Control Of Mites Research Articles

Natural enemies of Varroa destructor identified from Eastern North American honey bee colonies: a biological survey of candidates for mite control from Maryland, USA

ABSTRACT A survey was conducted of microbes and arthropods associated with Varroa destructor (Acari: Varroidae) mites (hereafter, Varroa) collected from honey bee colonies in Maryland, USA. Live Varroa were challenged with samples of both microbes and arthropods and assessed for their potential as biocontrol agents against the mites. To our knowledge, this is the first survey of natural enemies of Varroa conducted in North American honey bee colonies. The survey revealed 21 fungi, 25 bacteria, one nematode, and 8 arthropod species associated with Varroa in honey bee colonies, and from challenge assays using 11 of these, including 4 species of fungi, 2 species of bacteria, a parasitic nematode, 2 insects (Hemiptera and Hymenoptera), and 2 arachnids (Pseudoscorpiones) were capable of killing Varroa. This assemblage of Varroa natural enemies was similar to taxa identified from surveys conducted elsewhere globally, suggesting there is a core assemblage of organisms capable of killing Varroa that are best suited to tolerate the sometimes-hostile abiotic and biotic conditions of the hive environment. Generally, entomopathogenic fungi and bacteria assessed in our study showed the highest efficacy against Varroa, and for some, efficacy was comparable to that determined by other researchers, suggesting entomopathogenic fungi and bacteria appear to be the most promising candidates for development into commercially viable varroicides. A novel parasitic nematode identified from our survey killed greater than 90% of infected hosts. In addition, the behaviours of some arthropods toward Varroa observed in our study were indicative of predation on the mites.

An amitraz-based miticide does not appear to affect the bacterial microbiota of Apis mellifera (Apidae: Hymenoptera, Linnaeus, 1758) or Varroa destructor (Acari: Varroidae, Anderson & Trueman, 2000)

ABSTRACT The use of pesticides in beehives constitutes an important health issue for honey bees (Apis mellifera). Miticide treatments are not lethal to bees but could still impose significant sublethal costs. This study examined the impacts of amitraz, a commonly used miticide, on the bacterial communities of the honey bee gut and Varroa destructor mites. We sequenced and compared gut 16S rDNA composition pre – and post-amitraz treatment. Amitraz did not significantly influence bacterial gut communities in either honey bees or mites during the first six weeks following treatment. The gut bacterial community of bees was mainly dominated by the commonly observed microbiota in bees, which included species in the genera Gilliamella, Snodgrassella, and Frischella. Deformed wing virus (DWV) loads were analysed but were also unaffected by amitraz treatment over the six-week period studied. The bacterial community of Varroa destructor mites was heavily dominated by Bartonella spp., in contrast to results observed elsewhere. Our results indicating that amitraz does not appear to affect honey bee microbiota should be helpful for beekeepers who rely on this pesticide for mite control.

Steam Treatment Controls Cyclamen Mite (Phytonemus pallidus) Without Compromising Strawberry Plant Survival, Growth and Yield

ABSTRACT Cyclamen mite is a pest of strawberry that is difficult to control due to its small size and preference for inhabiting concealed spaces in new plant growth. Steam treatment of transplants effectively reduces some strawberry pathogens and may be a valuable tool against cyclamen mite. Strawberry transplants (“Jewel” and “Annapolis”) that were artificially infested with cyclamen mite were steam-treated at 44°C for 1 h or at 48°C for 0.5 h. Both treatments reduced cyclamen mite numbers by > 99% compared to the control, and 44°C for 1 h had no negative effects on plant survival, growth or yield. In a second, similar, field experiment, transplants (“Jewel”) were categorized by crown size as small (6–8 mm) and large (10–13 mm) and steam-treated at 44°C for 1 or 4 h. Steam treatments reduced cyclamen mite numbers by 92–93% compared to the control, but in the 4 h treatment, survival of small crowns was 40%. Steam treatment of strawberry transplants at 44°C for 1 h is an effective tool and may reduce reliance on miticides for cyclamen mite control. Additional research is needed to determine the optimal steam treatment protocols for cyclamen mite control and to understand the effect of the steam treatment on strawberry transplants with different crown sizes.

