Diagnostic Survey of Honey Bee Disease in East Wollega Zone, Oromia National Regional State, Ethiopia

Keywords

Honeybees; Disease; Pests; Prevalence; Infestation; Oromia

Abstract

The study was conducted to assess the honey bee pests, predators, and diseases in the selected districts of East Wollega Zone. A cross-sectional study design was used for this study to determine honeybee disease and pests. A questionnaire survey and laboratory diagnostic methods were used for the study. The questionnaire was administered to 104 beekeepers (97.1% males). Totally 52 beekeeping sites and two honeybee colony samples from each beekeeper sites, totally (104 honeybee colonies), were collected from frame box hives for laboratory diagnosis. The major cause of honey bee colony and yield decrease ranked by respondents were 1st pets and predators, 2nd Honeybee diseases and 3rd in appropriate agrochemical application. Majority of honeybee colonies were infested by ant 538(21.3%), by beetles 378(14.9%) and by wax moth 315(12.5%), in all districts. Among all pest and predators listed by respondents honeybee colonies were absconded by ants 213(8.4%), wax moth 194(7.7%) and by beetles 193(7.6%). After having identified the major pests, beekeepers were requested to rank them in order of their importance and the result indicated that Ants (1st), beetles (2nd), Wax moth (3rd) and honey badgers (4th) were the most harmful pests in order of degree of their importance. 52 beekeeping sites and 104 honeybee colonies were examined for major honeybee parasites (Varroa mites, bee lice, and tracheal mites), adult honeybee diseases (Nosema and Amoeba) and brood diseases (Chalk brood, American and European Foul brood) with their prevalence in the study area. However, AFB, EFB, SBD, and tracheal mite was not confirmed during the study period.

Citation

OBuli AA (2024) Diagnostic Survey of Honey Bee Disease in East Wollega Zone, Oromia National Regional State, Ethiopia. Int J Anim Sci 5: 8

INTRODUCTION

Ethiopia is endowed with diverse agro climatic features which favors for the growth of diverse natural and cultivated floral species supporting huge number of bee colonies [1-3]. Beekeeping is an economic activity of the agricultural sector and an environmentally sustainable production model, crucial for biodiversity and agriculture. Beekeeping provides additional income for many poor communities, creating new opportunities in rural areas, and improves the living conditions of many families. In addition, the pollination service provided by honeybees generates increases in crop yields and contributes to the balance of the ecosystem and biodiversity.

Like all other insects, honeybees (Apismellifera) are susceptible to pests and diseases. Honey bees suffer from a range of bacterial, fungal, microsporidian and viral pathogens, as well as ectoparasitic mites, which can all lead to poor colony health and colony loss. It is important for beekeepers to be aware of these disorders, to identify them and effectively manage disorders to maintain healthy colonies. This is particularly important because the health of one beekeeper’s colony can impact another beekeeper’s colony in the surrounding area. The honeybee population and its products decline from time to time by some factors like, honey bee disease, pests, predators, pesticide, environmental stress and genetic disorder [4].

The economic loss associated with the presence of honey bee diseases and pest lead to significant product lost. In the present time the major honeybee diseases, pests and predators and their rate of distribution are reported in Ethiopia [5]. However, there should be regular and wide-scale diagnostic survey to monitor the occurrence of new pests and disease affecting honeybee’s health. There is still insufficient evidence on the side effects of pests and diseases. Very importantly, a comprehensive strategic response to the recently occurred varroa mite threat in determining its thresholds, economic damages and behavioral attributes with devising control options are very important [6].

There are many honey bee diseases (bacterial, fungal, viral, microsporidia), parasites (mites), predators (bears, birds, humans), and pests (beetles, moths) that can adversely affect managed honey bee productivity and survival [7]. Colony strength and health status are regularly assessed, and samples are taken and checked for disease and parasite loads. The adequate methods for defining and assessing the causes of death of honey bee colonies are not well implemented. This makes it difficult to assign annual die-offs to specific causes, and that makes it difficult for beekeepers to know what problems should be demanding their greatest attention.

A well-defined list of symptoms for each honey bee pest, parasite, pathogen, and predator allows for differential diagnosis of honey bee pathologies. Due to this difficulty in diagnosing a problem, it will be necessary to collect and archive samples of bees regularly. Honey bee colony health has received considerable attention in recent years, with many studies highlighting multifactorial issues contributing to colony losses. Disease and weather are consistently highlighted as primary drivers of colony loss, yet little is understood about how they interact.

