Spotted Spider Mite Research Articles

Toxicity and Repellent Activity of Plant Essential Oils and Their Blending Effects Against Two Spotted Spider Mites, Tetranychus urticae Koch

Miticidal and repellent activity of twenty plant essential oils against the adults of two spotted spider mites, Tetranychus urticae, were examined. Sandal wood oil was the most potent one in mortality, whereas clary sage oil exhibited the greatest repellent activity. On those twenty essential oils tested, no apparent correlation between toxicity and repellency was observed. When the most active oils were blended, the combinations tend to exhibit antagonistic interactions in both toxicity and repellent activity. The chemical compositions of sandal wood oil and clary sage oil were identified via GC/MS analyses, and the major constituents of sandal wood oils were sesquiterpene compounds, whereas the major ones for clary sage oil were monoterpenes. Among the major components in clary sage oil, linalyl acetate was not only the most abundant constituent, but also the most responsible one for its repellent activity.

Influence of companion planting on damson hop aphid Phorodon humuli, two spotted spider mite Tetranychus urticae, and their antagonists in low trellis hops

The effects on population development of damson-hop aphid Phorodon humuli and two-spotted spider mite Tetranychus urticae from planting drive rows with grass (2002-3 only), Brassica juncea, Phacelia tanacetifolia (2004-6 only), a meadow-mix of grass and flowering plants were compared with a bare soil control on aphid-susceptible low trellis hop (Humulus lupulus L.) cultivars First Gold (FGO) and Herald (HER) in 2002-4 and on partially aphid-resistant cultivar Boadicea (BOA) in 2004-6. Aphid and mite natural enemies were monitored from beat and foliage samples. Irrespective of ground cover treatment, generalist predators prevented damaging aphid populations from developing on BOA each year, and a combination of aphid–specific and generalists on FGO/HER in two of the three years experiments. Fewest migrant aphids settled, and lower aphid populations ensued, on FGO/HER with meadow-mix than other treatments, but the difference was insufficient to prevent peak populations of ca 1000 per leaf in 2004. Numbers of aphidiid parasitoids reflected aphid population densities on leaves with the highest numbers on FGO/HER in 2004, and none on BOA in any year. Seven species of primary parasitoids were recorded, dominated by Aphidius matricariae and A. picipes (95%), and eight species of hyperparasitoids which became increasingly prevalent as the season progressed. Spider mite population densities remained below ten actives per leaf in all but one year. They were regulated by a combination of phytoseiid mites (six species dominated by Typhlodromus pyri) and insect predators. Hops with meadow-mix had the highest population densities of spider mites, but also the highest numbers of phytoseiids. Although companion plants depressed average cone weight by ca 18% compared with the bare soil control, that loss may be preventable by using additional fertilizers, in which case permanent meadow-mix would provide a suitable companion plant treatment for biological control of both P. humuli and T. urticae on aphid-resistant low trellis cultivars such as BOA, but used alone is unreliable on aphid-susceptible cultivars.

Heterotic Performance and Gene Action for Yield, Yield Components and Resistance to the Two –Spotted Spider Mite in Cucumber