Enhanced mite control and agricultural safety with etoxazole-loaded chitin nanocrystals: Synthesis, characterization, and ecological impacts

Chitin nanocrystals (ChNCs), known for their high aspect ratio, surface charge, and mobility, are promising bio-based nanomaterials for drug delivery. However, their potential as pesticide carriers in agriculture remains underexplored. Etoxazole, a diphenyl oxalate acaricide, effectively inhibits egg hatching and the normal molting process in mites but suffers from rapid degradation and short persistence in field applications. This study introduces a novel formulation, Eto@ChNC, prepared by complexing TEMPO-oxidized ChNCs with etoxazole via a one-pot method. Eto@ChNC was evaluated for controlling Tetranychus urticae, demonstrating significantly enhanced rapid action and prolonged efficacy compared to traditional formulations. The formulation increased the synergistic effects on mite eggs and deutonymphs by 41.74 % and 67.85 %, respectively, extending effectiveness by two days. The improved performance was attributed to the enhanced wetting ability of Eto@ChNC on leaf surfaces and its superior inhibition of the epidermal chitin content in T. urticae, facilitating greater etoxazole penetration. Transcriptome sequencing revealed numerous differentially expressed genes related to chitin metabolism, elucidating the molecular mechanisms underlying the increased efficacy. Safety assessments confirmed that Eto@ChNC did not elevate toxicity to earthworms or predatory mites and promoted the growth of wheat and cowpea, underscoring its environmental safety. These findings highlight Eto@ChNC as a significant advancement in bio-based acaricide formulations, offering promising applications in mite management.

RNAi of nuclear receptor E78 inhibits the cuticle formation in the molting process of spider mite, Tetranychus urticae.

The two-spotted spider mite, Tetranychus urticae, is an important pest mite in agriculture worldwide. E78, as a member of the nuclear receptor superfamily and a downstream responsive gene of ecdysteroids, plays a crucial role in regulating physiological behaviors such as development and reproduction in insects. However, its function in mites remains unclear. The aim of this study was to explore how E78 functions in the molting process of spider mites. In this study, reverse transcription quantitative polymerase chain reaction (RT-qPCR) experiments to analyze the expression pattern of TuE78 during the development of Tetranychus urticae, demonstrated that the expression level of TuE78 was higher during the molting state than that after the completion of molting, and it reached a peak expression level when the deutonymph mites entered the molting stage. RNA interference (RNAi)-mediated gene-silencing of TuE78 resulted in 95% deutonymph mite molt failure. A series of analysis under a light microscope, and scanning and transmission electron microscopy revealed that RNAi mites died within the exuvium without ecdysis, and that apolysis had started but the new cuticle was thin and the typical cuticular lamellae were absent, indicating blockage of the post-apolysial processes and explaining molt failure. Hence, transcriptome sequencing confirmed that the expression of cuticle protein and lipid metabolism-related genes was significantly affected after TuE78 silencing. This study demonstrated that TuE78 participates in the molting process of Tetranychus urticae by regulating the post-apolysial processes with the formation of new cuticle and successful ecdysis. This in turn suggests the potential of TuE78 as a target for pest mite control and provides a theoretical basis for further exploration of the molecular regulatory mechanism of spider mite molting. © 2024 Society of Chemical Industry. Published by John Wiley & Sons Ltd.

Assessing the Efficacy of Organic and Chemical Treatments for Varroa Mite Control in Macedonian Apiaries

Varroa destructor infestations pose a significant global threat to honeybee colonies, affecting bee populations and honey production. The purpose of this study is to assess the performance of Apis mellifera L. honeybee colonies under various control methods with a particular focus on critical parameters like mite dewdrop, honey production and colony growth. The study took place in a normal apiary in the Pelister district for a year from April 2021 to March 2022. There were three treatment groups: Group A got Amitraz (a chemical treatment), group M got formic acid (an organic treatment) and group K got nothing (a control group) to see how the treatments affected the bees. Regular monitoring assessed parameters including dropped mites and Varroa infestation levels with honey production evaluated seasonally. The results showed that both chemical and organic treatments successfully decreased the levels of Varroa mite infestation compared to the control group, while also noting differences in colony growth and honey production. The Amitraz treatment did prevent the mites from dropping, but it also slowed down the young's development. On the other hand, the formic acid treatment kept the brood's development healthy, suggesting that it might be a better way to get rid of varroa. This study shows how important it is to think about how treatments affect important colony parameters. It also calls for more research like longterm observations, to fully understand how treatments affect the health, development and longevity of bee families which will eventually lead to the creation of more effective combined pest control methods.

