Mite Populations Research Articles

The Impact of Microbial and Botanical Insecticides on Grape Berry Moths and Their Effects on Secondary Pests and Beneficials

According to the European Directive 2009/128/EC and the subsequent provisions activated in member states, conventional pesticides should be progressively replaced by “non-chemical tools and/or measures”. The identification of reliable alternatives to pesticides is crucial to achieve this objective. A European project (PURE) was funded to investigate this topic with reference to annual and perennial crops. In this framework, a number of natural insecticides, in particular microbial and botanical ones (Bacillus thuringiensis ssp. kurstaki, Beauveria bassiana, azadirachtin, pyrethrins and spinosad) were selected to test their effectiveness against grape berry moths, the key pests in most European vineyards. Trials were conducted in 2011 and 2012 in two experimental vineyards located in Italy (Tuscany and Veneto regions), following a randomized block design. Additional investigations were carried out in the Veneto region during 2013. Trial results stressed the high performance of spinosad and B. thuringiensis in controlling berry moth densities and the related damage. The use of B. bassiana mixed with B. thuringiensis did not significantly improve the impact of B. thuringiensis alone. Azadirachtin, and especially pyrethrins, proved to be less effective on berry moths than previous insecticides. The use of selected insecticides caused side-effects on a number of secondary pests, in particular leafhoppers. In 2011, densities of Empoasca vitis were higher in spinosad-treated plots probably because of a reduced egg parasitization rate. One year later, the population density of Zygina rhamni was higher in the plots treated with spinosad or pyrethrins. This trend was confirmed on spinosad-treated plots in the last experimental year. At the same time, spinosad and pyrethrins significantly reduced the predatory mite populations compared to other treatments. The use of these insecticides in viticulture is discussed in the framework of organic viticulture and Integrated Pest Management (IPM).

Seasonal incidence of major pest of chilli and their natural enemies under Western Vidharbha condition

Seasonal incidences of major pests of chilli viz., thrips, aphid, mites and fruit borer with natural enemies such as lady bird beetle, spider etc. were studied at Agriculture Research Station, Achalpur (Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola) during Kharif 2018-19 and 2019-20. The results of two years study revealed that the aphid population was observed from 33rd MW (0.28 and 3.20, respectively) throughout the whole growing season for both the year and it attained its initial peak during 44th and 45th MW, respectively. During the low rainfall year non significant positive correlation (0.410) was recorded. However, in next year significantly higher and positive (0.645) correlation was recorded with rainfall. The maximum population of thrips was observed at 39th MW (6.20 per leaf) and 44th MW (10.30 per leaf), the correlation between thrips population and rainfall was positively non-significant (0.389 and 0.033) for Kharif 2018 and 2019, respectively. The mites population were reached at its peak during 39th MW (2.70 per leaf) and 40th MW (2.15 per leaf) during both the year, respectively. The correlation studies for both the years revealed that, the mite’s population showed positively non-significant correlation with rainfall. The incidences of fruit borer commenced from 38th and 37th i.e. 0.80 per larvae per plant for both the year. The fruit borer population exhibited a negative non significant correlation with rainfall during Kharif 2018 and vice-versa during Kharif 2019. The lady bird beetle population was commenced from 31st with a mean population 0.30 per plant in Kharif 2018 and 0.10 per plant in Kharif 2019. The correlation studies between the population of lady bird beetle and rainfall was negatively non-significant for both the seasons. In case of spider, it attained its peak during 37th and 50th (0.40 and 0.60 per plant), respectively for both the season. The correlation studies between spider and rainfall were revealed that the population was negatively non-significant with rainfall during Kharif 2018 and 2019.