Nine accessions of cucumber and Beta alpha cultivars from North Central Regional Plant Introduction Station (USDA) viz, PI 109483 (25), PI 169352 (24), PI 169395 (23), PI 211117 (32), PI211984 (26) , PI 169392 (20) ,Beta-alpha (B), PI 178885 (2), PI 218036 (3) and PI 390238 (4) as well as their twenty one F1 hybrids in a line × tester meeting design were used in the present study to estimate heterosis percentage (relative to both mid and better parents), potence ratio and combining ability (general and specific) data were recorded for some characters in cucumber (Cucumis sativus L.) beside estimating resistance to the two – spotted spider mite, Tetranychus urticae Koch. The experiment was conducted at Kaha Research Farm, Kaliobia Governorate under unheated plastic house in three successive seasons, 2015, 2016 and 2017. The obtained results reflected that significant differences were observed between all the studied characters. In some crosses, high rate of parent heterosis and potence ratio values were observed for the traits supporting the over dominance hypothesis. Other degrees of dominance were observed in many crosses concerning some traits. These results revealed that the hybrid vigor is important for commercial production of cucumber hybrid. Estimates of GCA effects showed that the parent PI 109483 (P25) as well as a line showed that it's the best parent for early and total yield while, PI 169352 (24) was the best parent for early, total yield, average fruit weight and fruit length and PI 169392 (20) was the best parent for earliness characters. But PI211984 (26) and Beat alpha were the best parents for reducing number of movable stages of T. urticae. Estimates of SCA effects cleared that the F1 cross (P23×P2) was the best combination for early, total yield and the period to first female flower anthesis. Also, the F1 cross (B ×P3) was the best combination for total yield, early yield, main stem length and the average fruit of weight. The F1 cross (P26×P4) was the best cross for total yield, early yield and number of node carried first female flower. The F1 cross (P32×P2) was the best cross for reducing number of movable stages of T. urticae, as well as, decreasing the level infestation of the two spider mites on cucumber plants.

Effect of Some Soybean Varieties on Biological Aspects and Fecundity of The Two Spotted Spider Mite , Tetranychus urticae Koch ( Acari: Tetranychidae)

Biological and fecundity of the two spotted spider mite, Tetranychus urticae Koch reared on three soybean varieties: Giza 111, Giza 83 and Giza 22 were evaluated under laboratory conditions of 25±1 oC and 65± 5% R. H. The developmental times from egg to adult stage ranged from 14.15 to 11.4 days on Giza111 and Giza83 varieties, while, on Giza22 variety it lasted 10.10 days for female, while, the male life cycle stayed 12.3, 10.2 and 9.3 days, when, fed on the same soybean varieties. Female longevity was differed among the tested soybean varieties whereas, it lasted 10.90, 9.15 and 9.45 days when fed on, Giza111, Giza83, and Giza22 varieties of soybean , respectively. The tested soybean varieties greatly affected fecundity, female deposited of the reared mite , where the maximum number of laid eggs were registered on Giza22 variety ( 45.50 egg), while, the least number of laid eggs of the spider mite, T. urticae was observed on Giza111 variety( 34.50).

Selection of processing tomato genotypes resistant to two spotted spider mite

ABSTRACT One of the major problems in cultivation of tomato is the occurrence of pests and diseases. The objective of the research was to select genotypes from the second generation of the first backcross (F2BC1) between the tomato cultivar for processing S. lycopersicum (cv. Redenção) and the wild access S. habrochaites var. hirsutum (PI-127826), with high levels of zingiberene (ZGB), resistant to the twospotted spider mite Tetranychus urticae (Acari: Tetranychidae). From the F2BC1 population. The ZGB content was quantified and five plants with high zingiberene selected (RVTZ 2011-079-117, RVTZ 2011-079-185, RVTZ 2011-079-335, RVTZ 2011-079-345 and RVTZ 2011-079-503) and four with low zingiberene content (RVTZ 2011-079-417, RVTZ 2011-331-460, RVTZ 2011-079-538 and RVTZ 2011-079-548) were selected. Genotypes selected for high and low ZGB content and the parentals S. habrochaites var. hirsutum access PI-127826 and ‘Redenção’ were evaluated for repellency to the twospotted spider mite. There was a significant and inverse correlation between ZGB content and average distances travelled by mites on tomato leaflets. The genotypes of the F2BC1 generation with high zingiberene levels RVTZ 2011-079-117, RVTZ 2011-079-185, RVTZ 2011-079-335, RVTZ 2011-079-345 and RVTZ 2011-079-503 are promising for progress in achieving resistant lines to arthropod pests. Among them RVTZ 2011-079-117 stands out for resistance to twospotted spider mite.