The salivary gland transcriptome of Varroa destructor reveals suitable targets for RNAi-based mite control.

The mite Varroa destructorAnderson and Trueman (Mesostigmata: Varroidae) has a dramatic impact on beekeeping and is one of the main causes of honey bee colony losses. This ectoparasite feeds on honey bees' liquid tissues, through a wound created on the host integument, determining weight loss and a reduction of lifespan, as well as the transmission of viral pathogens. However, despite its importance, the mite feeding strategy and the host regulation role by the salivary secretions have been poorly explored. Here, we contribute to fill this gap by identifying the salivary components of V. destructor, to study their functional importance for mite feeding and survival. The differential expression analysis identified 30 salivary gland genes encoding putatively secreted proteins, among which only 15 were found to be functionally annotated. These latter include proteins with putative anti-bacterial, anti-fungal, cytolytic, digestive and immunosuppressive function. The three most highly transcribed genes, coding for a chitin-binding domain protein, a Kazal domain serine protease inhibitor and a papain-like cysteine protease were selected to study their functional importance by reverse genetics. Knockdown (90%-99%) by RNA interference (RNAi) of the transcript of a chitin-binding domain protein, likely interfering with the immune reaction to facilitate mite feeding, was associated with a 40%-50% decrease of mite survival. This work expands our knowledge of the host regulation and nutritional exploitation strategies adopted by ectoparasites of arthropods and allows the identification of potential targets for RNAi, paving the way towards the development of new strategies for Varroa mite control.

Modern Spraying Techniques For Grape Vineyards: A Review

During crop production, the most crucial techniques are being used for plant protection. Applying pesticides requires much more expertise and understanding than any other agricultural job, regardless of the crop being treated or the tools utilised. This is particularly applied to insect, disease, and mite control sprays in grapevines.

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

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

Effects of field releases of Neoseiulus barkeri on Megalurothrips usitatus abundance and arthropod diversity

Megalurothrips usitatus (Bagnall) (Thysanoptera: Thripidae) is an important pest in Vigna unguiculata (L.) Walp. Neoseiulus barkeri (Hughes) (Acari: Phytoseiidae) is widely used for control of pest mites and insects worldwide. We evaluated its effect on M. usitatus when predators (N. barkeri) or insecticides (Spinetoram) were applied in the fields. Neoseiulus barkeri Hughes consumed 80% of M. usitatus prey offered within 6 h, and predation showed Type III functional response with prey density. The maximum consumption of N. barkeri was 27.29 ± 1.02 individuals per d per arena (1.5 cm diameter), while the optimal prey density for the predatory mite was 10.35 ± 0.68 individuals per d per arena (1.5 cm diameter). The developmental duration of N. barkeri fed with M. usitatus was significantly shorter than those fed with the dried fruit mite, Carpoglyphus lactis (L.) (Acari: Astigmata). In field trials, the efficiency of N. barkeri against M. usitatus was not significantly different from that of applications of the insecticide spinetoram. Biodiversity of other insects in treated fields was assessed, and there were 21 insect species in garden plots treated with N. barkeri releases. The total abundance (N), Shannon’s diversity index (H), Pielou’s evenness index (J) and Simpson’s diversity index (D) of the garden plots treated with predatory mites were all significantly higher than that in the garden plots treated with spinetoram, where we found no species of predators or parasitoids and 7 herbivores. Our results show that N. barkeri is a potential means to control M. usitatus while preserving arthropod diversity at the level of treated gardens.

