugarcane canopy with the elimination of possible ambulatory movement among plants. In addition, the potential dispersal using ambulatory movement as well as precipitation was also investigated. The result suggests that aerial dispersal was the most important method for SRM dispersal. Moreover, females predominated airborne mites, comprising approximately 90% of those measured with 60% gravidity. This strong female bias and its high gravidity in airborne mites further demonstrate the potential role of aerial dispersal in the colonization of sugarcane fields.

From laboratory to field: laboratory-measured pesticide resistance reflects outcomes of field-based control in the redlegged earth mite, Halotydeus destructor

Resistance to pesticides is typically identified via laboratory bioassays after field control failures are observed, but the results of such assays are rarely validated through experiments under field conditions. Such validation is particularly important when only a low-to-moderate level of resistance is detected in the laboratory. Here we undertake such a validation for organophosphate resistance in the agricultural pest mite Halotydeus destructor, in which low-to-moderate levels of resistance to organophosphorus pesticides have evolved in Australia. Using data from laboratory bioassays, we show that resistance to the organophosphate chlorpyrifos is higher (around 100-fold) than resistance to another organophosphate, omethoate (around 7-fold). In field trials, both these chemicals were found to effectively control pesticide-susceptible populations of H. destructor. However, when applied to a resistant mite population in the field, the effectiveness of chlorpyrifos was substantially decreased. In contrast, omethoate remained effective when tested alone or as a mixture with chlorpyrifos. We also show that two novel (non-pesticide) treatments, molasses and wood vinegar, are ineffective in controlling H. destructor when sprayed to pasture fields at rates of 4 L/ha. These findings suggest a close link between levels of resistance quantified through laboratory bioassays and the field effectiveness of pesticides; however, in the case of H. destructor, this does not necessarily mean all field populations possessing organophosphate resistance will respond similarly given the potentially complex nature of the underlying resistance mechanism(s).

Detecting two-spotted spider mites and predatory mites in strawberry using deep learning

Strawberries are an important and high-value crop in the United States. The total value of strawberry production in the United States was $3.42 billion in 2021. However, a major pest of strawberries, two-spotted spider mites (TSSM) (Tetranychus urticae Koch), can cause severe economic losses due to mites feeding on chlorophyll which interferes with photosynthesis. Predatory mites (Neoseiulus californicus and Phytoseiulus persimilis) can control TSSM populations and provide an alternative to conventional pesticides. Predatory mites are more friendly to the environment than pesticides. To monitor TSSM and predatory mite populations in the field, frequent sampling is required. However, manual counting of mites using a hand lens is challenging for a large field. Therefore, this study applied deep learning models to detect TSSM and predatory mites in strawberries from smartphone images. Three different smartphones (Motorola Moto E5 Play, OnePlus A5000, and iPhone XR) and a 25x macro lens were used to collect a total of 3,013 images, including 1,779 TSSM images and 1,234 predatory mite images. TSSM images were collected by the three smartphones, and only the OnePlus A5000 and iPhone XR were used to collect predatory mite images that only contained predatory mites or contained both predatory mites and TSSM in the same image. TSSM images were used to compare two deep learning models (YOLOv4 and Faster R-CNN Resnet50) and three different smartphone cameras. This study found that the average detection accuracy of YOLOv4 and Faster R-CNN was 0.935 and 0.863, respectively. Deep learning models achieved the best detection accuracy on the image collected by iPhone XR. The YOLOv4 model was trained to compare the detection performance of three different input image sizes (160 × 160, 320 × 320, 640 × 640 pixels) for TSSM and predatory mite detection. This study found that the mean average precision of the YOLOv4 increased as the image size increased, and the model trained with an image size of 640 × 640 pixels achieved the detection accuracy of 0.933 for TSSM and predatory mites. This study also found that the YOLOv4 could detect pests under different field illumination conditions. The smartphone image-based method can detect the TSSM and predatory mites quickly from images and with high detection accuracy, which can help growers use less time to monitor mite populations in the field.

Intraspecific diversity in the mechanisms underlying abamectin resistance in a cosmopolitan pest.

