Control of Varroa Destructor in Kazakhstan

Document Type : Original Articles

Authors

1 Kazakh National Agrarian Research University, Almaty, Kazakhstan

2 Al-Farabi Kazakh National University, Almaty, Kazakhstan

Abstract

Varroa mite is one of the most dangerous bee parasites and causes a lot of damage to the beekeeping industry. Several chemical and herbal medicines have been used to control this mite so far. In this study, the effects of Artemisia absinthium and Hypericum perforatum prescription to control Varroa mite were investigated. To this end, a total of 380 bee colonies in 5 areas in Kazakhstan were considered. The bitter wormwood herbs and Hypericum extracts were mixed in a ratio of 1:1, and then, prepared in a ratio of 1:10 with sugar syrup (100 ml infusion per 1 liter of sugar syrup). An amount of 200 ml of the prepared solution was used for 5-7 days per colony after medical collection and honey pumping. The percentage of mite infestation at the beginning and end of the experimental period, which was spring, summer, and autumn, and the number of worker mites and worker bees were determined daily. At the beginning of the experiment, the percentage of mite infestation in the experimental hives was not significantly different; however, at the end of the experiment, there was a significant difference between the experimental treatments. The use of a mixture of A. absinthium and H. perforatum extract significantly reduced the abundance index of Varroa mite to 0. Due to the adverse effects of chemical drugs and their high cost, it is recommended to use this extract to control Varroa mite contamination.

Keywords

Main Subjects


1. Introduction

The bee, like other living organisms, has been exposed to numerous pests and diseases during its lifetime, and one of the most common and dangerous pests that severely affect the population and performance of the bee colonies is the Varroa mite. This mite belongs to the Varroidae family and Varroa genus and feeds on adult larvae hemolymph, pupae, and bees at all stages of life. Mite colony infection causes the bees to lose weight, deform, or lose limbs, and sometimes make young bees die. Varroa mite is one of the most important and destructive pests of beehives that causes irreparable damage to the beekeeping industry ( 1 - 3 ). Numerous researchers have tried to find ways to control the parasite, and in this regard, such chemicals as Bayvarol, Apistan, Apigard, and Folbex have been reported to be able to prevent the outbreak of Varroa mite to some extent ( 4 - 6 ).

The Varroa mite is undoubtedly the most important pest and a serious threat to the beekeeping industry worldwide in the 21st century. Although some colonies are less affected, some colonies die within a few years despite a strong population. At present, there are negative trends in beekeeping in Kazakhstan, as a result of both socio-economic processes and the deterioration of the epidemiological and environmental situation. Brood diseases, such as Varroa tosis, Ascospherosis, and Nosemosis, are widely distributed in Kazakhstan. Varroa Destructor is the mite responsible for Varroa tosis (or varroosis), an external parasitic disease that attacks honeybee colonies (adult bees, especially the brood), which causes major economic losses to the beekeeping sector ( 7 ). Varroa mite can transmitpathogenic viruses to honey bees, often associated with colony collapse ( 8 - 10 ), and cause negative effects on the bee's immune responses ( 11 - 13 ).

There are numerous methods, including physical, biological, and chemical, which are used to control the Varroa destructor. Chemical pesticides (synthetic Varroa cides) are often employed to reduce the Varroa destructor population. Pyrethroids, such as Tau-Fluvalinate and Formamidine Amitraz are used for Varroa control in Kazakhstan ( 14 , 15 ). However, the use of chemical pesticides reveals numerous problems. This is the contamination of bee keeping products with their residues and metabolites ( 16 , 17 ), toxic and side effects of drugs on bees (18), also Varroa mites develop resistance to chemicals ( 19 , 20 ).