Spatial distribution and fluctuating populations of predatory mites (Mesostigmata: Phytoseiidae), phytophagous mites (Acari: Eriophyidae, Tetranychidae) and their relationships with wild chili pepper phenological stages in two Natural Protected Areas of Mexico

Ecological interactions between mites (predatory and phytophagous) and wild plants growing in undisturbed environments play a crucial role to understand their natural settlement, development and dispersion patterns. Pequin chili pepper, Capsicum annuum L. var. glabriusculum, is a low-cost natural resource for local communities living inside Natural Protected Areas (ANP) of Tamaulipas State in Mexico. The aims of this research work were: 1) determine the spatial distribution pattern of predatory and phytophagous mites, 2) determine the spatiotemporal association between predatory and phytophagous mites, and 3) determine the association among different mite species and some phenological stages of Pequin chili pepper. The most abundant phytophagous mites were Tetranychus merganser and Aculops lycpoersici, and the predatory species were Amblyseius similoides, Euseius mesembrinus and Metaseiulus (Metaseiulus) negundinis. Most mite species showed an aggregated distribution pattern according to the plant phenological stages. However, the distribution of mite species throughout time showed different types of aggregation. On the other hand, we found positive associations among A. lycopersici and T. merganser phytophagous mites with A. similoides, E. mesembrinus and M. (M.) negundinis predators mites. The association between plants and mite species were influenced by the phenological stages of Pequin chili pepper. This is an indication of the complexity among trophic-chain interactions that depend largely on the available resources and competition. These two factors serve as foundations for settlement, development and dispersion patterns of certain species.

Six-spotted mite and its predators on sprayed and unsprayed ‘Hass’ avocado trees

ABSTRACT Six-spotted mite, Eotetranychus sexmaculatus (Riley), is an introduced pest of ‘Hass’ avocados in New Zealand. Avocado orchards were surveyed for six-spotted mite and its natural enemies during 2016–18. Mean counts of six-spotted mite differed when compared by year. For each year, the effect of not spraying or spraying according to an integrated pest management programme (AvoGreen®) was not consistent for most location and season combinations. When year was ignored and all locations considered together, the leaves of unsprayed trees had fewer six-spotted mites than those of sprayed trees during autumn/winter. The phenology of mites and their predators in relation to leaf abscission was also determined on unsprayed potted trees during 2018–20 at two sites. Defoliation occurred in October and November each year but the association with densities of six-spotted mites was not consistent. Four species of phytoseiid mite predators were identified on orchards and potted trees with the most common species being Amblyseius herbicolus. The coccinellid mite predators Stethorus bifidus and S. histrio occurred on potted trees. The evidence that predators were able to control six-spotted mite populations was somewhat equivocal. Trials comparing sprayed and unsprayed trees under the same nutrient management and during multiple seasons would be useful.

Plant Growth-Promoting Rhizobacteria Enhance Defense of Strawberry Plants Against Spider Mites.

Plants mediate interactions between below- and above-ground microbial and animal communities. Microbial communities of the rhizosphere commonly include mutualistic symbionts such as mycorrhizal fungi, rhizobia and free-living plant growth-promoting rhizobacteria (PGPR) that may influence plant growth and/or its defense system against aboveground pathogens and herbivores. Here, we scrutinized the effects of three PGPR, Azotobacter chroococcum, Azospirillum brasilense, and Pseudomonas brassicacearum, on life history and population dynamics of two-spotted spider mites, Tetranychus urticae, feeding on aboveground tissue of strawberry plants, and examined associated plant growth and physiology parameters. Our experiments suggest that these three species of free-living rhizobacteria strengthen the constitutive, and/or induce the direct, anti-herbivore defense system of strawberry plants. All three bacterial species exerted adverse effects on life history and population dynamics of T. urticae and positive effects on flowering and physiology of whole strawberry plants. Spider mites, in each life stage and in total, needed longer time to develop on PGPR-treated plants and had lower immature survival rates than those fed on chemically fertilized and untreated plants. Reduced age-specific fecundity, longer developmental time and lower age-specific survival rates of mites feeding on rhizobacteria treated plants reduced their intrinsic rate of increase as compared to mites feeding on chemically fertilized and control plants. The mean abundance was lower in spider mite populations feeding on PGPR-treated strawberries than in those feeding on chemically fertilized and untreated plants. We argue that the three studied PGPR systemically strengthened and/or induced resistance in above-ground plant parts and enhanced the level of biochemical anti-herbivore defense. This was probably achieved by inducing or upregulating the production of secondary plant metabolites, such as phenolics, flavonoids and anthocyanins, which were previously shown to be involved in induced systemic resistance of strawberry plants. Overall, our study emphasizes that PGPR treatment can be a favorable strawberry plant cultivation measure because providing essential nutrients needed for proper plant growth and at the same time decreasing the life history performance and population growth of the notorious herbivorous pest T. urticae.