Management of an emerging pest, Tetranychus urticae Koch (Acari: Tetranychidae), with pesticides in eastern Ethiopia

Outbreak of two-spotted spider mite, Tetranychus urticae Koch, happened on potato ( Solanum tuberosum L.) in eastern Ethiopia in 2014 and effective pesticides as part of IPM practice were sought from greenhouse and laboratory experiments at Haramaya University, Ethiopia. The objective of the study was to identify pesticides with the highest efficacy against the mite. Potatoes infested with mites were used in the efficacy trial. Treatments, 9 pesticides and a control, were applied 2 times at weekly intervals. Mites per leaf before and after each spray were counted. Promising pesticides were further screened with leaf-disc spray, and dip methods. Adult mortality was recorded after 24 and 48 hours. Chlorantrniliprole + Lambda-cyhalothrin, Amitraz, Profenofos, Profenofos “Q” 720 g l-1, and Paraffin oil showed superior efficacy on eggs and mobile stages; though Paraffin’s efficacy became clear 14 days later. Paraffin had the lowest mortality in leaf-disc sprays, but better mortality in the leaf-disc dip. This was attributed to complete wetting by the latter. Chlorantrniliprole + lambda-cyhalothrin, Profenofos, Profenofos “Q” and Paraffin were identified as promising pesticides for the two spotted spider mite management on potato. Key Words: Pesticides, potato, two spotted spider mite

CONFIRMATION OF PRESENCE OF A PREDATORY GALL MIDGE, Feltiella acarisuga, (Vallot, 1827) AND STAPHYLINID PREDATOR Oligota oviformis Casey, 1893 OF A TWO SPOTTED SPIDER MITE (Tetranychus urticae, Koch, 1836) IN SLOVENIA

The two spotted spider mite, Tetranychus urticae C. L. Koch, 1836 is one of the most important pests of greenhouse crops worldwide. Due to its polyphagic range of hosts and rapid development it forms great populations and as such represents a suitable host/prey for lots of natural enemies usable in biological control. Most commonly used predators of Tetranychid mites are predatory mites (Phytoseiulus persimilis Athias-Henriot, 1957, Amblyseius swirskii Athias-Henriot, 1962 ,…), but among most voracious predators is the larva of a predatory gall midge, Feltiella acarisuga (Vallot, 1827) that was found also in greenhouses of the Biotechnical Faculty in Ljubljana on eggplant leaves in 2017. Besides the predatory gall midge also another predator, staphylinid Oligota oviformis Casey, 1893 beetles and larvae were found in great numbers. After positive identification of F. acarisuga found naturally in Slovenia, it can be added to the list of indigenous species of natural enemies and thus can be used in biological control programs in greenhouse crop protection against spider mites.

Effect of host plants on the biology of predatory mite, Neoseiulus longispinosus (Evans) cultured on two spotted spider mite, Tetranychus urticae Koch

Study on the effect of selected host plants viz., brinjal, bhendi, french bean and butter bean on the biology of predatory mite, Neoseiulus longispinosus (Evans) revealed that there was faster development of the predatory mite on bhendi (4.33 ± 0.52 days) as compared to other host plants. Total development period was 4.68 ± 0.90, 4.71 ± 0.78 and 5.02 ± 0.70 days on french bean, butter bean and brinjal respectively. There were no significant differences in adult longevity and fecundity of N. longispinosus when it cultured on bhendi and butter bean. Further, study on influence of leaf morphological characters indicated the negative effect of trichome density, trichome length and leaf thickness on the development of N. longispinosus.

Integrated management of two spotted spider mite Tetranychus urticae koch on jasmine and rose

The field experiments were conducted to evolve a IPM strategy against two spotted spider mite Tetranychus urticae Koch on jasmine and rose crops. The study revealed that tulsi (Ocimum sanctum L.) leaf extract @10% or neem (Azadirachta indicia A. Juss.,) oil @ 3% or nochi (Vitex negundo L.) leaf extract @ 5% followed by Beauveria bassiana @ 1x 108 CFU/g or Lecanicillium lecanii @ 1x 108 CFU/g followed by bifenazate 240 SC @ 0.75 ml/l or spiromesifen 240 SC @ 0.75 ml/l as foliar application at fortnightly interval proved effective.

Evaluation of mycoacaricides against two spotted spider mite, Tetranychus urticae Koch on jasmine (Jasminum sambac Ait.)