Today, various efforts are being exerted to replace herbal medicines with chemical ones in different countries ( 21 - 24 ). Among the medicinal plants that have been used in the control of Varroa mites by various researchers, including pepper, mint, chicory, and lavender ( 21 , 22 ). The two medicinal plants, namely Artemisia absinthium and Hypericum perforatum, have also been used for a long time due to their numerous properties. Artemisia absinthium, which is called with numerous synonymous Latin names, contains various compounds responsible for its biological activities. The most common compounds are thujyl alcohol esters, α-thujone, β-thujone, camphene, α-cadinene, guaiazulene (Z)-epoxyocimene, (E)-sabinyl acetate, (Z)-chrysantenyl acetate ( 25 ). Hypericum perforatum is a perennial flowering herb belonging to the Clusiaceae family, consists of approximately 500 species, and has been considered a medicinally valuable plant for over 2,000 years. The most important metabolites present in H. perforatum are phloroglucinols (hyperforin, hyperforin), naphtodianthrones (hypericin, pseudohypericin), flavonoids (rutin, quercetin, quercitrin, isoquercitrin, hyperoside, and amentoflavone), phenolic acids, and small amounts of essential oil ( 26 , 27 ).

The control of Varroa jacobsoniover Apis mellifera L. was easily achieved during the 1980s with the production of effective acaricides (Varroadestructor), and it appeared that the Varroa mite problem was solvable; however, experimental results showed that the mite-resistant line caches have been created. Resistance of Varroa mite to fluovinate acetate (an effective Pyrethroid acaricide against Varroa mite, of which Apistan is a well-known example) was reported first in Italy and then in other countries. Gradually, it became clear that only a small number of chemical acaricides were suitable for controlling mites. Fumisan also comes in the form of wood strips. Their width, length, and thickness are25 mm, 2 cm, and 1 mm, which come in 10 pcs in a package. They are infused with acaricide, a substance that kills ticks. The active ingredient in Fumisana is fluvalinate.

The effectiveness of miticides is greatly influenced by the physiological condition of bee families, weather, and natural climatic conditions. In this regard, it is necessary to study the involvement of bees with Varroa tosis and the effectiveness of miticides used to control bees in the conditions of Kazakhstan. This study aimed to evaluate the different acaricides regarding the duration (days) of effectivenessand compare with control (i.e., untreated group of honey bee colonies).

2. Materials and Methods

2.1. Site Location

This study was conducted at the laboratory of Anti-Parasitic Biotechnology, Department of Biological Safety, Kazakh National Agrarian University, Kazakhstan, and on the apiary of the Almaty, Turkestan, and East Kazakhstan regionsfrom 2018 to 2021 (Figure 1). In this experiment, raw data were obtained from diagnostic and experimental therapies. A total of 380 bee colonies from the native population were used to determine the effectiveness of the recommended drugs for the control of Varroa mites. Studies were carried out both on barren bee families and families with a spread in the summer and autumn periods.

Figure 1. Site locations1Karasai district, 2Enbekshikazakh district, 3Talgar district, 4Tole bi district, 5Altai district

2.2. Treatment Preparation

In this experiment, the treatment methods included infusion of herbal solution from bitter wormwood herbs (A.absinthium) and H. perforatum. The bitter wormwood herbsand Hypericumextracts were mixed in a ratio of 1:1, and then, prepared in a ratio of 1:10 with sugar syrup (100 ml infusion per 1 liter of sugar syrup). An amount of 200 ml of the prepared solution was used for 5-7 days per colony after medical collection and honey pumping.This experiment was performed using "Methodological recommendations for the study of drugs and methods for combating Varroa tosis of bees" ( 28 ) and methodological guidelines for the production of experiments in beekeeping ( 29 , 30 ).

Bees were kept in 16-frame hives, and oxalic acid was applied for the treatment of bees. The gluing bees in barren families were determined by sampling bees from the center of the nest into a folded sheet of paper in the amount of 100-150 individuals, in families with a spread by a sampling of 100 doll bees in the sealed melt. The collected samples were stored in the freezer.The experimental treatments were sprayed using a syringe in the space between the bee frames (Figures 2-4).