Pesticide resistance relies on a myriad of mechanisms, ranging from single mutations to a complex and polygenic architecture, and it involves mechanisms such as target-site insensitivity, metabolic detoxification, or a combination of these, with either additive or synergistic effects. Several resistance mechanisms against abamectin, a macrocyclic lactone widely used in crop protection, have been reported in the cosmopolitan pest Tetranychus urticae. However, it has been shown that a single mechanism cannot account for the high levels of abamectin resistance found across different mite populations. Here, we used experimental evolution combined with bulked segregant analyses to map quantitative trait loci (QTL) associated with abamectin resistance in two genetically unrelated populations of T. urticae. In these two independent QTL mapping experiments, three and four QTLs were identified, of which three were shared between experiments. Shared QTLs contained genes encoding subunits of the glutamate-gated chloride channel (GluCl) and harboured previously reported mutations, including G314D in GluCl1 and G326E in GluCl3, but also novel resistance candidate loci, including DNA helicases and chemosensory receptors. Surprisingly, the fourth QTL, present only in only one of the experiments and thus unique for one resistant parental line, revealed a non-functional variant of GluCl2, suggesting gene knock-out as resistance mechanism. Our study uncovers the complex basis of abamectin resistance, and it highlights the intraspecific diversity of genetic mechanisms underlying resistance in a cosmopolitan pest.

Using targeted sequencing and TaqMan approaches to detect acaricide (bifenthrin, bifenazate, and etoxazole) resistance associated SNPs in Tetranychus urticae collected from peppermint fields and hop yards.

Tetranychus urticae (Koch) is an economically important pest of many agricultural commodities world-wide. Multiple acaricides, including bifenazate, bifenthrin, and extoxazole, are currently registered to control T. urticae. However, populations of T. urticae in many different growing regions have developed acaricide resistance through multiple mechanisms. Within T. urticae, single nucleotide polymorphisms (SNPs) have been documented in different genes which are associated with acaricide resistance phenotypes. The detection of these mutations through TaqMan qPCR has been suggested as a practical, quick, and reliable tool to inform agricultural producers of acaricide resistance phenotypes present within their fields and have potential utility for making appropriate acaricide application and integrated pest management decisions. Within this investigation we examined the use of a TaqMan qPCR-based approach to determine genotypes which have been previously associated with acaricide resistance in field-collected populations of T. urticae from peppermint fields and hop yards in the Pacific Northwest of the United States and confirmed the results with a multiplex targeted sequencing. The results suggest that a TaqMan qPCR approach accurately genotypes T. urticae populations for SNPs that have been linked to Bifenazate, Bifenthrin, and Etoxazole resistance. The results also demonstrated that different populations of mites in Washington and Idaho displayed varying frequencies of the examined SNPs. While we were able to detect the SNPs associated with the examined acaricides, the mutation G126S was not an appropriate or accurate indicator for bifenazate resistance.

Fitness costs of pyrethroid resistance in the polyphagous pest mite, Halotydeus destructor, under field conditions

The redlegged earth mite, Halotydeus destructor, is an economically important pest of winter field crops and pastures in Australia, and has evolved field resistance to pyrethroid chemicals through a polymorphism in the voltage-gated parasodium channel leading to knockdown resistance (kdr). In this study, we quantified the rate of reversion to susceptibility of partially resistant H. destructor populations under field conditions in the absence of pesticide exposure. This was conducted over multiple years at two geographically distant locations with mite populations known to possess pyrethroid resistance. Fitness costs associated with pyrethroid resistance were identified through reductions in the frequency of kdr resistance alleles in the absence of pesticides. This was assessed using an amplicon sequencing approach targeting known resistance alleles. We also found that resistance can increase rapidly in frequency after only a single pyrethroid application in the field. Our results highlight that, once established in H. destructor populations, pyrethroid resistance will not easily be lost even after several years, emphasizing the importance of limiting the evolution of resistance in the first place. This helps to explain why pyrethroid resistance in H. destructor continues to persist at very high frequencies in the field and continues to expand within Australia despite the existence of fitness costs. Understanding field fitness costs associated with pesticide resistance is important when devising resistance management strategies for this pest.

