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INFLUENCE OF WEATHER CONDITIONS ON HONEY BEE VISITS (Apis mellifera
carnica) DURING SUNFLOWER (Helianthus annuus L.) FLOWERING PERIOD
Z. Puškadija(1) , Edita Štefanić(1), A. Mijić(2), Z. Zdunić(2), Nada Paradžiković(1), T. Florijančić(1), A.
Opačak(1)
SUMMARY
The objective of the investigation was to determine influence of weather conditions to activity of honey bees
during flowering time of six sunflower hybrids. The investigation was carried out in 2002 growing season at
Kneževi Vinogradi located in Baranja county, north-eastern edge of Croatia. Honey bees communities were
moved to the field trial site inside Langstroth-Rooth's bee-hives. Honey bees visiting sunflower head
inflorescence was measured at 100, 200, and 300 meters by counting honey bees four times a day (9.00 am,
11.00 am, 1.00 pm, and 5.00 pm). The influence of weather conditions was analysed by Spearman correlation
coefficient. Results of the investigation show significant differences regarding honey-bee visit to the head
inflorescences in six hybrids, as well as significant influence of air temperature, humidity, precipitation,
minimum and maximum air temperature, and wind strength.
Key-words: honey bee, sunflower, visit, weather conditions
INTRODUCTION
Sunflower (Helianthus annuus L.) belongs to typical alogamic (cross pollinated) entomofilic plants,
which require pollinator’s effect high quality fertilisation. In general, the role of pollinators has been
well known since long ago but it has been quite neglected until recently. The importance of pollination
within the agricultural ecosystems, based on monoculture, crop rotation, and pesticide application, has
been neglected, so the pollinators have decreased or even disappeared over time.
(1) doc.dr.sc. Zlatko Puškadija, prof.dr.sc. Edita Štefanić, prof.dr.sc. Nada Parađiković, doc.dr.sc. Tihomir
Florijančić i prof.dr.sc. Anđelko Opačak - Sveučilište Josip Juraj Strossmayer u Osijeku, Poljoprivredni fakultet
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Osijek, Trg Svetog Trojstva 3, 31000 Osijek, Hrvatska, (2) dr.sc. Anto Mijić, dr.sc. Zvonimir Zdunić,
Poljoprivredni institut Osijek, Južno predgrađe 17, 31 000 Osijek, Hrvatska
These are some of the reasons for the experiments, , such as here presented, to deal with the activities
of honey bees in pollination of agricultural crops such as sunflower. Honey bees (Apis mellifera
carnica), because of their high numbers, intensive daily activity, as well as their body structure assure
pollen transportation from one sunflower head inflorescence to another. This provides for high quality
pollination of the tube shaped sunflower flowers (Free, 1993). Cimu (1960) noticed that sunflower
hybrids being pollinated by honey been produce up to 40% higher grain yield compared with those
which had not been pollinated by honey bees. Other authors (Kevan, 2001; Kumar et.al., 2002, 2003;
Pidek and Pohorecka, 2004) also confirmed such results and also emphasised the importance of
introduction of honey been pollination as a regular technologic measure in the cultivation of
sunflowers. Grain yield, besides oil content, is the most important component of oil yield (Mijić et al.,
2006.) what makes this trait highly attractive to farmers involved in the production of commercial
sunflower. Numerous investigations showed that there was a difference among sunflower hybrids
regarding their pollination by honey bees (Miklič 1992, Singh and Singh, 1999) caused by differences
in activity of bees in various weather conditions (Miklič, 1996; deGrandi-Hoffman et al., 2000). The
objective of this investigation was to determine the influence of weather conditions on honey bee visit
to sunflower head inflorescences.
MATERIAL AND METHODS
Investigation was carried out during 2002 growing season at Kneževi Vinogradi location, Baranja
County (nothern-east edge of Croatia). This area is characterised by moderate continental climate with
semiarid spots. Hydro meteorological data obtained from Brestovac-Belje station were used for
interpretation of meteorological conditions. Experimental material consisted of six sunflower hybrids
(Util, Lucil, PR64A42, PR63A90, Fakir, and Orion) widely used in Croatian agricultural production.
Honey bees communities were transported to the fields inside Langstroth-Rooth bee hives. Their
strength was appropriate to the corresponding strength for successful pollination (Free1993).