Figure 2. Treatment of bees with a syringe

Figure 3. Bees and apiary

Figure 4. Bees affected by tick-borne Varroa tosis

The presence and number of mites on the bees were determined individually or by group sampling method. In a group study, a container of honey, a net or gauze (to prevent mites to pass through), a small amount of washingpowder, and a piece of plastic or cloth were prepared for the determination of the number of bees' mites( 31 ).Bee samples were placed in heat-resistant cups with a capacity of 300-400 ml, 3-5 g of washing powder was added, andthen, 300-400 ml of boiling water was poured and stirred periodically for 5-10 min. Afterward,a solution with the bees was poured into the device, where the mites settled on the bottom of the

funnel. Subsequently, the clamp was removed, the solution was drained into a used glass, and the number of mites was counted. Infected cells were sampled by opening the cell lid with a scalpel and examining the pupa individually. Only adult Varroa mites were considered. Once the parasites were identified, the data of bees or pupae were recorded with an abundance index, calculated by the number of mites ( 32 ). The obtained data were subjected to biometric analysis according to the methods proposed by Chiou ( 33 ).

2.3. Determining Varroa mite in Honey Bee Colonies

The degree of infection of bee colonies in Varroa mites was determined by the following formula:

N=MS×100

where:

N: Varroa mite infestation levels in honey bee colonies (number of mites per 100 bees);

M: number of mites found

S: number of bees in the sample

The level of infestation of bee colonies in Varroa mites is low, medium, or high if there are up to 10, up to 20, or more than 20 mites per 100 bees, respectively.

2.4. Statistical Analyses

The data were analyzed in statistical software Minitab (version 17), and the comparisons of means were performed using the independent T-test. Excel software was used to draw graphs and tables.

3. Results

3.1. General Characteristics of Apiary

In this study, 380 bee colonies were studied located in zones Almaty, Turkestan, and East Kazakhstan regions, Kazakhstan. Table 1 showed the apiary, area/district, number of bee colonies, number of infected colonies, and percentage of infection. To pre-diagnose and determine the spread of Varroa tosis on the apiary farms of various regions from 2018 to 2021, studies were carried out by clinical examination of bee families.The highest levels of Varroa mite infection are related to Talgar district (15%) and Enbekshikazakh district (12.86%) regions, Kazakhstan, and the lowest levels of pollution are related to Tole bi district (0.00%) and Karasai district (3.33%), Kazakhstan.

Apiaries Region/District Number of honey bee colonies Infestation level of Varroa
Number of Infected bee colonies Infestation (%)
P.P.Konovalov Almaty region, Karasai district, Gorniysadovod 120 4 3.33
V.S Savarovsky Almaty region, Enbekshikazakh district, Issyk city 70 9 12.86
Bisen Ata Almaty region, Talgar district, Taldybulak village 20 3 15.00
M.Yrysbaev Turkestan region, Tole bi district, Kazakhstan settlement 80 0 0.00
Arashy East Kazakhstan region, Altai district, Putintsevo village 90 5 5.56
Total 380 21 5.53
Table 1. Results of the study of bee colonies for varroatosis mites

3.2. Percentage of hives Infested with Varroa Mites

In different seasons, the percentages of infestation of experimental hives in different areas was determined at the beginning and end of the experimental period and showed that at the beginning of the experiment there was no significant difference in terms of Varroa mite infestation; however, at the end of the experiment, a significant difference was observed using experimental treatments (Table 2). Based on figure 5, the infestation intensities of adult and larvae bees in spring, summer, and autumn were calculated at 1.5, 1.7, and 2.1, 1.3, 1.6, and 1.9, respectively.

Ticks detected Spring (April) Summer (June) Autumn (October)
Total II1 Total II Total II
On bees 375.00 1.50 425.00 1.70 525.00 2.10
On larva 325.00 1.30 400.00 1.60 475.00 1.90
Table 2. Seasonal intensity of invasion of bees by varroatosis

Figure 5. Seasonal infestation intensity of bees and larva by Varroa mite

The infection intensity rates of adult bees'samples in spring, summer, and autumn were estimated at1.5%, 1.7%, and 2.1%, respectively. At the beginning of the queen spawning season (spring), with increasing hive activity and reproduction, the percentage of intensity of infection increased, which was also observed in bee larvae. A sampling of Varroa mites from the mentioned apiaries showed that they were 1.13 and 1.40 greater in summer and autumn than in spring, respectively, the intensity of infection was increased, and this trait on the larvae increased by 1.23 (summer) and 1.46 (autumn) times.