Management of Panonychus ulmi with Various Miticides and Insecticides and Their Toxicity to Predatory Mites Conserved for Biological Mite Control in Eastern U.S. Apple Orchards

Panonychus ulmi (Koch) (Acari: Tetranychidae), commonly known as European red mite, is a polyphagous pest of various tree and small fruit crops, including apples. A field study was conducted to evaluate different pesticide options available for the management of P. ulmi, and their impact on the population of non-target predatory mite species complex consisting of Neoseiulus fallacis, Typhlodromus pyri, and Zetzellia mali in apple orchards. Pesticides were applied using a commercial airblast sprayer at the 3-5 mite/leaf recommended economic Integrated Pest Management (IPM) threshold or prophylactically in the spring ignoring IPM practices such as monitoring, reliance on biological control and economic thresholds. Effects on the motile and egg stages of P. ulmi were evaluated as were effects on the populations of predatory mites through frequent leaf counts during the season. We also recorded the subsequent overwintering eggs of P. ulmi from each pesticide treatment. The two prophylactic treatments containing a mixture of zeta-cypermethrin + avermectin B1 + 1% horticultural oil and abamectin + 1% horticultural oil provided effective control of P. ulmi population throughout the season without reducing predatory mite populations. In contrast, eight treatments applied at the recommended economic threshold of 3-5 mites/leaf were not effective in suppressing P. ulmi populations and most reduced predatory mites. Etoxazole had significantly higher number of overwintering P. ulmi eggs compared to all other treatments.

Economic Impact of the Persea Mite in Spanish Avocado Crops

The Persea mite, Oligonychus perseae Tuttle, Baker & Abbatiello (Acari: Tetranychidae), is an economically important foliar pest of avocados in Spain. The effects of this mite on the foliar damage, production losses and economic impact were assessed in two avocado, cv. Hass, orchards located in the main growing areas of Spain (Northern Tenerife and Málaga) for 3 and 5 consecutive years, respectively. The economic injury level (EIL) for the optimization of the use of acaricides to control this mite was also established, considering three spraying strategies: (i) mite-free treatment (<50 mites per leaf), (ii) conventional treatment (50–150 mites per leaf), and (iii) control treatment (the absence of spraying). Persea mite populations were sampled fortnightly and foliar damage was estimated. At the end of each season, fruits were harvested, weighed and production losses were quantified. The cumulate mite-days (CMDs) had a significant effect on the percentage of leaf area damaged (PLAD) and yield reduction. High numbers of the Persea mite caused extensive damage to leaves, so a loss in tree yield was evident. However, for the middle population level, there was no evidence of yield losses. The quantitative EIL was estimated at a PLAD of 17%, equivalent to a CMDs of 178 mites per leaf, which is the amount of damage that should not be exceeded. In Northern Tenerife, with a mild climate, the Persea mite can reach significant populations that are maintained throughout the months. In avocado orchards in Málaga, the summer is hotter and drier, so the presence of the mite exists for a shorter duration in the seasons, with less damage to the leaves. In Tenerife, yield loss can be compensated by chemical treatments that permit pest control.

Plant-Mediated Effects of Beneficial Microbes and a Plant Strengthener against Spider Mites in Tomato.

The two-spotted spider mite Tetranychus urticae is a polyphagous herbivore with a worldwide distribution, and is a serious pest in tomato and other crops. As an alternative to chemical pesticides, biological control with the release of natural enemies such as predatory mites represent an efficient method to control T. urticae in many crops, but not in tomato. Other biological control agents, such as beneficial microbes, as well as chemical compounds, which can act as plant defense elicitors that confer plant resistance against pests and pathogens, may prove promising biological solutions for the suppression of spider mite populations in tomato. Here, we assessed this hypothesis by recording the effects of a series of fungal and bacterial strains and the plant strengthener acibenzolar-s-methyl for their plant-mediated effects on T. urticae performance in two tomato cultivars. We found significant negative effects on the survival, egg production and spider mite feeding damage on plants inoculated with microbes or treated with the plant strengthener as compared to the control plants. Our results highlight the potential of beneficial microbes and plant strengtheners in spider mite suppression in addition to plant disease control.