Consequently, the study was carried out directing to the general objective to create baseline data on the current status of honeybee colony health problems in East Wollega Zone designed with the specific objectives:

• To determine the occurrence and prevalence of honeybee diseases, pests and predators

• To determine the effect of honeybee diseases, pests and predators on honey bee colonies and their products in the study areas

MATERIALS AND METHODS

Description of the Study Area

The study was conducted in East Wollega Zone, Oromia Regional state at about 332km away from Addis Ababa, the capital city of Ethiopia. The zone is located at 36⁰ 30’00” to 36⁰ 45’00’’longitude and 9⁰ 05’00’’ to 9⁰ 15’00’’ latitude with elevation ranging from 1000m to 3207m. The annual rainfall of the zone ranged from 1500mm to 2200mm with mean annual temperature 15-20⁰C [8]. The study districts covered in this study were; Diga , Gida Ayana, Gobu Sayyo and Wayu Tuka. (Figure 1) 

Figure 1: Map of the study area

Study Design and Sampling Procedure

A cross-sectional study was conducted on honeybee colonies to assess the prevalence of common honeybee diseases, pests and predators by using microscopic examination for protozoa parasite and macroscopic examination for Varroa mite and bee louse from adult worker honey bee. Semi structured questionnaire was administered from each apiarist to assess honeybee pests and predators in the study area.

From each sampling localities, adult honeybee and if possible sealed brood samples were taken from sampled honeybee colonies. In the absence of sealed brood, empty old brood combs were taken to see the remnant symptoms of disease attacks. Moreover field observations were carried out on the presence of pests and the necessary records were carried out. In addition to this, beekeepers were asked if any occurrences of some diseases in the past (like chalk brood) but which is not now observed and their reports were recorded.

Adult Honeybee and Brood Sampling

A cross-sectional study was carried out in East Wollega Zone, in Diga, Gida Ayana, Gobu Sayo and Wayu Tuka, by considering beekeeping with transitional and modern beekeeping methods to identifying of the major type of pests & disease causes of significant economic loss in honey bees by observing and collecting samples from the colonies. Then, isolation and identification of bee diseases causing pathogens were conducted. Diagnosis was confirmed by integrating clinical and parasitological studies. To examine the prevalence and infestation rates of the onset of diseases and pests, two honeybee colonies considering every 52 beekeepers as one apiary site, totally 104 honeybee colonies samples were taken from all districts. The beekeeper should be 2km-5km far distant from each other. Internal and external inspection were done and adult honeybees and broods were taken for laboratory diagnoses. Finally, the prevalence for apiary level and infestation/ infection for colony level was calculated using (Vanenglesdorp et al., 2013) protocols:

Diagnosis for Major Honeybee Diseases and Pests

Field observation and diagnosis were conducted through colony inspections for major honeybee diseases including Nosema, Amoeba, Chalk brood, American foul brood, European foul brood (where there was suspected clinical symptoms). Besides field observations, laboratory testing for each type of diseases examination was conducted following the standard procedures for each honeybee diseases.

Laboratory Examination of Varroa destructor

The study followed the standard methods for Varroa detection [9]. From each sample of honeybee colonies, 250 adult honeybees were brushed off from the brood comb directly into a wide mouth plastic container. The collected adult bees were killed using 70% ethyl alcohol and placed in 10 ml of 1% detergent-water solution then vigorously shaken for 1 minute to dislodge mites. The mites were collected by filtering the solution through a ladle (8- to-12-mesh) which holds the mites back and discharge the solutions. The wire gauze was turned down to white paper on which the presence/ absence of the mite was examined and counted.

For brood examinations samples of 5 X 5cm brood comb areas from the drone and/or worker pupae broods were taken. About 100 pupae were randomly removed from their cells using forceps and checked for the presence of varroa mites on the worker and/ or drone pupae. The number of varroa mites observed in both diagnosis (adult and brood) were recorded.

Laboratory Examination of Tracheal Mite

Samples of 20-30 adult honeybees collected from colonies at random and preserved by adding by 70% alcohol. The head and first pair of legs of honeybees were removed using scissors. Transverse-section thoracic disks were sliced and placed directly in a small bottle containing 10-percent potassium hydroxide (KOH). The sliced thoracic disks in KOH were heated and stirred gently near to the boiling point for approximately 10 minutes until the soft internal tissues dissolved to expose tracheal rings. The disk-trachea suspension was examined for mite infestation under light microscope [10].

Laboratory Examination of Nosema and Amoeba diseases

As these two diseases affect the abdominal contents of adult honeybees, their sampling and diagnostic techniques are almost the same. Therefore, bee samples collected for either of the two can help to tell the condition or status of the other [11]. The samples of 60 bees should be collected in order to detect 5% of diseased bees with 95% confidence [12] and preserved in 70% alcohol until laboratory analysis. The abdomen of honeybees from each sample was cut and grounded in a mortar containing 5-10ml distilled water. The mortar and pestle were thoroughly cleaned before being used again. A loop of suspension were placed on microscopic slide using the sterilized loop and covered with cover slid. Then the suspension was examined under a light microscope.