PESTICIDAL EFFECT OF SELECTED PLANT EXTRACTS ON Polyphagotarsonemus latus (BANKS) INFESTATION IN Corchorus olitorius L. JUTE

Many plant extracts could be considered as natural effective tool against yellow mite instead of synthetic chemicals. The research was aimed at studying the effects of plant extracts on Polyphagotarsonemus latus Banks infestation and jute yield production. This experiment was conducted in Manikganj, Bangladesh following randomized complete block design with three replications. Treatments were Neem oil 3% (T1), Neem leaf extract @ 1:30 (T2), Mahagoni seed extract @ 1: 10 (T3) Turmeric powder extract @ 1: 40 (T4), Garlic paste extract @ 1:30 (T5) and control (T6). Percent reduction of mite population was found in neem oil (87.94%), neem leaf extract (85.76%) and garlic paste extract (86.48%) at 72 hrs after spray. After 7 days of spraying, Neem oil treated plot received the best reduction (89.05 %) followed by neem leaf extract (87.03%), Mahogany (79.60%), turmeric (78.02%), and garlic (80.06%), respectively. Neem oil treated plot showed highest fibre yield (2.95tha-1). Control plot showed highest mite infestation with lowest yield contributing attributes. Neem oil/leaf extract and mahogany seed extracts were found effective to control yellow mite infestation resulting higher fibre yield production.

Acaricidal, ovicidal and fagoinhibition activities of seed extracts from Swietenia humilis against Tetranychus urticae under laboratory conditions

Two-spotted spider mite (Tetranychus urticae Koch) has been considered among the most important phytophagous pest both in field and greenhouse crops around tropical areas of the globe. Although synthetic pesticides have remained as the main method to control mite populations, alternatives strategies as biopesticides based on secondary metabolites derived from plants should be considered. Ascending polarity seed extracts of Swietenia humilis Zucc. (Meliaceae: Magnoliopsida) were evaluated for their egg and adult female toxicity, fagoinhibition as well as repellent activities against T. urticae under laboratory conditions. Ethyl acetate (EtOAc) medium polarity extract showed the highest ovicidal activity (92.54% at 1% concentration), adult female corrected mortality (EC50 = 0.0738%) as well as fagoinhibition (100% at 0.25% concentration). On the other hand, high polarity Methanol (MeOH) extract exhibits a predominant repellent profile (62% repellency) that was observed at 0.125% concentration with no significant toxicity. Our findings suggest different activity of extracts depending on their polarity. Otherwise, 13C NMR of a fraction from EtOAc extract led to detection of two major mexicanolide-type limonoids named humilinolides G and H. Finally, this study provides important bases for further research on the value of S. humilis seed extracts (ShSE) as an acaricide and the comprehensive use of the seeds for industrial multipurpose.

Role of Abiotic Factors on House Dust Mite Population: Control and Allergen Avoidance - A Review Article

House dust mites (HDM’s) are an important source of indoor allergens in the house dust and cause various kinds of allergies. They are strongly influenced by abiotic factors such as temperature, relative humidity and seasonal variations. HDM’s are present in houses all over the year but their number varies in different seasons and habitats. The moderate environmental temperature, high relative humidity and adequate food sources are the key factors for their proliferation. The season has a great effect on the mite population. In the rainy season, moderate temperature and high relative humidity are the favorable conditions for the growth of mites, and the population of mites reaches a peak level. Whereas, high temperature and low relative humidity during summer season significantly reduce the mite population level and in the winter season, fall in temperature will drastically reduce the mite number because mites perish due to chilling. Relative humidity of a particular place plays an important role in the growth of mites. By controlling the relative humidity of a particular place, the HDM allergens can be reduced in that place. The prevalence of these mites and their allergen content vary within the locations in the home. Mattresses, carpets, sofas are the main reservoir of HDM’s, as the dust and shed skin scales accumulate in these places and provide abundant nutrition to dust mites. To reduce the allergen content from houses, frequent cleaning and vacuuming of mattresses and pillows, the use of encasement should be advised for allergic subjects.