An investigation was carried out in field conditions at two different locations i.e., Vadipatti and Allanganallur blocks of Madurai district of Tamil Nadu to evaluate the bio-efficacy of certain commercially available mycoacaricides against two spotted spider mites Tetranychus urticae Koch on Jasmine (Jasminum sambac Ait.). From the cumulative mean data of this study it was found that among the mycoacaricides evaluated, Beauveria bassiana (Bals-Criv.) Vuill. @ 1 × 108 CFU/g and Lecanicillium lecanii (Zimm.) Zare & W. Gams @ 1 × 108 CFU/g recorded the highest per cent reduction of eggs (59.99 and 58.61% at Vadipatti block and 57.20 and 55.78% at Alanganallur block) and mites (63.39 and 61.98% at Vadipatti block and 59.44 and 58.51% at Alanganallur block) respectively, which were statistically on par in their bio-efficacy against T. urticae on J. sambac. Regarding the flower yield; amongst the test mycoacaricides, the highest per cent increase in flower yield was recorded in case of B. bassiana @ 1 × 108 CFU/g (56.20% at Vadipatti block and 55.33% at Allanganallur block) and L. lecanii @ 1 × 108 CFU/g (54.89% at Vadipatti block and 55.01% at Allanganallur block) along with the highest cost benefit ratio of 1: 1.83 and 1: 1.59 at Vadipatti block and Allanganallur block respectively and 1: 1.61 and 1: 1.50 at Vadipatti block and Allanganallur block respectively, which were statistically at par. Thus, B. bassiana @ 1 × 108 CFU/g and/or L. lecanii @ 1 × 108 CFU/g can be recommended for the management of T. urticae infesting Jasmine as a substitute to synthetic chemical acaricides due to their host specificity, safety to natural enemies with no toxic residues.

Field efficacy of new insecticide molecules against sucking pests of Eggplant, Solanum melongena L.

A field trial was conducted in farmers holding at Alanganallur block of Madurai using the popular brinjal cv. Mdu-1 to evaluate the efficacy of certain new insecticide molecules against sucking pests viz., aphids, brown plant hopper, thrips, whitefly and two spotted spider mites of eggplant. The overall impact of three rounds of foliar spray revealed that Abamectin 1.8 EC @ 0.5 ml/l caused maximum reduction of sucking pest population followed by Thiamethoxam 25 WG @ 0.75 g/l, apart from this Spinosad 45 SC @ 0.2 ml/l had moderate efficacy against sucking pests followed by Diafenthiuron 50 WP @ 1 ml/l, Fenazaquin 10 EC @ 0.75 ml/l, Fenpyroximate 5 EC @ 0.8 ml/l, followed by Bifenazate 240 SC @ 0.75 ml/l.

Genetic diversity within and among two-spotted spider mite resistant and susceptible common bean genotypes

Two-spotted spider mite (Tetranychus urticae C. L. Koch, 1836), is one of the most destructive herbivores of common bean. Very little is known about the diversity among resistant sources in this crop. The present study was conducted to characterize 22 resistant and susceptible common bean genotypes by 8 Simple Sequence Repeats (SSRs) and 8 Random Amplified Polymorphic DNA (RAPD) markers. These SSR and RAPD primers produced 100 % and 81.8 % polymorphic bands. Based on RAPD fingerprints and SSR profiles, pairwise genetic similarity ranged from 0.0 to 0.857 and from 0.125 to 1, respectively. The resistant and susceptible common bean accessions were grouped together in the dendrograms generated from RAPD and SSR clustering analyses. The results indicate that RAPD and SSR analysis could be successfully used for the estimation of genetic diversity among genotypes. SSR markers could group genotypes according to their resistibility and susceptibility to the spotted spider mite but RAPD could not. Therefore, the SSR markers can facilitate the development of resistant common bean cultivars through breeding programs against T. urticae.