Laboratory Examination of Chalk Brood Disease

Both external and internal inspection will be conducted for the presence of chalk brood clinical symptoms. Dry scales with white to dark colour moulds and chalk brood mummies will be carefully observed in the comb cells and on the bottom boards of the hives. Then mummies were moistened with distilled water and the supernatant was placed on a microscope slide ande xamined under the light microscope for spores or spore balls and cysts of Ascosphera apis [13].

Examination of American Foulbrood (AFB) and European Foulbrood (EFB)

In randomly selected apiaries about three and above colonies were inspected internally for major clinical symptoms of bacterial diseases with emphasis to AFB and EFB. Typical clinical symptoms such as irregular brood arrangement, sunken and dark capping with puncture holes, dead and decayed larvae with dark “scales” and slight to pronounced odor was examined for the occurrence of AFB in the colonies. Similarly, twisted larvae with creamy-white guts visible through the body wall, melted and yellow white larvae with unpleasant sour odour and loosely-attached brown scales were directly observed for the infected colonies by EFB. Furthermore, match stick test (stretch test) was employed to observe the robby thread stretching for the typical clinical symptoms of bacterial diseases.

From any suspected brood showing one of the above important clinical symptoms, brood smear samples was prepared on frosted end microscopic slide and legibly labeled for further laboratory diagnosis according to Primefact, 2009 (www.dpi.nsw.gov.au/primefacts). Both Nigrosine and Holstic milk test approach was conducted according to the procedure of Shimanuki et al. (2000) for the presence and protolytic reaction of gram+ spores, respectively. Samples will be examined under microscope for the presence of Paenibacillus larvae and Melissoccocus pluton in positive samples AFB and EFB, respectively using Zeiss AxioVert A.1 light microscope under oil immersion (magnification power of 100X)

Data Management and Statistical Analysis

The collected data were stored in Microsoft Excel and SPSS software programs (SPSS @, version 20) for analysis. The statistical analysis used in the study was varied depending on the type of variable and information obtained. Summarized data was presented in the form of tables and figures. The data collected through semi-structured questionnaires were analyzed using descriptive statistics and the ranking of the different types of beekeeping constraints, Common cause of honeybee colony and yield decrease, control method of bees from agrochemicals and the effect of pest and predators on honeybee colonies obtained in the study were done by using the rank index formula as described by [14].

Rank index=sum of (5 X number of household ranked first +4 X number of household ranked second +3 X number of household ranked third +2 X number of household ranked fourth +1 X number of household ranked fifth) for an individual reason divided by the sum of (5 X number of household ranked first +4 X number of household ranked second +3 X number of household ranked third +2 X number of household ranked fourth +1 X number of household ranked fifth) for overall reasons.

RESULT AND DISCUSSION

Socio-Demographic Characteristics of the Respondent

From 104 sample households, about 2.9% female and 97.1% male headed. About 45.2% of respondent’s age ranges from 18 to 42. Concerning to occupational status of beekeepers, 99% were farmers. Most of the beekeepers practice beekeeping as a side of crop production in the study area. This result shows that beekeepers in the study areas were more in productive age. Based on the education status of respondents, about 40.4%, 34.6% and 23.1% of respondent beekeepers have attended elementary, secondary school and others can read and write respectively. Beekeeping activity in the study area were practiced by both educated and non-educated beekeepers, but beekeepers with the better educational backgrounds were more productive since they adopted efficient beekeeping technologies of beekeeping (Table 1).

Table 1: Socio- demographic characteristics of households

Beekeeping Activities and Potentials

Based on respondents and visual observation the beekeeping activities in all districts have been practiced sideline with other agricultural activities (100%). There were no any respondents who depend only on beekeeping. Most beekeepers were started beekeeping before 1994 (92.3%) with traditional beehives, 1994-2004 (49.0%) with traditional beehive and transitional beehives, 1994-2004 (29.8%) with transitional beehives, 2005-2015 (35.6%) with movable frame box beehives and after 2015(40.4%) with movable frame box and (28.9%) with transitional beehives. This in indicate the use of modern beekeeping technologies were increasing that beekeepers were related within age of between 31-42 years (Table 2). The beekeeping experience has positive correlation with usage of improved beekeeping technologies (P<0.01). Most of the respondents were shifting their traditional beekeeping to transitional and frame box beekeeping systems.

