Biological parameters and host preference of Tyrophagus putrescentiae (Schrank) on different Pleurotus ostreatus cultivars

Tyrophagus putrescentiae (Acari: Acaridae) is a destructive pest of edible fungi. Different species of edible fungi have variable effects on the growth, development and fecundity of T. putrescentiae, but it is unclear whether these effects exist in the same species. We used nine cultivars of the oyster mushroom (Pleurotus ostreatus) to evaluate the development and reproduction parameters of T. putrescentiae at 26 ± 1°C and 80 ± 5% humidity. Different P. ostreatus cultivars had significant effects on the immature stages, female fertility, and reproductive lifespan. Total egg-to-adult development time ranged from 10.0 ± 1.2 d (on Po389 cultivar) to 12.5 ± 1.0 d (on Po62 cultivar). Mite mortality ranged from 54.3 ± 4.2% (on Po86 cultivar) to 100.0 ± 0.0% (on Po62 cultivar). The number of eggs laid per female ranged from 3.2 ± 0.4 (on Po45 cultivar) to 9.1 ± 1.1 (on Po86 cultivar). The average lifespan of females ranged from 3.0 ± 0.5 d (on Po45 cultivar) to 16.3 ± 1.7 d (on Po86 cultivar). Host preference of the mite was significantly different among the nine cultivars with a preference for cultivars Po65, Po80, Po389, and Po86. These results indicate that P. ostreatus cultivars significantly affect the biology of T. putrescentiae and the relationship between mite damage and mushroom yield.

Acaricidal efficacy of ultraviolet-C irradiation of Tetranychus urticae adults and eggs using a pulsed krypton fluoride excimer laser

Background Pulsed ultraviolet (UV)-C light sources, such as excimer lasers, are used in emerging non-thermal food-decontamination methods and also have high potential for use in a wide range of microbial decontamination applications. The acaricidal effect of an experimental UV-C irradiation device was assessed using female adults and eggs of a model organism, the two-spotted spider mite Tetranychus urticae. Methods UV-C light was generated by a pulsed krypton fluoride excimer laser operating at 248-nm emission wavelength. The pulse energy and pulse repetition rate were 5 mJ and up to 100 Hz, respectively. The distance from the light source to the target was 150 mm; the target surface area was 2.16 cm2. The exposure time for the mites and fresh eggs varied from 1 to 4 min at 5–300 mW, which corresponded to UV doses of 5–80 kJ/m2. Post-irradiation acaricidal effects (mite mortality) were assessed immediately and also measured at 24 h. The effects of UV-C irradiation on the hatchability of eggs were observed daily for up to 12 days post-irradiation. Results The mortality of mites at 5 and 40 kJ/m2 was 26% and 92%, respectively. Mite mortality reached 98% at 80 kJ/m2. The effect of exposure duration on mortality was minimal. The effect of irradiation on egg hatchability was even more significant than that on adult mite mortality, i.e. about 100% egg mortality at an accumulated dose of as little as 5 kJ/m2 for each exposure time. Conclusions A high rate of mite mortality and lethal egg damage were observed after less than 1 min of exposure to 5 mJ UV-C pulsed irradiation at 60 Hz. Pending further developments (such as beam steering, beam shaping and miniaturisation) and feasibility studies (such as testing with mites in real-life situations), the reported results and characteristics of the UV-C generator (modulation of energy output and adaptability to varying spot sizes) open up the use of this technology for a vast field of acaricidal applications that require long-range radiation. Graphical Abstract