MORINGA PLANT, Moringa oleifera LAM., AS A SOURCE OF BIOPESTICIDE

Fifty grams of Moringa seeds were ground and then sieved. The solvent methylene chloride was added to the fine powder. The obtained solution was submitted to column chromatography analyzed. Each output was separated and identified by Fourier Transform Infrared spectroscopy (FTIR), 13Carbonand Nuclear magnetic resonance spectroscopy. The obtained substances were tested against each of the adult females of the two spotted spider mite Tetrancus urticae (Koch) and the cotton mealybug Phenacoccus solenopsis Tinsley. The efficiency effects of the obtained compounds were evaluated after 24 hours after application. No effect for all the tested compounds was recorded except for Rhamnosyloxy-benzyl isothiocyanate. The results showed that the values of LC25, LC50 and LC90 were 150, 388 and 2370 ppm, respectively after application for the two spotted spider mite T. urticae, whereas LC25, LC50 and LC90 were found to be 251.14, 839.89 and 8326.2 ppm after 24 hours of application, respectively on the cotton mealybug P. solenopsis.

The Effect of Magnetic Force and Magnetic Water on Behavior and Population of Tetranychus urticae and Amblyseius gossipi on Soybean in the Laboratory and Field.

Two experiments were carried out to study the effects of magnetic force and magnetic water on two spotted spider mites Tetranychus urticae (Koch) (Acari: Tetranychidae) andits predator Amblyseius gossipi(El-Badry)(Acari: Phytoseiidae) .In The first experiment leaflets of infested soybean with T.urticae and A. gossipi were passed through different concentrations of magnetic force and magnetic water at different time intervals the concentrations of magnetic force and magnetic water in the laboratory were 100,200,300,400 and 500 Gausses, respectively, while Magnetic force and magnetic water in the field were 1000,2000,3000,4000 and 5000 Gausses, respectively. The second experiment was conducted by sprayed the infested leaflets with T. urticae and A. gossipi at three time intervals. The results in both experiments revealed that the numbers of two tested mite and its predator were reduced after treated with magnetic force or magnetic water. Also, the data indicated that magnetic force was the most effect on adults and the eggs stage of T. urticae, but was the lowest toxic effect on A. gossipi ,while magnetic water was moderate effect on eggs and adults of two tested mite and its predator. Under the field condition the magnetic force was the most effect on behavior and population of T. urticae and A. gossipi, while magnetic water was moderate effect on the population and behavior of eggs and moile stages to T. urticae and adults of A. gossipi

Effects of abamectin on two spotted spider mite and Trichogramma brassicae and efficacy of its residual effects applied on the bean plants

For evaluating lethal effects of abamectin on T. urticae leaf dipping method was used. Then T. brassicae adults were treated with LC10 and LC50 values obtained from probit analysis of the mite bioassay results using toxicity bioassay with fresh residue method. For evaluating residual effects of abamectin, bean plants were sprayed with twentieth of recommended field dose of abamectin (equal to 25 ppm of trade product). Leaf pieces were prepared from treated plants in different time intervals and the adult mites were transferred on them. Mortality was recorded after 24 h. Probit analysis of lethal experiment against T. urticae revealed 0.05, 0.417 and 3.26 ppm from trade product as LC10, LC50 and LC90 values, respectively. Results of residual effects experiment showed that mite mortality was 100% in 1 day after plant spraying which decreased to 55.62% in 21 days after spraying. LC10 and LC50 values of abamectin tended to 53.87 and 72.57% mortality of T. brassicae, respectively.

The Effect of Magnetic Force and Magnetic Water on Behavior and Population of Tetranychus urticae and Esuseis scutalis on Soybean in the Laboratory and Field.