Table 2: Beekeeping activities and potentials

Sources of Honeybee Colony

The result indicates the sources of honeybee colonies were mainly by catching swarms and gifts from parents (Table 3). This indicate that there were no colony transportation from one place to other and beekeeper can access honeybee colony from their area. These are also opportunities for future honey production improvement in the study area were Presence of huge number of bee colonies.

Table 3: Beekeeping activities and potentials

Apiary site Inspection by Beekeepers

Participated respondents were interviewed to describe the frequency of inspecting their apiary and honeybee colonies. Majority of the beekeepers inspect their apiary and colonies everyday 70.2% of the respondents replied that they take a look externally into the hives every day, 28.8% per month and 1.0% per month (Table 4).

Table 4: Apiary site Inspection by Beekeepers

The trend of honeybee colony and products

Based on the majority of the respondents, the trend of honeybee colony and its Products were decreasing and some of the beekeepers also responded to honeybee colonies and yields were increasing and others responded to stable (Figure 2). As the result of data, most beekeepers faced with a shortage of food for their honey bee colony and faced with no products. Sometimes the colony population and there products were decreasing with various factors.

Figure 2: The trend of honeybee colony and products

Reasons for Decreasing the Trend of Cause of Honeybee Colony and Yield Decrease

The major cause of honey bee colony and yield decrease ranked by respondents were 1^st pets and predators, 2^nd Honeybee diseases and 3rd in appropriate agrochemical application (Table 5). All of these factors resulted in decrease in productivity and honeybee colony population. The result are agreement with [15,16] shortage of bee forage is ranked first due to population pressure, lack of land use policy and the high demand for farmlands put pressures on mountainous areas to be used for crop production and livestock grazing. These create deforestation, soil erosion and, irreversible ecological degradation. Shortage of bee forage directly associated with an off flowering period of major honeybee forages.

Table 5: Cause of honeybee colony and yield decrease

Similarly with [17] indicated that the presence of honeybee pests and pathogens, prevailing bad weather (prolonged precipitation and freezing and heavy wind speed), Lack of knowledge and skill of honeybee pest and diseases control, application of agrochemical (direct spray of pesticide on bee visited agricultural crops), shortage of bee forage, poor or absence of practice of hive shading, Lack of practice of hive inspection and shortage of improved hive types were ranked in the decreasing order of their importance.

The Prevalence of Honeybee Disease and Pests

In this study 52 beekeeping sites and 104 honeybee colonies were examined for major honeybee parasites (Varroa mites, bee lice, and tracheal mites), adult honeybee diseases (Nosema and Amoeba) and brood diseases (Chalk brood, American and European Foul brood) with their prevalence in the study area. However, the prevalence of AFB, EFB, SBD, and tracheal mite was not confirmed during the study period. Based on the data collection and laboratory diagnosis method during the study, the following results was recorded (Figure 3).

Figure 3: Field examination and laboratory diagnosis procedure and results.

Prevalence of Chalk Brood Disease

Out of 52 apiary sites 10(19.2%) and 104 examined colonies, 21(20.2%) were found infected with chalk brood disease (Ascosphaera apis). Highest prevalence was recorded in Wayu Tuka district (31.8%) and the lowest in Gobu Sayo district (10%) (Table 6).

Table 6: Prevalence of Chalk brood disease

The current result was lower than the previous reports conducted in different part of Ethiopia at different times. During the first time of its discovery in Ethiopia by [18], 61.5% of apiaries and 17.4% honeybee colonies were infected with the Ascosphaera apis. Afterward, the research conducted around Shoa and Arsi zones of Oromia region, about 56.5% was reported Desalegn [18]. The current result was less than result conducted at around Addis-Ababa also revealed about 43% prevalence Desalegn [19]. The diagnostic Chalk brood survey in all beekeeping potential regions of the country Aster et al., [20], 37.12%, 19.9% and 17.9% prevalence were reported for Amhara, Oromia and Benshangul-Gumuz regional states respectively.

The prevalence of Chalk brood disease was limited during the dry season. Similarly the growth of Chalk brood in the honey bee nest appears to be enhanced by high moisture (colonies not well ventilated in high humidity situations), cool temperatures, and colony stress and the humidity favors the multiplication of fungus [21-23].

Prevalence of Amoeba disease

For laboratory analysis 52 beekeeping sites were examined and M. mellificae was confirmed in apiary sites 24 (46.2%). The infectious level also tested that out of 104 honeybee colonies 52(50.0%) tested positive (Table 7). Overall colony level prevalence and infectious of amoeba disease was higher than in Wayu Tuka district and the infection of amoeba was higher in Diga districts.