Assessing Repeated Oxalic Acid Vaporization in Honey Bee (Hymenoptera: Apidae) Colonies for Control of the Ectoparasitic Mite Varroa destructor.

The American beekeeping industry continually experiences colony mortality with annual losses as high as 43%. A leading cause of this is the exotic, ectoparasitic mite, Varroa destructor Anderson & Trueman (Mesostigmata: Varroidae). Integrated Pest Management (IPM) options are used to keep mite populations from reaching lethal levels, however, due to resistance and/or the lack of suitable treatment options, novel controls for reducing mites are warranted. Oxalic acid for controlling V. destructor has become a popular treatment regimen among commercial and backyard beekeepers. Applying vaporized oxalic acid inside a honey bee hive is a legal application method in the U.S., and results in the death of exposed mites. However, if mites are in the reproductive stage and therefore under the protective wax capping, oxalic acid is ineffective. One popular method of applying oxalic is vaporizing multiple times over several weeks to try and circumvent the problem of mites hiding in brood cells. By comparing against control colonies, we tested oxalic acid vaporization in colonies treated with seven applications separated by 5 d (35 d total). We tested in apiaries in Georgia and Alabama during 2019 and 2020, totaling 99 colonies. We found that adult honey bees Linnaeus (Hymenoptera: Apidae), and developing brood experienced no adverse impacts from the oxalic vaporization regime. However, we did not find evidence that frequent periodic application of oxalic during brood-rearing periods is capable of bringing V. destructor populations below treatment thresholds.

Bioefficacy of newer insecticides against sucking pests; jassid, whitefly and mite on Brinjal (Solanum melongena L.)

The present investigation was carried out at the Research Farm of Department of Agricultural Entomology, VNMKV, Parbhani during kharif 2018–19 to evaluate the efficacy of insecticides against sucking pests of brinjal. Seven insecticidal treatments cyantraniliprole OD, ffnpropathrin EC, flubendiamide SC, cartaphydrochloride SG, emamectin benzoate SG, λ-cyhalothrin EC and chlorantraniliprole SC were evaluated. Three sprays of each treatment at the interval of 15 days, starting with beginning of pest infestation, were given during the experiment. Cyantraniliprole 10.26% OD was found to be superior over the other insecticides. It recorded the lowest number of jassids and whiteflies, which was on par with the remaining treatments. Though the insecticides are not acaricides, but they showed a significant reduction in mite population over the untreated control plot. Fenpropathrin 30% EC was found effective against mites. This finding will be useful to identify the chemical combinations showing both insecticidal as well as acaricidal properties.

Crusted scabies in AIDS patient, a clinical challenge to be sorted out with a simple bedside test.

Norwegian or crusted scabies is a highly contagious severe variant of scabies described first among leprosy patients in Norway in 1848 by Boeck and Danielsen. Herein, we report a case of crusted scabies in an AIDS patient with large hyperpigmented macules covered with thick crusts present over the axilla, inguinal region, and gluteal region. Treatment started immediately with ivermectin, permethrin, and keratolytics after doing KOH microscopy. Mite population may exceed 1 million/person. Hence, it is highly infectious and can set off epidemics of scabies in home or institutions.