Two experiments were carried out to study the effects of magnetic force and magnetic water on two spotted spider mites Tetranychus urticae (Koch) (Acari: Tetranychidae) and Esuseis scutalis (El-Badry) (Acari: Phytoseiidae) .In the first experiment leaflets of infested soybean with T. urticae and E. scutalis were passed through different concentrations of magnetic force and magnetic water at different time intervals the concen-trations of magnetic force and magnetic water in the laboratorywere 100, 200, 300, 400 and 500 Gausses, respectively, while Magnetic force and magnetic waterin the field were1000, 2000, 3000, 4000 and 5000 Gausses, respectively. The second experiment was conducted by sprayed the infested leaflets to T. urticae and E. scutalis at three time intervals. The results in both experiments revealed thatthe numbers of two tested mites were reduced after treated with magnetic force or magnetic water. Also, the data indicated that magnetic force wasthe most effect on adults and the eggs stage of T. urticae, but was the least effective on E. scutalis, while magnetic water was moderate effect on eggs and adults of two tested mites. Under the field condition the magnetic force was the most effect on behavior and population of T. urticae andE. scutalis, while magnetic water was moderate effect on the population and behavior of eggs and motile stages to T. urticae and adults of E. scutalis

Bioactivity of Indigenous Medicinal Plants against the Two-Spotted Spider Mite, Tetranychus urticae

Forty two methanol extracts and 12 aqueous extracts of 29 indigenous medicinal plant species were tested for their acaricidal bioactivity against the two spotted spider mite, Tetranychus urticae adults at the laboratory. Fourteen methanol plant extracts caused significant mortality in mites. This is the first report for the potential effect on survival of mites for 27 tested endemic plant species. Methanol whole plant extracts (WPEs) of Lotus carmeli, Alchemilla diademata, Eryngium deserlorum and aqueous fruit extracts (FrEs) of Melia azedarach caused toxic effects against the adult mites in the range of 41-46% mortality. The methanol WPE of L. carmeli and the aqueous FrE of M. azedarach (1:5) caused the highest mite mortality of 43.55% and 45.55%, respectively and each was used as reference sample for potential acaricidal activity in the methanol and aqueous treatment groups. The latter extract was not significantly different in its effect from aqueous extracts of M. azedarach leaf extract (LE) and Achillea damascena WPE. Methanol extracts of Salvia rubifolia flowers and Calendula palestina FrE were found to be more active against the adult mite than their extracts of other plant parts as leaves and flowers, respectively. The former two extracts, flower extracts of Anthemis scariosa, Echinops gaillardoti, Nepeta curviflora, and Ranunculus cuneatus, leaves and stems extract of An. scariosa and WPEs of Melissa inodora, Ranunuculus myosuroides, Origanum libanoticum and Ac. damascena were found to be comparable in their acaricidal activity to that of the whole plant extract of L. carmeli. Thus, these bioactive extracts of some local plant species can cause toxicity to adult T. urticae mites and consequently could be an alternative control for mite pests.

First record of Polyphagotarsonemus latus (Banks 1904) (Αcari: Tarsonemidae) on greenhouse peppers in Crete

The broad mite, Polyphagotarsonemus latus Banks (Acari: Tarsonemidae), was first noticed on greenhouse pepper cv Cleopatra and Sonar in Ierapetra (Southeastern Crete) in 1984. During 1984 there were scattered mite infestations in a few greenhouses but in the following years it has become an increasingly important pest of peppers. The mite has been also found on cucumber cv Cnossos, aubergine cv Flaska and Solanum aviculare (indigenous of Amazonios) in the greenhouses of the Ierapetra Experimental Station. It atta­cks the growing points, young foliage, stem flowers and fruits. The growing points and bud are distorted, the young leaf margins down curl, the apical leaves crinkle, the leaf veins fuse and distort and the color changes to dark green, the fruits and stem crack and turn russet, mis-shape resembling like a fruit or stem scab and finally the small leaves and flowers fall off. Severely affected plants have little or no young growth, remain stunt and all fruitlets are aborted. The general look of the infested plants is similar to those affected by hormone weedkiller. Affected plants could not recover easily and the symptoms persisted for many weeks in spite of the acaricide treatments applied by the growers. In an artificial infestation of young pepper plants cv Sonar by 100-200 individuals, the symptoms of broad mite damage appeared in eight to ten days under growth chamber conditions (24±0.5°C, 60±5% R.H., 12.000 Lux for 16 hours daily).In Greece, the broad mite was first recorded on cotton leaves in 1969 and later on citrus trees. In Britain, it causes serious problems since 1978. It has been also noticed in several other countries of Europe. The spread of P. latus in many greenhouse plants in Britain was caused by the absence of acaricide treatments in green­houses where biological control against the two spotted spider mite Tetranychus urticae was ap­plied and the predator Phytoseilus persimilis was introduced by French bean leaves which was a recorded host of broad mite. The female longevity varies between 7-18 days depending mainly on temperature. The mean number of eggs/female is 40-50. The life cycle of broad mite is completed in 441, 205 and 98 hours at 14, 24 and 30°C, respectively. The developmental rate of various stages of the mite increased with the temperature but declined at about 35°C. The broad mite has been recorded on a wide range of hosts: tea plant, beans, tomatoes, cucumber, pep­pers, aubergines, citrus, zerbera, fuchsia, jasmin­um, magnolia, cotton, jute, coffee, avocado etc.