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

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

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

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

Varroa mite removal from whole honey bee colonies by powdered sugar dusting is enhanced by crowding and mechanical agitation of treated workers

The honey bee parasite, Varroa destructor, is susceptible to removal by dusting agents that physically interfere with its ability to cling to its phoretic hosts. Here we describe modifications to established powdered sugar dusting techniques that modestly increased mite separation from hosts and allowed for greater reductions in whole colony mite infestation rates. These modifications increased body-to-body contact through crowding and mechanical agitation to supplement dusting effects on mite removal. Adult workers were isolated in a screened sugar shake box outside the colony, dusted with powdered sugar, then carefully shaken and bounced in crowded piles for one minute to separate mites from their hosts. Whole colony powdered sugar shake treatments resulted on average in a 92% reduction in post-treatment mite infestation rates over three successive mite treatments. Our modifications provided effective mite control comparable to the miticide Apiguard (thymol) without discernable negative effects on colonies. Four months after treatment, powdered sugar shake treated colonies had relatively similar-sized adult worker and brood populations as Apiguard treated colonies and larger adult populations than controls. Colonies also maintained queens and reared relatively few queen cells across treatments. Further comparisons of method components revealed that mechanical agitation of crowded workers enhanced mite separation from hosts due to powdered sugar dusting. Mechanical agitation alone only modestly increased mite separation compared to controls; however, high levels of mite separation associated with sugar dusting increased with agitation. These modified methods provide a rapid if laborious technique for reducing mite populations without chemical residues from restricted miticides.

RNA interference as a next-generation control method for suppressing Varroa destructor reproduction in honey bee (Apis mellifera) hives.

The Varroa mite (Varroa destructor) is considered to be the greatest threat to apiculture worldwide. RNA interference (RNAi) using double-stranded RNA (dsRNA) as a gene silencing mechanism has emerged as a next-generation strategy for mite control. We explored the impact of a dsRNA biopesticide, named vadescana, designed to silence the calmodulin gene in Varroa, on mite fitness in mini-hives housed in a laboratory. Two dosages were tested: 2 g/L dsRNA and 8 g/L dsRNA. Vadescana appeared to have no effect on mite survival, however, mite fertility was substantially reduced. The majority of foundress mites exposed to vadescana failed to produce any offspring. No dose-dependent effect of vadescana was observed, as both the low and high doses inhibited mite reproduction equally well in the mini-hives and neither dose impacted pupal survival of the honey bee. Approximately 95% of bee pupae were alive at uncapping across all treatment groups. These findings suggest that vadescana has significant potential as an effective alternative to conventional methods for Varroa control, with broader implications for the utilization of RNAi as a next-generation tool in the management of pest species. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Varroa destructor economic injury levels and pathogens associated with colony losses in Western Canada

IntroductionThe honey bee parasitic mite, Varroa destructor, is considered the main factor associated with winter colony losses. To control this mite, beekeepers must implement Integrated Pest Management (IPM) strategies. An effective IPM strategy is based on timely monitoring of mite levels to treat the colonies when the mites reach an economic threshold and before they grow to damaging levels (economic injury level). Additionally, concerns have been raised about the possible interaction between V. destructor and other stressors; stressors acting additively or synergistically may lead to high colony mortality.MethodologyVarroa destructor levels were recorded in colonies from five regions of British Columbia, Canada: Lower Mainland, Kootenay, Okanagan, Cariboo, and Peace. Mite levels were analyzed for associations with colony strength and mortality, as well as with other pathogens that were identified using total RNA sequencing.ResultsThe Kootenay and Lower Mainland regions had the highest V. destructor levels in the fall (3.38±0.65 and 2.51±0.57, respectively) followed by the Okanagan (1.54±0.36), Cariboo (1.31±0.39), and Peace (0.66±0.25) regions. The Peace region had a significantly lower proportion of dead colonies than the other regions. Varroa destructor levels in the fall significantly predicted odds of colony mortality in the spring. Colonies with ≥ 1% mite infestation in the fall (August) had a significantly higher mortality rate (p=0.005) compared to colonies with <1% mite levels. Therefore, treatment is recommended above that threshold. Also, deformed wing virus-B levels were 8.4 times higher than those of deformed wing virus-A variant in all the regions and were highest in the Kootenay region, which also had the highest rate of colony losses. Lastly, Malpighamoeba mellificae and Nosema (Vairimorpha) apis transcripts were identified along with other pathogens that deserve further investigation, including Apis mellifera filamentous virus, Apis rhabdovirus, Lake Sinai virus, Varroa tymo-like, and Apis mellifera solinvivirus 1.DiscussionThe dynamic nature of host-pathogen interactions requires frequent pathogen surveillance to determine the prevalence and levels of parasitic mites and associated infectious diseases, and their impact on honey bee health, not only in the regions of this study, but globally. Nevertheless, more studies are needed to determine the nature of the type of interaction between the identified pathogens and V. destructor. Also, more research is needed to evaluate their potential impact on colony survival, to provide accurate mite and disease control recommendations to beekeepers.