The effect of plant extract on the abundance index before and after the experiment was shown in table 3. According to different samplings, the abundance index before using experimental treatments varied from 0.01 to 0.05, which reached 0after using plant extracts. Nevertheless, in the control group, the abundance index increased, and efficiency in processing was calculated to be 100 and 0.00 in the experimental and control groups, respectively.

Family group n Abundance index Efficiency in processing (%)
Before treatment After treatment
Experimental 45 0.02 0.00 100
36 0.01 0.00 100
39 0.01 0.00 100
16 0.05 0.00 100
Control 12 0.03 0.04 0.00
7 0.02 0.02 0.00
3 0.03 0.04 0.00
Table 3. Botanical efficiency in the summerseason

The effect of plant extract on the abundance index was also calculated before and after the experiment in autumn (Table 4). The results showed that the abundance index before using the experimental treatments ranged from 0.036 to 0.082, which reached 0after using plant extracts. Nonetheless, in the control group, the abundance index increased from 0.019 to 0.068, and efficiencies in processing were calculated to be 100 and 0.00 in the two experimental and control groups, respectively.

Family group n Abundance index Efficiency in processing (%)
Before treatment After treatment
Experimental 48 0.064 0.00 100
24 0.036 0.00 100
25 0.082 0.00 100
Control 15 0.021 0.019 0.00
27 0.048 0.046 0.00
23 0.056 0.068 0.00
Table 4. Botanical drug efficiency in the autumn season

Currently, a large number of drugs have been proposed for the therapy of bee families infested with Varroa tosis. Beekeepers, when choosing drugs, often focus on information emanating from product manufacturers. However, to the best of our knowledge, there is little data on the efficacy of acaricides used to treat bees. In the conditions of the apiary farms of Talgar district, Enbekshikazakh district, Karasai district, Tolebi district, and Altai district regions, Kazakhstan, the anti-adhesive activity of botanical drug composition and Fumisan were studied in the present research (Figure 4). Table 5 showed that the use of Fumisanin both experimental and control groups was as effective as herbal medicines and reduced the abundance index in the experimental group from 0.02 to 0.07 and reached 0.00.

Family group n Abundance index Efficiency in processing (%)
Before treatment After treatment
Experimental 46 0.02 0.00 100
4 0.07 0.00 100
5 0.02 0.00 100
Control 8 0.01 0.02 0.00
17 0.02 0.03 0.00
33 0.02 0.03 0.00
Table 5. Fumisan efficiency in the autumnseason

4. Discussion

The results of the colonies involved in Varroa mites in spring, summer, and autumn indicated that after the beginning of the bee breeding season in spring, the number of mites also increased over time. In most parts of the world, including Kazakhstan, hives infected with Varroa mites are treated with chemical drugs. In addition to adverse effects on bee colonies, chemical drugs remain in bee products. Moreover, if such chemicals are used, drug resistance develops in bees. The results of this study showed that the use of A. absinthium and H. perforatum led to the proper control of the involved apiaries of Varroa mites. α-Thujone is commonly considered to be the principal active ingredient of A. absinthium and toxic principle in absinthe ( 34 ) and it was one of the two most toxic monoterpenoids tested against western corn rootworm larvae. Public suspicion of synthetic pharmaceuticals and pesticides has led to the growing popularity of herbal medicines and botanical insecticides even though they have not been subjected to the same severe tests of safety and evaluation of toxicological mechanisms ( 35 - 37 ).