The use of oxalic acid for the treatment bee colonies at varroatosis

Varroatosis is a contagious disease of the bee colonies caused by the Varroa destructor mite. The economic damage from the disease is compounded by the fact that the tick is a carrier of bacterial and viral infections of honey bees. In the absence of therapeutic measures, bee colonies die within two years. An analysis of modern means of combating varroatosis, used in domestic beekeeping, shows, that a significant part of them is represented by fluvalinate and amitrase-based drugs, which poses a threat to the pollution of beekeeping products with acaricide residues, and also contributes to the development of ectoparasite resistance to most veterinary drugs, created using the above chemical substances. In European apiaries organic acids (lactic, formic, oxalic, etc.), are increasingly used for treating bees with varroatosis. Oxalic acid is used in many industries, including medicine and pharmacology. In this regard, a study was made of the effectiveness of oxalic acid against varroatosis in the late autumn period on 15 bee colonies from apiary in the South of Tyumen Region. Broodless colonies were treated one time with a water-sugar solution (1:1) containing 3.2% of the drug by trickling bees into the bee spaces in the amount of 5 ml per bee space. It has been established, that as a result of treatment, the number of Varroa mites has decreased in experimental colonies on 87.1±2.2% (85.4-89.5%) . The maximum death of ectoparasites in experimental colonies was observed during the first two days after treatment. In the control group mite mortality during the observation period corresponded to 11.7±1.1%. For more objective data on the drug, further research is needed on the effectiveness of different concentrations of oxalic acid, their effect on the physiological state of bee colonies, bees overwintering and productivity.

Biological Control of the Raspberry Eriophyoid Mite Phyllocoptes gracilis Using Entomopathogenic Fungi

There is an urgent need to develop biological control methods against the eriophyoid mite, Phyllocoptes gracilis, which causes significant losses in organic raspberry production in Europe. The use of entomopathogenic fungi (EF) is a sustainable alternative to conventional chemical pesticides, reducing the risks of pesticide resistance and other negative environmental impacts of agriculture. The objective of this study was to assess the pathogenicity of three strains of EF, two of Beauveria bassiana and one of Metarhizium anisopliae, on P. gracilis under laboratory conditions. Fungal spore suspensions (1 × 107 spores per mL) were sprayed on detached leaves infested with P. gracilis. Treated mites were kept under controlled conditions (25 ± 3 °C, 72 ± 10% relative humidity and photoperiod of 16:8 (light/dark)) and mite mortality was assessed three, five and seven days after inoculation. At all three measurement points (days after inoculation), the mortality of P. gracilis was highest for B. bassiana strain BB 1.1 and M. anisopliae strain MA 10.1. Our data demonstrate that EFs are promising candidates for the development of biological control agents against P. gracilis in raspberry crops.

Biological effects of three bacterial species on Tetranychus urticae (Acari: Tetranychidae) infesting eggplant under laboratory and greenhouse conditions

This study evaluated the efficacy of three bacterial species. Acinetobacter sp. (concentration 2.237×108 cfu/ml), Bacillus subtilis (concentration 2.470×108 cfu/ml) and Bacillus qassimus (concentration 3.320×108 cfu/ml) were tested against the two-spotted spider mite, Tetranychus urticae, infesting eggplants under laboratory and greenhouse conditions. In addition, we studied their side effects on the predatory mite, Phytoseius plumifer. The highest efficiency rate on T. urticae was observed with Acinetobacter sp. sprays. Three days after treatment, mite mortality reached 87.15 and 77.29 % under laboratory and greenhouse conditions, respectively. Moreover, the mortality rates were significantly lower (72.22 and 67.11 % and 70.74 and 65.19 %) using B. subtilis and B. qassimus under lab and greenhouse conditions, seven days after treatment. The predatory mite, P. plumifer, showed higher tolerance than T. urticae to the three bacterial preparations. The results of this study indicated that Acinetobacter sp. has a strong efficacy on T. urticae and slightly affected the predatory species herein tested. This study introduces a potentially new strategy for biological control of phytophagous mites.