A novel spider venom peptide from the predatory mite Neoseiulus barkeri shows lethal effect on phytophagous pests

The long-term use of pesticides in the field, and the high fertility and adaptability of phytophagous mites have led to resistance problems; consequently, novel safe and efficient active substances are necessary to broaden the tools of pest mite control. Natural enemies of arthropods typically secrete substances with paralytic or lethal effects on their prey, and those substances are a resource for future biopesticides. In this study, two putative venom peptide genes were identified in a parasitic mite Neoseiulus barkeri transcriptome. Recombinant venom NbSP2 peptide injected into Tetranychus cinnabarinus mites was significantly more lethal than recombinant NBSP1. NbSP2 was also lethal to Spodoptera litura when injected but not when fed to third instar larvae. The interaction proteins of NbSP2 in T. cinnabarinus and S. litura were identified by affinity chromatography. Among these proteins, ATP synthase subunit β (ATP SSβ) was deduced as a potential target. Four binding sites were predicted between NBSP2 and ATP SSβ of T. cinnabarinus and S. litura. In conclusion, we identified a venom peptide with activity against T. cinnabarinus and S. litura. This study provides a novel component for development of a new biological pesticide.

Effects of natural treatments on the varroa mite infestation levels and overall health of honey bee (Apis mellifera) colonies.

The survival of the honey bee (Apis mellifera), which has a crucial role in pollination and ecosystem maintenance, is threatened by many pathogens, including parasites, bacteria, fungi and viruses. The ectoparasite Varroa destructor is considered the major cause of the worldwide decline in honey bee colony health. Although several synthetic acaricides are available to control Varroa infestations, resistant mites and side effects on bees have been documented. The development of natural alternatives for mite control is therefore encouraged. The study aims at exploring the effects of cinnamon and oregano essential oils (EOs) and of a mixed fruit cocktail juice on mite infestation levels and bee colony health. A multi-method study including hive inspection, mite count, molecular detection of fungal, bacterial and viral pathogens, analysis of defensin-1, hymenoptaecin and vitellogenin immune gene expression, colony density and honey production data, was conducted in a 20-hive experimental apiary. The colonies were divided into five groups: four treatment groups and one control group. The treatment groups were fed on a sugar syrup supplemented with cinnamon EO, oregano EO, a 1:1 mixture of both EOs, or a juice cocktail. An unsupplemented syrup was, instead, used to feed the control group. While V. destructor affected all the colonies throughout the study, no differences in mite infestation levels, population density and honey yield were observed between treatment and control groups. An overexpression of vitellogenin was instead found in all EO-treated groups, even though a significant difference was only found in the group treated with the 1:1 EO mixture. Viral (DWV, CBPV and BQCV), fungal (Nosema ceranae) and bacterial (Melissococcus plutonius) pathogens from both symptomatic and asymptomatic colonies were detected.