A survey of UK beekeeper's Varroa treatment habits.

The global spread of the parasitic mite Varroa destructor instigated a substantial decline in both managed and feral honeybee (Apis mellifera) colonies mainly across the Northern hemisphere. In response, many beekeepers began to treat their colonies with chemical acaricides to control mite populations in managed colonies. However, some countries or beekeepers allowed their bees to develop mite-resistance by adopting a "treatment-free" approach, rather than using selective breeding programs. Yet, the distribution and proportion of beekeepers either treating or not within the United Kingdom (UK) is unknown, as it is in most Northern hemisphere countries. Therefore, the aim of this study was to conduct a beekeeper survey to determine the current treatment strategies within the UK. We gathered 2,872 beekeeper responses from an estimated 30,000 UK beekeepers belonging to 242 bee-associations in the winter of 2020/21. The survey indicated that the majority (72-79%) of UK beekeepers are still treating their bees for Varroa, typically twice-yearly using chemical-based methods. Six percent or 1,800 UK beekeepers were treatment-free for six years or more. This is reflected by our finding that 78 associations out of 242 consist of responders who entirely treated, while only four associations had more than 75% of their members that were non-treating. Overall treatment status was not affected by association currently. Using the baseline data from this survey it will be possible in the future to observer if a shift towards treatment-free beekeeping occurs or not.

Comparative assessment of different ivermectin and doramectin formulations for mange control in grazing steers

Psoroptic mange causes relevant losses of productivity in cattle. Macrocyclic lactones are one of the main pharmacological tools recommended for controlling it. The aim of the current work was to compare the relationship between the pharmacokinetic behavior and the effectiveness of both ivermectin (IVM) and doramectin (DRM) following their administration as either the traditional (1 %) or long-acting (3.15–3.5 %) injectable formulations to cattle naturally infected with Psoroptes ovis. The overall work involved three trials (1, 2 and 3) carried out on commercial beef cattle farms (grazing systems). In Trial 1, 20 grazing steers with active mange infection were allocated into 2 groups (n = 10) and treated subcutaneously (SC) with either IVM (1 %) or DRM (1%) at 0.2 mg/kg. In Trial 2, 16 grazing steers with active mange divided in 2 groups (n = 8) were treated SC with either IVM 1 % (0.2 mg/kg) or IVM 3.15 % long-acting (0.63 mg/kg). In Trial 3, 2 groups of mange infected steers (n = 8) were treated SC with either IVM 3.15 % (0.63 mg/kg) or DRM 3.5 % (0.7 mg/kg). Blood samples were collected of each experimental group and the drug systemic availability was estimated by measuring of IVM/DRM concentrations by HPLC. Skin scraping samples were collected from each animal and mites were counted at 14, 21 and 28 days post-treatment. In Trial 1, the mite density score on day 14 was significantly lower for DRM (0.60) compared to IVM (1.80) (P = 0.019). Based on the number of animals clinically cured (negative to the presence of mites), the efficacy of DRM was higher (80 %) than that obtained for IVM (10 %) (P < 0.05). DRM systemic exposure measured as AUC was 1.37-fold higher compared to IVM. In Trial 2, even though IVM exposure was significantly greater after the long-acting (3.15 %) compared to the traditional formulation (1 %), none of the treatments significantly reduced the mite density score, with a percentage of animals cured between 0 % and 37.5 % after both IVM treatments. In Trial 3, the 100 % of cured animals were achieved at day 21 (IVM 3.15 %) and at day 28 (DRM 3.5 %) post-treatment. In conclusion, DRM treatment could offer some therapeutic advantages in field situations where IVM fails to control mange. Depending on the level of susceptibility of the mite population, long-acting pharmaceutical formulations can be useful to control Psoroptic mange in cattle. The use of macrocyclic lactones for mange control in cattle should be based on appropriate diagnosis on each individual farm.

Genetic analysis of the tomato russet mite provides evidence of oligophagy and a widespread pestiferous haplotype.