Table 7: The Prevalence of Malpighamoebamellificae

N=Number of beekeeping sites and honeybee colonies examined, +Ve= Number of honey bee colonies found positive

The result showed that Malpighamoeba mellificae pathogen was occurred throughout the year. The same result reported by [24] indicated that Amoeba disease was reported to be widely distributed and identified in most places of the country throughout the year. The difference in prevalence and infestation level of amoeba disease was affected by agroecology and temperature. The result contradicted with the finding by [20,25], who reported that the highest cyst number (infestation) in the months of April and August (high humidity) and lowest intensity in the month of January (high temperature) was recorded.

Prevalence of Nosema Disease

For laboratory analysis 52 beekeeping sites and 104 honeybee colonies were examined. Nosema apis was confirmed in 26 apiary sites (50%) and 47 (45.2%) colonies during the honey active season dearth period respectively. The colony level prevalence also tested that out of 104 honeybee colonies 53(51.0%) tested positive in active season and 57(54.8%) tested positive in the death period (Table 8). The prevalence of Nosema disease in Diga district was higher in both active and dearth period. The difference of nosema disease may be due to the humidity condition. According to study by [26] the infestation level increase when bees are confined and transmit the pathogen among bees via the ingestion of contaminated comb material and water, and by trophallaxis; honey stores and crushed infected bees. Nosema can cause problems during winter months when bees are confined within the hive for long periods [27] (Figure 4).

Figure 4: Laboratory examination of Nosema apis and Malpighamoeba mellificae.

Table 8: Prevalence of Nosema apis in inspected apiaries and honeybee colonies.

N=Number of beekeeping sites and honeybee colonies examined, +Ve= Number of honey bee colonies found positive

Prevalence and Infestation of Varroa Mites

Varroa originally evolved in Asia, on a different species of honeybee, the Asian honey bee (Apiscerana), and has since spread to the western honey bee (Apismellifera) throughout most of the world. According to Varroa is now present in almost all honey bee colonies at different levels of infestation that are always increasing unless treated. From the total of 52 sample of apiary sites examined for the prevalence of varroa, 49 sites (94.2%) and similarly, from the total of 52 beekeeping sites examined in sealed brood, 48(92.3%) beekeeping site were Varroa mites positive. From the total of 104 honeybee colonies examined for infestation of Varroa mites in adult bees, 97 (93.3%) honeybee colonies were during the study period (Table 9).

Table 9: Prevalence and Infestation of Varro destructor

N=Number of apiary sites examined, +Ve= Number of sites found positive

The varroa destructor infestation was limited during the dearth period. The infestation was higher in the active period than in the dearth period. The difference in infestation in the active period may be due to more availability pollen source for brood rearing that related to egg laying of varroa in brood, as brood rearing depends on bee forage availability in the area and the result indicate that, the infestation rate was higher in the active period than in the dearth period.

The Prevalence and Infestation of Bee Lice

From the total 52 apiary sites examined for the prevalence of Braulacoeca, 12(23.1%) and from the total 104 honeybee colonies examined for infestation of Braulacoeca, 25(24.0%) honeybee colonies were infested (Table 10). The overall prevalence of bee lice (23.1%) observed in the current study was much greater than in other previous reports in Ethiopia. The present result was higher than the report of [28] who indicated the prevalence rate of 4% in adult honey bees. However, the current finding was less than the report by, who found a 42% lice prevalence in and around Holata. However, according to, the highest prevalence of bee lice observed in the strong colony than of the weak colony [29-34].

Table 10: The prevalence and infestation of bee lice.

N=Number of apiary sites examined, +Ve= Number of sites found positive

CONCLUSION AND RECOMMENDATIONS

Beekeeping is an important to rural communities by providing a variety of goods honey, wax, and pollen in particular and enriching the ecosystem by pollination. Based on the survey results, honeybee colony and its products decrease due to honeybee health, and lack of improved bee equipment, lack of bee forage, absconding and improper application of agrochemical. Based on laboratory results the most common parasites and pathogens such as Braulacoeca, Varroa destructor, Nosema apis, Malpighamoeba mellificae, and Ascosphaera apis were confirmed in areas. However honeybee diseases like AFB, EFB, Stone brood diseases and tracheal mites were not confirmed. Nosema apis and Ascosphaera apis were more prevent, and also varroa destructor was more prevalent and the amoeba disease was also more prevalent. To save honeybee colony form agrochemicals, beekeeper and others use chemicals which do not harm honey bees. Regular evaluation of honeybee disease and pest is needed to evaluate the health of honeybees to indicate the economic threshold of honeybee disease and pests.

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