The use of H. perforatum extracts also controlled the infection of apiary mites. Hypericum perforatum has a significant effect on reducing mite infestation in bees due to its composition of essential oils, phenols, and terpenes. Essential oils are one of the chemical groups in plant extracts that have a significant effect on reducing bee and Varroa infection in bees ( 38 ). The compounds of phenols and terpenic in medicinal plant extracts also affect various diseases of bees, including antifungal activity. Varroa mite control strategy using medicinal plants has increased in recent years ( 5 , 39 , 40 ).

The plant compounds in the tobacco plant were also effective at controlling Varroa mites due to the active ingredients of nicotine, nicoteine, and nicotelline ( 23 , 41 , 42 ). Peganum harmala has long been used among Iranians as a disinfectant due to alkaloid compounds, such as harmine, harmalin, and harmalol ( 43 , 44 ). Thyme kotschyonus has a disinfectant role due to its thymol and has been traditionally used in various apiaries ( 45 ).

As a result of this study about the effectiveness of drugs, it was established that in the conditions of the Almaty, Turkestan, and East Kazakhstan regions, long-acting preparations based on fluvalinate, Fumisan showed the high acaricidal effects. Considering that the active ingredient is 10 times lower in the Fumisan preparation than in Apistan, and the recommended treatment period in the presence of a melt is twice shorter (21-25 days), Fumisan is undoubtedly safer from the point of view of contamination of beekeeping products with residues of the active ingredient. It is impossible to ignore the significant difference in the price of these drugs (Fumisan is 10 times cheaper), which is important for the budget of beekeepers. Therefore, based on the results of the conducted studies, it can be concluded that botanical drugs should be in a ratio of 1:1 mixed with sugar syrup (1:10), which has high acaricidal efficiency in Varroa tosis of bees.

Authors' Contribution

Study concept and design: A. A. M.

Acquisition of data: A. A. M.

Analysis and interpretation of data: G. T.

Drafting of the manuscript: M. N.

Critical revision of the manuscript for important intellectual content: A. A. M.

Statistical analysis: A. A. M.

Administrative, technical, and material support: A. A. M.

Ethics

All the procedures were approved by the Ethics Committee at the Kazakh National Agrarian Research University, Almaty, Kazakhstan.

Conflict of Interest

The authors declare that they have no conflict of interest.