Syzygium aromaticum Essential Oil to the Control of Tenuipalpus heveae

The objective was to determine the effect of essential oils on the mortality and repellency of the Tenuipalpus heveae Baker mite (Acari, Tenuipalpidae). Leaf discs of rubber trees were deposited in Petri dishes containing a moistened cotton layer. Posteriorly, the essential oils were diluted to formulate solutions, which were sprayed onto the discs. The experimental design was completely randomized, in a 3 × 4 factorial design: neem, cedar and clove oils at doses 0, 10 μL, 50 μL and 100 μL, with five replicates, with ten adult females being considered per replicate. The exposure to the effect of essential oil was evaluated after 24, 48, 72 and 96 hours for the number of females dead and females in the cotton. The data were submitted to analysis of variance, the values were transformed into (x + 0.5)1/2, and the means were grouped by the Scott-Knot test at 5% probability for the treatments, the doses were submitted to regression analysis. From the 48 hours of evaluation, clove oil showed greater potential for adult mite mortality, being 1.38 in 48 hours, 1.40 in 72 hours and 1.50 in 96 hours. The dose of 100 μL presented a greater potential for the neem and clove oils. The clove essential oil has potential in the control of Tenuipalpus heveae.

Pathogenicity of Metarhizium anisopliae and Beauveria bassiana fungi to Tetranychus ludeni (Acari: Tetranychidae)

ABSTRACT The use of acaricides is the main control method for Tetranychus ludeni (Acari: Tetranychidae) in horticultural crops. This mite has been recorded causing damage to sweet potato (Ipomoea batatas L.). The use of pathogenic fungi is an alternative to chemical control. The objective was to evaluate the pathogenicity of the fungi Metarhizium anisopliae (Meetch) Sorok, and Beauveria bassiana (Bals.) Vuill. to phytophagous mite T. ludeni in sweet potato plants. Conidial suspensions of M. anisopliae and B. bassiana, at concentrations of 106 and 107 con.mL-1 were applied to sweet potato leaves. After 24 hours, five females of T. ludeni newly emerged were released on the leaves. The bioassay was arranged in a completely randomized design with factorial arrangement 2 × 2 (two species of fungi and two concentrations) plus the control (distilled water), with 10 repetitions per treatment. The evaluation consisted of observing of three biological parameters of the mite: mortality, oviposition, and repellency, after 24, 48, 72, and 96 hours of contact with the fungi. The isolates of M. anisopliae cause high mortality rates of T. ludeni in laboratory. Beauveria bassiana has the potential to suppress future generations of mite, reducing its oviposition rate. Repellency behavior was not observed.

The effect of the queen's age on the Varroa mite (Varroa destructor) burden of honey bee (Apis mellifera L.) colonies

An apiary trial was conducted in 2016 August to October in Szabolcs-Szatmár-Bereg County, Nyírmada to evaluate the influence of queen’s age on the Varroa destructor-burden in the treatment colonies. Sixty colonies of bees belonging to the subspecies Apis mellifera carnica pannonica in Hunor loading hives (with 10 frames in the brood chamber/deep super) were used. The colonies were treated with amitraz and the organophosphate pesticide coumaphos active ingredients. The amitraz treatment includes 6 weeks. The coumaphos treatment with Destructor 3.2% can be used for both diagnosis and treatment of Varroasis. For diagnosis, one treatment is sufficient. For control, two treatments at an interval of seven days are required. The colonies were grouped by the age of the queen: 20 colonies with one-year-old, 20 colonies with two-year-old and 20 colonies with three-year-old queen. The mite mortality of different groups was compared. The number of fallen mites was counted at the white bottom boards. The examination of spring growth of honey bee colonies has become necessary due to the judgement of efficiency of closing treatment. The data was recorded seven times between 16th March 2017 and 19th May 2017. Data on fallen mites were subjected to one-way analysis of variance (ANOVA) and Post-Hoc Tukey-test. Statistical analysis was performed using the software of IBM SPSS (version 21.). During the first two weeks after treatments, the number of fallen mites was significantly higher in the older queen’s colonies (Year 2014). The total mite mortality after amitraz treatment in the younger queen’s colonies was lower (P<0.05) compared to the three-year-old queen’s colonies. According to Takács and Oláh (2016) although the mitemortality tendency, after the coumaphos (closing) treatment in colonies which have Year 2014 queen showed the highest rate, considering the mite-burden the colonies belongs to the average infected category. The colonial maintenance ability of three-year-old queen cannot be judged based on the influencing effect on the mite-burden. The importance of the replacement of the queen was judged by the combined effect of several factors. During the spring-growth study (16th March–19th May) was experienced in the three-year-old queen’s colonies the number of brood frames significantly lower compared to the one- and two-year-old queen’s colonies. In the study of 17th April and 19th May each of the three queen-year-groups were varied. Therefore in the beekeeping season at different times were determined the colonial maintenance ability of queens by more factors: efficiency of closing treatment in early spring, the spring-growth of bee colonies, the time of population shift (in current study, this time was identical in each queen-year), honey production (from black locust).