Worldwide, the tomato russet mite (TRM), Aculops lycopersici (Eriophyidae), is a key pest on cultivated tomato in addition to infesting other cultivated and wild Solanaceae; however, basic information on TRM supporting effective control strategies is still lacking, mainly regarding its taxonomic status and genetic diversity and structure. As A. lycopersici is reported on different species and genera of host plants, populations associated with different host plants may constitute specialized cryptic species, as shown for other eriophyids previously considered generalists. The main aims of this study were to (i) confirm the TRM taxonomic unity of populations from different host plants and localities as well as the species' oligophagy, and (ii) to advance the understanding of TRM host relationship and invasion history. For this purpose, we evaluated the genetic variability and structure of populations from different host plants along crucial areas of occurrence, including the area of potential origin, based on DNA sequences of mitochondrial (cytochrome c oxidase subunit I) and nuclear (internal transcribed spacer, D2 28S) genomic regions. Specimens from South America (Brazil) and Europe (France, Italy, Poland, The Netherlands) were collected from tomato and other solanaceous species from the genera Solanum and Physalis. Final TRM datasets were composed of 101, 82 and 50 sequences from the COI (672bp), ITS (553bp) and D2 (605bp) regions, respectively. Distributions and frequencies of haplotypes (COI) and genotypes (D2 and ITS1) were inferred; pairwise genetic distance comparisons, and phylogenetic analysis were performed, including Bayesian Inference (BI) combined analysis. Our results showed that genetic divergences for mitochondrial and nuclear genomic regions from TRM associated with different host plants were lower than those observed in other eriophyid taxa, confirming conspecificity of TRM populations and oligophagy of this eriophyid mite. Four haplotypes (cH) were identified from the COI sequences with cH1 being the most frequent, representing 90% of all sequences occurring in all host plants studied (Brazil, France, The Netherlands); the other haplotypes were present exclusively in Brazilian populations. Six variants (I) were identified from the ITS sequences: I-1 was the most frequent (76.5% of all sequences), spread in all countries and associated with all host plants, except S. nigrum. Just one D2 sequence variant was found in all studied countries. The genetic homogeneity among populations highlights the occurrence of a highly invasive and oligophagous haplotype. These results failed to corroborate the hypothesis that differential symptomatology or damage intensity among tomato varieties and solanaceous host plants could be due to the genetic diversity of the associated mite populations. The genetic evidence, along with the history of spread of cultivated tomato, corroborates the hypothesis of a South American origin of TRM.

A Novel Approach to Tally Aculops cannabicola (Acari: Eriophyidae) for Field and Laboratory Studies.

The hemp russet mite, Aculops cannabicola (Farkas) is a key pest of hemp (Cannabis sativa L.). Given its microscopic size, estimating the size of its populations can be a major limitation to control this pest. Here, we describe a method to count A. cannabicola using photographs taken with a handheld digital microscope. We compared the consistency and strength of the relationship between photographic- and microscope-based counts of mites from infested plants. Among the three sections of the leaflet, the maximum consistency levels were observed in the proximal (50%) and middle photographs (50%). However, it reached from 64% to 100% when the three sections were considered. Photographic and a microscope-based counts were positively correlated (>0.7). A single photograph can be a good predictor of the total mites per leaflet, however, using two pictures (proximal and middle sections) will increase the consistency of the abundance of A. cannabicola per leaflet. A minimum of 22 leaflets per sampling event can support a strong correlation between the microscope and photographic counts. Our method requires low budget and training and takes short time (0.4 to 1.3 min per leaflet) to count mites per sample. Additionally, photographs can be stored on a smartphone, computer, or tablet, allowing users to share, store and process the photos. This method simplifies counts of A. cannabicola on hemp for research purposes and provides a practical tool for growers to assess mite populations for management decisions. In addition, it may be useful for monitoring eriophyid mites on cultivated plants.