References

  1. Khan KA, Ghramh HA. An investigation of the efficacy of hygienic behavior of various honey bee (Apis mellifera) races toward Varroa destructor (Acari: Varroidae) mite infestation. J King Saud Univ Sci. 2021; 33(3):101393.
  2. Sabahi Q, Morfin N, Nehzati-Paghaleh G, Guzman-Novoa E. Detection and replication of deformed wing virus and black queen cell virus in parasitic mites, Varroa destructor, from Iranian honey bee (Apis mellifera) colonies. J Apic Res. 2020; 59(2):211-7.
  3. Sajid ZN, Aziz M, Bodlah I, Rana RM, Ghramh HA, Khan KA. Efficacy assessment of soft and hard acaricides against Varroa destructor mite infesting honey bee (Apis mellifera) colonies, through sugar roll method. Saudi J Biol Sci. 2020; 27(1):53-9.
  4. Imdorf A, Bogdanov S, Ochoa RI, Calderone NW. Use of essential oils for the control of Varroa jacobsoni Oud. in honey bee colonies. Apidologie 1999; 30(2-3):209-28.
  5. Kloucek P, Smid J, Flesar J, Havlik J, Titera D, Rada V, et al. In vitro inhibitory activity of essential oil vapors against Ascosphaera apis. Nat Prod Commun. 2012; 7(2):1934578X1200700237.
  6. Wallner K. Varroacides and their residues in bee products. Apidologie. 1999; 30(2-3):235-48.
  7. Formato G. Main bee diseases: Good beekeeping practices. FAO Roma, Italy. 2018.
  8. Berthoud H, Imdorf A, Haueter M, Radloff S, Neumann P. Virus infections and winter losses of honey bee colonies (Apis mellifera). J Apic Res. 2010; 49(1):60-5.
  9. Highfield AC, El Nagar A, Mackinder LC, Noël LM-L, Hall MJ, Martin SJ, et al. Deformed wing virus implicated in overwintering honeybee colony losses. Appl Environ Microbiol. 2009; 75(22):7212-20.
  10. Nazzi F, Brown SP, Annoscia D, Del Piccolo F, Di Prisco G, Varricchio P, et al. Synergistic parasite-pathogen interactions mediated by host immunity can drive the collapse of honeybee colonies. PLoS Pathog. 2012; 8(6):e1002735.
  11. Gregory PG, Evans JD, Rinderer T, De Guzman L. Conditional immune-gene suppression of honeybees parasitized by Varroa mites. J Insect Sci. 2005; 5(1)
  12. Navajas M, Migeon A, Alaux C, Martin-Magniette M, Robinson G, Evans JD, et al. Differential gene expression of the honey bee Apis mellifera associated with Varroa destructor infection. BMC Genom. 2008; 9(1):1-11.
  13. Yang X, Cox-Foster DL. Impact of an ectoparasite on the immunity and pathology of an invertebrate: evidence for host immunosuppression and viral amplification. Proc Natl Acad Sci. 2005; 102(21):7470-5.
  14. Kanga LH, Adamczyk J, Marshall K, Cox R. Monitoring for resistance to organophosphorus and pyrethroid insecticides in Varroa mite populations. J Econ Entomol. 2010; 103(5):1797-802.
  15. Millán‐Leiva A, Marín Ó, Christmon K, vanEngelsdorp D, González‐Cabrera J. Mutations associated with pyrethroid resistance in Varroa mite, a parasite of honey bees, are widespread across the United States. Pest Manag Sci. 2021.
  16. Bogdanov S. Contaminants of bee products. Apidologie. 2006; 37(1):1-18.
  17. Wu C, Liu X, He M, Dong F, Wu X, Xu J, et al. Quantitative determination of pyriproxyfen and its metabolite residues in bee products of China using a modified QuEChERS approach with UPLC-MS/MS. Ecotoxicol Environ Saf. 2021; 220:112388.
  18. Simeunovic P, Stevanovic J, Cirkovic D, Radojicic S, Lakic N, Stanisic L, et al. Nosema ceranae and queen age influence the reproduction and productivity of the honey bee colony. J Apic Res. 2014; 53(5):545-54.
  19. Floris I, Satta A, Garau VL, Melis M, Cabras P, Aloul N. Effectiveness, persistence, and residue of amitraz plastic strips in the apiary control of Varroa destructor. Apidologie. 2001; 32(6):577-85.
  20. Maggi MD, Ruffinengo SR, Negri P, Eguaras MJ. Resistance phenomena to amitraz from populations of the ectoparasitic mite Varroa destructor of Argentina. Parasitol Res. 2010; 107(5):1189-92.
  21. Damiani N, Gende LB, Maggi MD, Palacios S, Marcangeli JA, Eguaras MJ. Repellent and acaricidal effects of botanical extracts on Varroa destructor. Parasitol Res. 2011; 108(1):79-86.