Efficacy of Miticides Applied at Tassel Stage for the Control of Spider Mites in Corn, 2020

Spider mite populations peaked during the week of August 19 and declined rapidly by August 26. Mite populations were made up entirely of two-spotted spider mites (Tetranychus urticae). The Portal with Exponent, Oberon, and Zeal treatments provided the best season-long control in this trial while Portal, Onager, and Mitomax II provided the most control 14 to 21 days after treatment. The lowest overall reduction in predatory mites during the season, when compared to control plots, occurred in the Portal and Onager treatments.

Seasonal mite population distribution on Caryocar brasiliense trees in the Cerrado domain.

Caryocar brasiliense Camb. (Malpighiales: Caryocaraceae) trees have a wide distribution in the Cerrado, and it is protected by federal laws. The need to monitor and understand pest damage to crops and forests is a major motivation for the study of population distribution. The mites (Acari) population distributions on C. brasiliense are unknown. We studied seasonal mite population distribution and their ecological indices on C. brasiliense trees in Cerrado areas during three years. Greatest number of Agistemus sp. (Stigmaeidae), Histiostoma sp. (Histiostomidae), Proctolaelaps sp. (Ascidae), and diversity and species richness on leaves of C. brasiliense occurred in the autumn; Tetranychus sp.1 (Tetranychidae) on leaves in the autumn and winter; Histiostoma sp., and Proctolaelaps sp. in fruits in the summer. No significant effect of season was observed in the abundance of Eutetranychus sp., Tetranychus sp.2 (Tetranychidae) and Acaridae. The populations of Acaridae, Eutetranychus sp., Proctolaelaps sp. and Tetranychus sp.1 negatively correlated with temperature. Proctolaelaps sp. and Tetranychus sp.1 correlated negatively with rainfall and Eutetranychus sp. and Proctolaelaps sp. positively with sunlight. The period with low rainfall and relative humidity increases the phytophagous mites and their predators, especially Agistemus sp.. The Tetranychus sp. and Histiostoma sp. species may become pests in C. brasiliense in the Cerrado domain.

ABUNDANCE, DAMAGE SEVERITY OF MAJOR INSECT PESTS OF CHILLI AND THEIR SUSTAINABLE MANAGEMENT THROUGH IPM BASED MODULES

Chilli (Capsicum annuum L.) is a vital and the most essential spice as well as vegetable crop in Bangladesh. Nowadays, the productivity of chilli is being decrease due to attack of insect pests. For the purpose of study on the abundance and damage severity, randomize 10 plants were selected from the experimental field. Besides, a field investigation was conducted at the field laboratory of Department of Entomology, Bangladesh Agricultural University (BAU), Mymensingh, Bangladesh in a randomized block design (RCBD) with a plot size of 1m2 with each treatment replicated three times in order to know the feasibility of four IPM based modules against major insect pests of chilli during Rabi season, 2020-2021 where Chilli variety BARI Morich-03 was used as an experimental crop. Results revealed that aphid exhibited the highest number of population (312.89/plant) and it caused damage maximum (36.57%) too which was followed by 264.36, 206.42, 186.95/plant and 32.16%, 23.45%, 19.88% in thrips, mites and jassid, respectively. The rank of incidence and damage was aphid>thrips>mites>jassid. On the contrary, for controlling the insect pests of chilli, of different IPM based modules, M-2 module was found the most promising in reducing the population of aphids (22.47/plant), thrips (53.18/plant), mites (62.45/plant), jassid (54.12/plant) and fruit borer (3.19/plant), where were obtained the greater plant height (72.35cm), highest number of branches (31.02/plant) & green fruits (404.13/plant) per plant, maximum weight of 1000 seed (4.03g) and better yield (8.42 t/ha). Furthermore, the highest benefit cost ratio (BCR) (1:1.56) was recorded by M-2 modules followed by M-4 (1:1.44), M-1 (1:1.12) and M-3 (1:1.09), respectively. Thus, the overall order of effectiveness of various IPM based modules was M-2>M-4>M-1>M-3. From the result, it also may be concluded that the cumulative insect pests per plant was strong as well as negatively correlated with the yield (t/ha) i.e. yield was increased due to decrease of cumulative insect pests per plant in chilli production. Therefore, M-2 can be used to reduction of major insect pests of chilli, environment safely and increased yield of chilli.