Effectiveness of sod and humus soil maintenance and biologized protection in intensive apple orchards (Malus domestica Borkh.) in the south of Russia

Application of intensive technologies in horticulture with a high mechanical and chemical load on soils and fruit plants leads to deterioration of soil properties, environmental pollution, and development of resistance among pathogens and phytophages. In this study, we aim to developing a biologized technology for apple tree cultivation using a sod and humus system of inter-row maintenance and biopreparations based on active strains of microorganisms, entomoacariphages, and pheromones. The research was conducted in 2019-2023 in intensive apple orchards of the central plain-steppe region of Crimea by the methods conventionally used in soil science, agrochemistry, horticulture, and plant protection. The use of a mixture of cereal-legume grasses in combination with microbiological fertilizers based on nitrogen-fixing microorganisms was found to increase apple yields by 11–12 t/ha, or 64 % compared to the control, by increasing the number of fruits and the average weight of one fruit. A positive balance of nutrition elements in soil with an intensity of 135-270 % was established. The efficiency of controlling the number of phytophages and pathogen harmfulness through the integrated use of biological and biotechnical methods was shown. Thus, the “attract-and-kill” method for Cydia pomonella L. pheromones demonstrated a 98 % efficiency along with a reduction in pesticide load to 7.7 kg/ha season by the preparation. Release of phitoseiid mites for control of tetranychus mites by the method of seasonal colonization provides for a reduction and retention of phytophagous population at the economic threshold of harmfulness during the entire vegetation period. The use of fungicides based on pathogenic bacteria of the Bacillus genus and antagonist fungi of the Trichoderma genus against scab is eff ective only in the years unfavorable for the development of the disease. The results obtained form the basis for a biologized resource-saving technology for exploitation of intensive apple orchards. This technology contributes to increased soil fertility, reduced chemical and pesticide load, and increased productivity of horticultural agrocenosis under the conditions of the Crimea and southern Russia.

Honey bee (Apis mellifera) nurse bee visitation of worker and drone larvae increases Varroa destructor mite cell invasion.

The life cycle of Varroa destructor, the ectoparasitic mite of honey bees (Apis mellifera), includes a dispersal phase, in which mites attach to adult bees for transport and feeding, and a reproductive phase, in which mites invade worker and drone brood cells just prior to pupation to reproduce while their bee hosts complete development. In this study, we wanted to determine whether increased nurse bee visitations of adjacent drone and worker brood cells would increase the likelihood of Varroa mites invading those cells. We also explored whether temporarily restricting the nurses' access to sections of worker brood for 2 or 4h would subsequently cause higher nurse visitations, and thus, higher Varroa cell invasions. Temporarily precluding larvae from being fed by nurses subsequently led to higher Varroa infestation of those sections in some colonies, but this pattern was not consistent across colonies. Therefore, removing highly infested sections of capped worker brood could be further explored as a potential mechanical/cultural method for mite control. Our results provide more information on how nurse visitations affect the patterns of larval cell invasion by Varroa. Given that the mite's successful reproduction depends on the nurses' ability to visit and feed developing brood, more studies are needed to understand the patterns of Varroa mite invasion of drone and worker cells to better combat this pervasive honey bee parasite.

Early larval exposure to flumethrin induces long-term impacts on survival and memory behaviors of adult worker bees Apis mellifera

Flumethrin has been supplied as an acaricide for Varroa mite control in world-wide apiculture due to its low lethal effects on honey bees. However, little is known about the effects of short-term flumethrin exposure in the larval stage on adult life stage of bees involving survival status, foraging and memory-related behaviors. Here, we found that exposure to flumethrin at 1 mg/L during larval stage reduced survival and altered foraging activities including induced precocious foraging activity, decreased foraging trips and time, and altered rotating day-off status of adult worker bees using the radio frequency identification system. Furthermore, larval exposure at 1 mg/L flumethrin influenced the correct proboscis extension responses of 7-day-old worker bees and decreased homing rates of 20-day-old worker bees, suggesting that 1 mg/L flumethrin exposure at larval stage could affect memory-related behaviors of adult bees; meanwhile, three genes related to memory (GluRA, Nmdar1 and Tyr1) were certainly down-regulated varying different flumethrin concentrations (0.01, 0.1, and 1 mg/L). Combined with transcriptomic sequencing, differentially expressed genes involved in olfactory memory of adult bees were completely down-regulated under flumethrin exposure. Our findings highlight the unprecedented impact of short-term exposure of insecticides on honey bees in long-term health monitoring under field conditions.