  22. Iglesias A, Mitton G, Szawarski N, Cooley H, Ramos F, Arcerito FM, et al. Essential oils from Humulus lupulus as novel control agents against Varroa destructor. Ind Crops Prod. 2020; 158:113043.
  23. Rajiter A. Preliminary results on treatment of varroa infected honey bee colonies with tobacco smoke. Bee World. 1983; 64(3):63-5.
  24. Razavi SM, Asadpour M, Jafari A, Malekpour SH. The field efficacy of Lepidium latifolium and Zataria multiflora methanolic extracts against Varroa destructor. Parasitol Res. 2015; 114(11):4233-8.
  25. Szopa A, Pajor J, Klin P, Rzepiela A, Elansary HO, Al-Mana FA, et al. Artemisia absinthium L. —Importance in the history of medicine, the latest advances in phytochemistry and therapeutical, cosmetological and culinary uses. Plants. 2020; 9(9):1063.
  26. Kladar N, Mrđanović J, Anačkov G, Šolajić S, Gavarić N, Srđenović B, et al. Hypericum perforatum: Synthesis of Active Principles during Flowering and Fruitification—Novel Aspects of Biological Potential. Evid Based Complement Alternat Med. 2017; 2017
  27. Klemow KM, Bartlow A, Crawford J, Kocher N, Shah J, Ritsick M. Herbal medicine: biomolecular and clinical aspects. CRC Press. 2011; 2(11):211-28.
  28. Rosenkranz P, Aumeier P, Ziegelmann B. Biology and control of Varroa destructor. J Invertebr Pathol. 2010; 103:S96-S119.
  29. Lippiatt BC. Selecting cost-effective green building products: BEES approach. J Constr Eng Manag. 1999; 125(6):448-55.
  30. Shagun YL. Methodical recommendation on economical evaluation of natural resources of bees. 2000.
  31. Stolbov NM, Vaskov HA. Tick detection apparatus Varroa. Beekeeping. 1976; 8:17.
  32. Beklemishev V. Populations and micropopulations of parasites and other associated organisms. Zool Zhurnal. 1959; 38(8)
  33. Chiou S-Y. Secure Method for Biometric-Based Recognition with Integrated Cryptographic Functions. BioMed Res Int. 2013; 2013:623815.
  34. Arnold WN. Vincent van Gogh and the thujone connection. Jama. 1988; 260(20):3042-4.
  35. Coats JR. Risks from natural versus synthetic insecticides. Annu Rev Entomol. 1994; 39(1):489-515.
  36. Matthews HB, Lucier GW, Fisher KD. Medicinal herbs in the United States: research needs. Environ Health Perspect. 1999; 107(10):773-8.
  37. Anonymous. Medicinal herbs: NTP extracts the facts. Environ Health Perspect. 1999; 107:604-5.
  38. Ruffinengo SR, Maggi M, Fuselli S, Floris I, Clemente G, Firpo NH, et al. Laboratory evaluation of Heterothalamus alienus essential oil against different pests of Apis mellifera. J Essent Oil Res. 2006; 18(6):704-7.
  39. Boudegga H, Boughalleb N, Barbouche N, Ben Hamouda MH, Mahjoub ME. In vitro inhibitory actions of some essential oils on Ascosphaera apis, a fungus responsible for honey bee chalkbrood. J Apic Res. 2010; 49(3):236-42.
  40. Nardoni S, D’Ascenzi C, Rocchigiani G, Papini RA, Pistelli L, Formato G, et al. Stonebrood and chalkbrood in Apis mellifera causing fungi: in vitro sensitivity to some essential oils. Nat Prod Res. 2018; 32(4):385-90.
  41. De Ruijter A. Beekeeping techniques: Tobacco smoke can kill varroa mites. Bee World. 1982; 63(3):138.
  42. De Ruijter A, vd Eijnde J. Detection of Varroa mite in the Netherlands using tobacco smoke. Bee World. 1984; 65(4):151-4.
  43. Parchin RA, Bahraminejad S, Parchin MA, Ebadollahi A. Toxic effect of a selection of medicinal plant products against the parasitic bee mite Varroa destructor. J Med Plant Res. 2012; 6(14):2807-11.
  44. Ur Rehman J, Wang X, Johnson MW, Daane KM, Jilani G, Khan MA, et al. Effects of Peganum harmala (Zygophyllaceae) seed extract on the olive fruit fly (Diptera: Tephritidae) and its larval parasitoid Psyttalia concolor (Hymenoptera: Braconidae). J Econ Entomol. 2009; 102(6):2233-40.
  45. Shaddel-Telli A, Maheri-Sis N, Aghajanzadeh-Golshani A, Asadi-Dizaji A, Cheragi H, Mousavi M. Using medicinal plants for controlling Varroa mite in honey bee colonies. J Anim Vet Adv. 2008; 7(3):328-30.