Influence of Abiotic Factors on the Population Dynamics of Scirtothrips dorsalis and Polyphagotarsonemus latus in Chilli

An experiment was conducted during 2018 and 2019 to find out the influence of abiotic factors (temperature, relative humidity and rainfall) on the population of two major insect pests in chilli crop; thrips, Scirtothrips dorsalis and mite, Polyphagotarsonemus latus. Results exhibited the peak activity of thrips during 21st to 25th SMW in 2018 and 40th to 42nd SMW in 2019. Highest population of mite was recorded during 44th to 45th SMW in 2018 and 38th to 39th SMWin 2019. Both thrips and mite populations exhibited negative correlation with rainfall (r = -0.349 and -0.357 in 2018; -0.571 and -0.292 in 2019). Thrips showed positive correlation with mean temperature (r = 0.622, 0.398), while negative with mean relative humidity (r = -0.5470, -0.5710) during both years. Chilli mite has showed opposite correlation to the thrips as negatively correlated with mean temperature (r = -0.804 and -0.4890) and positive with average humidity (r = 0.4920 and 0.3750) during 2018 and 2019.

Surveillance of synthetic acaricide efficacy against Varroa destructor in Ontario, Canada

Abstract The parasitic mite Varroa destructor (Mesostigmata: Varroidae) is the main culprit of honey bee (Hymenoptera: Apidae) colony mortality in Ontario, Canada. Most beekeepers use synthetic acaricides to control V. destructor infestations in their colonies, but the use of these products increases the risk of V. destructor developing resistance to the active ingredients, which is a growing concern. This study sought to determine the efficacy of three synthetic acaricides approved for use in Canada for control of V. destructor infestations, amitraz (Apivar™), tau-fluvalinate (Apistan®), and flumethrin (Bayvarol®), using the Pettis test. The mite mortality rate in populations of V. destructor differed for the acaricides tested. Amitraz caused a significantly higher mite mortality rate (92%) than flumethrin (78%) and tau-fluvalinate (72%) did. Amitraz was classified as “mostly effective” (90–97%), whereas flumethrin and tau-fluvalinate were classified as “minimally effective” (< 80%) for V. destructor control in the mite populations studied. Variation in mite mortality due to acaricide exposure was observed between apiaries and regions. The results highlight the importance of periodically assessing the varroacidal activity of acaricides to inform decisions to control the parasite when implementing integrated pest management strategies.

The temporal distribution of cyclamen mite, Phytonemus pallidus (Acari: Tarsonemidae), in strawberry and comparison of sampling methods

Abstract Cyclamen mite, Phytonemus pallidus (Banks) (Acari: Tarsonemidae), is a pest of strawberry, Fragaria × ananassa Duchesne (Rosaceae), that injures new growth, resulting in damage to leaves and fruit. The primary source of cyclamen mite in strawberry is infested planting material, and damaged plants tend to occur in small, isolated patches in perennial production systems. In the present study, we determined through repeated sampling of strawberry plants in Ontario and Saskatchewan, Canada whether relative cyclamen mite population levels were stable in commercial fields and whether overwintering and field renovation (mowing) affected populations. In Ontario, cyclamen mite counts were significantly correlated for 66% (10 of 15) of the paired comparisons from six sampling dates in more than one year, indicating a relatively stable distribution of cyclamen mite patches in strawberry fields. Winter caused high mortality (100 times fewer mites in spring than fall) and mowing caused some mortality (10 times fewer mites post- than pre-mow). We found that more cyclamen mite motiles were extracted from plant material stored in ethanol and triple-washed than were extracted using Berlese funnels, although counts from leaves were correlated between methods. No cyclamen mites were found in Saskatchewan. Knowing that cyclamen mite patches are local and spread is negligible will facilitate targeted applications of controls.