Evaluation of entomopathogenic fungi for the control of Tetranychus urticae (Acari: Tetranychidae) and the effect of Metarhizium brunneum on the predatory mites (Acari: Phytoseiidae)

The efficacy of the entomopathogenic fungi (EPF), Metarhizium brunneum (strains ARSEF 4556 and V275), Metarhizium flavoviride UPH-0288, Lecanicillium lecanii UPH-0241, and Beauveria bassiana UPH-1103 against the different developmental stages of the two spotted spider mite (TSSM), Tetranychus urticae, was investigated at 1×107conidia/ml concentration in detached leaf Petri dish and whole plant pot assays. One of the most virulent strains, M. brunneum V275 (=Novozymes Met52/F52), was screened using a range of doses against adult female predatory mites, Phytoseiulus persimilis and Neoseiulus californicus. All the EPF tested killed 11.8–14.3% and 12.8–17% of the TSSM eggs in Petri dish and pot assays, respectively. They also caused 57.3–90.3% and 29.5–67.5%, mortality of the mobile stages in the Petri dish and pots trials, respectively. TSSM adults were generally more susceptible to the EPF than the juveniles. Adult mortality was >80% for all strains except M. flavoviride which caused 67% mortality. Predatory female mites were also susceptible to M. brunneum V275 with mortality being dependent on the dose and predator species; thus mortality at 1×106, 1×107 and 1×108conidia/ml was 57.5, 80.5, and 99.5% for P. persimilis and 51.5, 75.0, and 90.5% for N. californicus, respectively. However, subsequent biological stages (eggs and juveniles) were not affected by the fungal pathogen, and the number of new generation mobile stages increased 3–9-fold compared with the initial number of released predatory mites. The current study thus shows that M. brunneum V275 application with the releases of predatory mites have the potential to suppress T. urticae.

Influence of weather factors on insect and mite pests infesting French bean (Phaseolus vulgaris L.), Assam, India

A field experiment was carried out in the Integrated Crop Research (ICR) farm, Assam Agricultural University, Jorhat to determine the impact of weather parameters on insect and mite pests infesting French bean (Phaseolus vulgaris L.) during 2013-14 and 2014-15. The weather parameters had a significant impact on population build up of various French bean crop pests. Cutworm population found to be positive and significant correlation with morning relative humidity (r=0.573) during 2014-15 while aphid showed a positive significant correlation with maximum temperature (r=0.555) and BSSH (r=0.671) but negative with relative humidity (r=-0.562*) in 2013-14. Two spotted spider mite (TSSM) population showed a positive significant correlation with morning relative humidity (r = 0.661* and r=0.617*) in both the years and negative correlation with maximum temperature (r=0.603 and r=559) in 2013-14 and 2014-15, respectively. A negative significant correlation with maximum temperature (r=706) and positive correlation with relative humidity (r=568) with pod borer population during 2013-14. The rain fall (r=589) had a negative significant correlation with Thrips population during 2013-14. Whitefly population found to be negative significant correlation with maximum temperature (r=554 and r=553) and positive correlation with morning relative humidity (r=605 and r=674) in 2013-14 and 2014-15, respectively. This present findings will certainly be a helpful tool for profitable cultivation of French bean crop by forecasting insect and mite pests arrival as well as management point of view.