The Effect of Pollen Supplementary Feeding on the Production of Honeybee (Apis mellifera) During Dearth Periods Under Haro Sabu Condition of Kellem Wollega Zone, Western Ethiopia

To have the required colony population, feeding the colony is very crucial when there is a shortage of bee flora in the environment. The aim of this study is, therefore, to test the effect of pollen supplementary feeding during dearth period (2015/16 to 2016/17) at apiary site of Haro Sabu Agricultural Research Center of Kellem Wollega Zone, Western Ethiopia. Three treatments namely: Chick pea (Cicer arietinum), Mung bean (Vigna radiata) and Soybean (Glycine max) each with four replication by Completely Randomized Design was used. From the result, all the fed types consumed by the bee colonies and they were more consumed during dry season than rainy. Statistically, there was no significant difference (p>0.05) observed between the given fed group. From the internal data recorded, the colonies which fed different supplementary pulse flour invests more than the unfed group. Therefore, it can be concluded that, giving pollen supplementary feeding at the time of dearth period maintains the strength of bee colony within the hive and attain to the next natural pollen and nectar flow season.

Feeding of different pollen substitute was done externally to provide bees' easy to collect as did for natural pollen. According to Safari et al. (2010) honey bees by nature need to buzz to collect powdery substances which is an easy method and consumes minimum time and labor. The time of providing supplementary feeding was done from February to March and July to August which are the time of dearth periods in the study area. Supplementary feeding was suspended when diets flour consumption stopped by honey bees because of the availability of natural pollen (Mattila and Ottis, 2006). The pollen and brood area in the colonies were recorded for every 21 days interval with the help of measuring frame (wire grid) consisting of squares, each of one inch 2 (Sena, et al, 2012. The values thus obtained was converted in to cm 2 by multiplying with a factor of 6.45. Total bee strength was measured in terms of frames actually covered by bees (Keller, et al, 2005). Bee strength of all the experimental colonies was recorded at an interval of 21 days which is the developmental period of worker honey bees. For all treatments seasonal colony management was applied. The preparation of different flour is that, it was roasted and the skin of different flour come out and powdered to the texture and consistency to be accepted by honey bees and water was added to the weighted powder until it turns to soften texture (Tolera Kumsa, 2014). SAS version 9.1.3 (SAS Institute, 2003) computer package was used for analyzing all the data. Means and standard deviations of the recorded data were calculated using SAS Software (SAS Inc., 2003). Determination of the significant differences between honey samples was done using one-way ANOVA. Consumption rate, number of frame with bees, pollen, brood, nectar and honey area in cm 2 on frame were used for mean separation.

Consumption rate of feeding
The mean consumption rate of each feeding types that were applied during dry season are indicated in Figure 1. The utilization rate (gram/colony) of each feed type was found slightly in ascending for each consecutive days during dry season (March). From the feed types, Mung bean found more preferred by a colony with a mean of 208.722 gram per colony while Soya bean was the less consumed with a mean of 191.406 gram per colony during dry season (Figure 1). At the time of rainy season, the consumption rate of each diet by colonies was increased during the first to fourth days while decreased on the fifth days.
From Figure 2, it can be observed that the maximum and minimum flour rate of the given diet was consumed by mung bean (28.5gram/colony) and chickpea (13.98gram/colony) respectively during rainy season (July to August). Honey bees prefer diets that return the proper ratio of nutrients necessary for optimal survival and homeostasis by evaluating the nutritional composition of the feeds provided to them (Corby-Hurris et al.,2018) The present study showed that bee colonies utilized more of the given feed type at the period of dry season than rainy season of the study area. This might be during rainy season the bee foragers are not active due to chilling. According to investigation by Riessberger and Crailsheim (1997), on sunny days foragers were too busy with almost no periods of inactivity while due to a lack of light they prevented from flight. Tolera Kumsa (2014) proved that high daily consumption of pea flour is 348.9 and 128 gram per colony in dry and rainy season respectively, and honeybees stored enough flour in combs for further consumption.

Number of frame with bees
The average number of frame with bees are indicated in Table 1. Statistically no significant (p > 0.05) variation between feed types was observed except colonies without supplementary feeding. The highest frame with bees was counted by mung bean (6.66) as compared with the least which is unfed (3.28) colony. This study is less than the result by Tolera Kumsa (2014), who recorded an overall average of 9.7±2.6 frames of bees fed on pea flour. Kumer and Agrawal (2013) reported that number of bee covered on frames are positively affected by feeding protein-rich diet to bees.

Brood and pollen area on frame (cm 2 )
No statistically significant difference (p>0.05) was observed between the supplementary feeds given on brood area on frame (cm 2 ) during dearth period of the study area. The maximum mean of brood area on frame was recorded by soybean (740 cm 2 ) whereas the unfed colony produces (275 cm 2 ) from a natural pollen. The present study result is less than the finding of Tolera Kumsa (2014) who recorded 1274.3 cm 2 ±195 cm 2 after feeding a colony with pea flour in dearth period. The variation occurred might be due to the difference in nutritional composition of the feed, bee strength and the environment of the apiary site. Prakash, et al. ( 2007) have indicated that when there is unavailability of pollen and nectar around the apiary area, supplementing artificial pollen maintain the colony strength throughout dearth period and help the colony improve brood strength. Al-Gamdi (2002) ; Dastouri et al. (2007) and Abusabbah et al. (2012) have obtained from feeding of soybean flour singly or in combination with other flour indicate its high potential for improving colony maintenance and build brood production during a shortage of natural pollen.
Different feed types were analyzed after feeding the colonies for pollen storage on the comb and recorded on the 21 st days of feeding. From the result (Table 1), no significant difference (p>0.05) was recorded between diet types. soybean fed colonies stored more pollen (236.9 cm 2 ) as compared with unfed colonies (83.7 cm 2 ). The percentage of protein content was high by soya bean (35-52) which is followed by mung bean (27.2) and chick pea (22.7), ( Vollmann, 2016). Pea, chickpea and soybean flour are relatively contain high protein and locally easily available as compared to other bee feeding materials and preferred as pollen supplements (Somerville, 2005).

Nectar and honey area on frame (cm 2 )
The average nectar and honey area on frame were indicated in Table 1. The highest nectar (1396.9 cm 2 ) and honey (2096.9 cm 2 ) was found on the frame which fed the soybean flour while unfed colonies collects a smaller amount of nectar (170.3 cm 2 ) and honey (349.2 cm 2 ). From this study, a direct proportional result was observed on the number of frame with bees, brood, pollen, nectar and honey area in cm 2 on 21 st days on application supplementary feeding.
According to the experimental result by Tolera Kumsa (2014), pea flour experimental group have good influence on dearth period brood production, colony population and honey production. Somerville and Collins (2007) have suggested that colonies maintained with pollen supplements in dearth periods would be in a better position to develop early brood production, accumulate nectar and stored surplus honey.

Conclusion
From the present study, colonies consumed all types of fed, even though their rate varies. Relatively, Mung bean flour was more consumed, and the fed colony inspired more during dry season than rainy season. Based on the result it can be concluded that, Soybean flour supplement produced more internal resources like colony population, brood, pollen and honey production although its consumption was less than Mung bean. Therefore, it can be concluded that, giving pollen supplementary feeding at the time of dearth period maintains the strength of bee colony within the hive and attain to the next natural pollen and nectar flow season.