Resistance to amitraz in the parasitic honey bee mite Varroa destructor is associated with mutations in the β-adrenergic-like octopamine receptor

Varroa destructor is considered a major reason for high loss rate of Western honey bee (Apis mellifera) colonies. To prevent colony losses caused by V. destructor, it is necessary to actively manage the mite population. Beekeepers, particularly commercial beekeepers, have few alternative treatments other than synthetic acaricides to control the parasite, resulting in intensive treatment regimens that led to the evolution of resistance in mite populations. To investigate the mechanism of the resistance to amitraz detected in V. destructor mites from French and U.S. apiaries, we identified and characterized octopamine and tyramine receptors (the known targets of amitraz) in this species. The comparison of sequences obtained from mites collected from different apiaries with different treatment regimens, showed that the amino acid substitutions N87S or Y215H in the OctβR were associated with treatment failures reported in French or U.S. apiaries, respectively. Based on our findings, we have developed and tested two high throughput diagnostic assays based on TaqMan technology able to accurately detect mites carrying the mutations in this receptor. This valuable information may be of help for beekeepers when selecting the most suitable acaricide to manage V. destructor.

Predatory Capacity and Feeding Preference of Pesticide-Resistant Amblyseius deleoni Muma et Denmark (Mesostigmata: Phytoseiidae)

The population of the predatory mites Amblyseius deleoni had been decreasing due to continuous use of synthetic pesticides in tea plantations. Therefore, this study aimed to select pesticide-resistant individuals from a wild-type population of A. deleoni and to evaluate whether or not the resistant A. deleoni were still sensible as biological control agents. We exposed A. deleoni to (propargite), fungicide (copper oxide) and a neem seed extracts. We found that the propargite-resistant predatory mites consumed larvae and nymphs of Tetranychus urticae more than the control (wild type) (P < 0.05). There was no difference in the number of eggs and adults of T. urticae consumed (P > 0.05). The number of individuals of every stage of T. urticae consumed by copper-oxide resistant A. deleoni was the same (P > 0.05). In general, there were no changes in food preference in the resistant predators to the 3 of pesticides (P > 0.05). There were slight differences on the pattern of predatory capacity among the resistant predators to the three pesticides. Although the predators are resistant to the 3 pesticides, it took longer to consume their prey in comparison to the control. These findings suggested that pesticide-resistant A. deleoni were able to maintain their functions as a biocontrol agent.
 HIGHLIGHTS
 
 The effectiveness of Amblyseius deleoni as a natural predators have decreased due to continuous uses of synthetic pesticides to control pests and diseases on tea plantations
 Continuous exposure to propargite, CuO and neem seed extracts induced the predatory mites deleoni to develop resistance
 No significant changes in feeding preference and the predatory capacity of the mite deleoni on T. urticae after becoming resistant to pesticides
 Exposures deleoni to pesticides may have induced heritable epigenetic changes permanently or just reversible phenotypes without changing the DNA sequence

Biochemical Estimations of Tetranychus urticae Koch Infested Marigold Leaves in Summer and Winter Seasons under Screen House and Field Conditions

Background: African marigolds an important medicinal and ornamental plant is grown throughout the world. The two spotted red spider mite, Tetranychus urticae is one of the most destructive pests of the crop. Methods: Estimation of various minerals and stress measures of T. urticae infested and non infested leaves was performed in two seasons namely summer and winter under both screen house and field conditions. ANOVA was analysed under two factorial Completely Randomized Design. Mite population per leaf was correlated with each biochemical measures and statistical significance of data was analyzed. Result: Significantly lower nitrogen, phosphorous and potassium content was recorded in infested (2.01, 0.307, 1.509% dry weight) leaves as compared to uninfested leaves (2.93, 0.387, 1.874% dry weight) respectively. Summer season reported higher per cent loss in mineral content as compared to the winter season. The content of total phenol and proline was significantly more in infested leaves (18.75 mg/g, 57.07 µ/100 g) as compared to the uninfested leaves (11.42 mg/g and 47.50 µ/100 g). The per cent increase of phenol and proline ranged from (43.90 and 20.81%) in summer and (42.90 and 17.45%) in winter, respectively.