Enhancement of bioefficacy of insecticides on spray tank mixing with Wetcit surfactant on chilli crop

The compatibility and effectiveness of Wetcit surfactant using as spray tank mix with insecticide formulations against mites (Polyphagotarsonemus latus) on Chilli crop was evaluated. The treatments were taken as Propargite 57% EC @ 1500 ml/ha, Emamectin benzoate 5% SG @ 200 g/ha and Buprofezin 25% SC @ 300 ml/ha alone, and as tank mix with Wetcit @ 500 ml/ha at their lower dose rate 1350 ml/ha, 180 g/ha and 270 ml/ha, respectively. Wetcit alone @ 500 ml/ha and untreated control (water alone) treatments were also taken for comparison. The mite population recorded at 5, 10 and 15 days after each spray showed that Wetcit used with insecticidal formulations resulted in low mite population than sole insecticidal treatments (without mixing with surfactant). Thus Wetcit @ 500 ml/ha used with Propargite 57% EC @ 1350 and 1500 ml/ha, Emamectin benzoate 5% SG @ 180 and 200 g/ha and Buprofezin 25% SC @ 200 and 300 ml/ha resulted to be effective with low mite population at each observation time and increased chilli fruit yield. No phytotoxicity to chilli crop was observed at each observation time. Thus, Wetcit surfactant was compatible with tested insecticide formulations and enhanced their effectiveness against mites in chilli crop.

Eco-friendly management of two spotted spider mite, Tetranychus urticae (Koch) in Brinjal

The effect of the application of acaropathogenic fungi viz., Beauveria bassiana, Nomuraea anisopliae, Lecanicillium lecanii, Hirsutella thompsonii and biopesticides viz., azadirachtin 1500 ppm, azadirachtin 3000 ppm, azadirachtin 10000 ppm and Fortified Neem oil were tested with synthetic acaricides like Propargite and Fenazaquin against two-spotted spider mite (Tetranychus urticae). The result of evaluation of acaropathogenic fungi revealed that low mite population of 5.68 nos/2cm2 was observed in Fenazaquin 10 EC @ 1.5ml/l applied plot with 69.78% reduction in mite population followed by Propargite and Nomuraea anisopliae treated plots and the result of evaluation of botanicals revealed that the application of Azadiractin 10000 ppm @ 2 ml/l resulted in low mite population of 6.75 nos /2 cm2 with 64.11% reduction over control. Therefore, the present investigation outlines the efficacy of plant extracts and acaropathogenic fungi as bio pesticide to display toxicity against two-spotted spider mite on brinjal increasing in yield and avoid environmental pollution and consumer health hazards.

Plantas de cobertura com potencial de reduzir a população do ácaro-rajado na soja

Abstract The objective of this work was to evaluate the potential of cover plants in reducing the population of the two-spotted spider mite, Te t r a n y c h u s urticae, in soybean. Seven host plants – cotton (Gossypium hirsutum), Urochloa ruziziensis, crotalaria (Crotalaria juncea), corn (Zea mays), radish (Raphanus sativus), soybean (Glycine max), and sorghum (Sorghum bicolor) – were evaluated for their effect on T. urticae biological parameters (oviposition, development stages, and survival) and preference for volatile odors (using a Y-tube olfactometer). Tetranychus urticae preferred cotton and showed a higher population growth rate on this host plant. The survival and oviposition of T. urticae was prolonged in radish and crotalaria plants, whereas juveniles did not complete their immature development on U. ruziziensis leaves. No preference was observed between the volatile odors of U. ruziziensis, radish, and crotalaria. Urochloa ruziziensis can reduce T. urticae populations in soybean plants.

Effect of Biotic and abiotic factors on mites infestation under grain storage- A review

Mites are common pests of stored grain containing high fat and protein content. They are considered secondary invaders among the diverse range of storage pests because they are unable to infest sound grain and instead feed on fractured kernels, debris, and high moisture grain that has been already damaged by some insect pests. The high humidity and optimum temperature are determining factors for the sensitivity of the food grains for mites attack. Mites directly risk human health by contaminating food and indirectly by mycotoxin released under storage conditions. They also result in a considerable loss in grain weight and a reduction in germination ability. The losses become more severe as the mite population grows. Chemical agents have traditionally been used to prevent or manage mite infestations, as it is the simplest and most cost-effective approach to dealing with stored grain mites. This review paper discusses Distribution, pest status, host range, food grain choice, abiotic factor influence, quantitative damage, change in biochemical composition, and botanicals for mite management.