Laboratory cage studies on the efficacy of some medicinal plant essential oils for controlling varroosis in Apis mellifera (Hym.: Apidae)

Varroosis is a disease of Apis mellifera L. caused by the mite Varroa destructor Anderson and Trueman. Essential oils and their chemical constituents offer a safe alternative to synthetic acaricides for the control of this mite in bee hives. The present study was conducted to evaluate anti-parasitic activity of essential oils from Thymus kotschyanus Bioss & Hohen., Mentha longifolia L., Eucalyptus camaldulensis Dehnh., and Ferula gummosa L. at concentrations of 1, 2.5, 4, and 5.5 µl/l air for 5 and 10 h. Findings indicated that mite mortality increased as oils concentration and exposure time increased. T. kotschyanus oil at 5.5 µl/l air caused a mite mortality rate of 54.4% and 84.43% after 5 and 10 h fumigation, respectively. At the same concentration and exposure time, the honey bee mortality was 0% and 7.2%, respectively. Application of M. longifolia and E. camaldulensis oils at 5.5 µl/l air resulted in 65.53% and 71.06% mortality in Varroa mites and 10.13% and 12% mortality in honey bees after 10 h exposure. Despite moderate acaricidal activity of F. gummosa oil against Varroa mite (49.69%), it was highly toxic to honey bee (30%). Also, GC/MS analysis of the oils showed that carvacrol (47.99%) and thymol (30.61%) in T. kotschyanus oil, piperitenone (36.86%), piperitenone oxide (27.53%),Cispiperitone epoxide (22.21%), and pulegone (8.38%) in M. longifoliaoil, 1,8-cineol (74.7%) and α-pinene (8.35%) in E. camaldulensis oil, and β-pinene (87.29%) in F. gummosa oil were the main chemical constituents. Collectively, our results led to a conclusion that T. kotschyanus, M. longifolia, and E. camaldulensis oils have enough potential to play an important role in integrated control programs of varroosis in apiaries.

Efficacy of essential oils against Varroa destructor infesting Apis mellifera Linn. colonies and their impact on brood development

Varroa destructor is a dangerous pest directly for beekeeping and indirectly for crops that require insect pollination. The present investigation has been carried out to study the efficacy and persistence of some essential oils and formic acid against Varroa mite in colonies of Apis mellifera Linn. at Pantnagar, Uttarakhand. The results revealed that highest mite mortality (77.54 %) with highest brood development (21.74 % increase) recorded in garlic oil followed by turmeric oil (75.84 %) with 15.39 per cent increases in brood development. The hives treated withT1(tulsi oil), T3 (turmeric oil), T4 (ajwin oil), T5 (cinnamon oil), T5 (clove oil) and T7 (formic acid) also showed good persistence with mite mortality ranging from 66.54 to 77.54 % and brood development -3.12 to 21.74 per cent increase after 3 weeks exposure of the treatments.