Honey bees visiting sunflower inflorescences were assessed at 100, 200, and 300 meters, by
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counting the individual bees present four times a day (9. 00 Am., 11. 00 Am., 1.00 pm., and 5.00
pm.). The weather conditions influence was measured by Spearman correlation coefficient.
RESULTS AND DISCUSSION
Total daily visit of the bees depended on weather conditions. The most frequent visit was noticed after
rainy days which occurred on the 4th and 7th of July 2002. During those days the daily average air
temperature was between 20 and 25 degrees centigrade whereas humidity varied between 65 and 75%
(Figure 1). This is in accordance with the investigations performed by Miklič (1996), Sihag and
Khatkar (1999), Patil and Viraktamath (2001), Nargis et.al. (2001), Mordago et. al. (2002), Kumar et.
al. (2002). These authors observed a decreased daily activity of honey bees on the days characterized
by maximum temperature and highest humidity. Different authors noticed the most intensive honey
bee activity during different weather conditions, depending upon particular investigation site and its
weather conditions. Kumar et al. (2002) pointed out agro-ecological data for Punjab county in India
showing the most intensive bee activity at 18.3 degrees centigrade and 60% humidity. Miklič (1996)
presents data obtained at Rimski Šančevi site near Novi Sad, Serbia, under weather conditions similar
to ours. Author observed the most intensive bee activity at 20 to 28 degrees centigrade and humidity at
40 to 50%. The results appear to be lower than those obtained in this investigation (65-75%).
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Figure 1. Influence of air temperature and humidity to honey bees visit of sunflower inflorescences during
flowering time
The lowest visit was estimated in the days interrupted by localized rainfalls (4th and 8th July 2002).
The total absence of honey bees was noticed on July 7th 2002 because of an all-day rain (Figure 2).
Honey bees do not exit bee hives during rainy days (Miklič 1996).
0
200
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1400
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1800
15 17 19 21 23 25 27 29
temperature (oC)
Num
ber
of
bees
Number of bees
-200
0
200
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600
800
1000
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1400
1600
1800
40 50 60 70 80 90 100
Humidity (%)
Num
ber
of
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Number of bees
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Figure 2. Precipitation influence to visit of honey bees to sunflower hybrids
Relationship between weather conditions and honey bee visit was analyzed by Spearman coefficient.
Table 1. show no significant correlation between honey bee visits and weather indicators. However,
positive correlation has been noticed between average and maximum daily temperature and the visits,
whereas higher humidity, heavy precipitation, stronger wind and lower daily temperature had negative
impact on sunflower inflorescence visits. Jocić et.al. (2000) made observations quite similar to this
investigation, i.e. the most intensive honey bee activities were noticed at daily temperature 20 to 28
degrees centigrade. Rain had strong negative impact on honey bee activity and pollination. Authors
also pointed out negative influence of minimum daily temperature on bee activity during the day if
lower than 10 degrees centigrade. The authors also suggest that the ideal ratio between minimum and
maximum daily temperature would be at 10 to 30 degrees centigrade. This has also been confirmed by
this investigation.
0
1
2
3
4
5
6
7
8
9
10
2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
July
mm Percipitation
0
200
400
600
800
1000
1200
1400
1600
1800
Num
ber
of
bees
Percipitation mm Number of bees
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Table 1. The relationship between weather conditions and honey bees visit of sunflower inflorescences
during flowering time
Weather indicator Spearman's correlation coefficient
Air temperature 0.420 NS
Humidity -0.252 NS
Precipitation -0.321 NS
Maximum air temperature 0.030 NS
Minimum air temperature -0.085 NS
Max/min air temp.(DTR) -0.030 NS
Wind -0.210 NS
Wind strength -0.114 NS
NS – non significant
CONCLUSION
Based on the above results it can be concluded that the weather conditions have evident influence on
sunflower inflorescence visit by honey bees. The most frequent visits were estimated at 20 to 25
degrees centigrade and humidity at 65-75%. Precipitation had negative impact to honey bees visit.
Statistical analysis showed strong positive correlation between average as well as maximum daily
temperature and the honey bee’s visits. Higher humidity, heavy rain fall, wind, and low temperature
had negative influence on sunflower inflorescences visits.
LITERATURE
1. Cirnu, I. (1960): Results of bee pollination of sunflowers. Apicultura 33(1): 18-20.
2. DeGrandi-Hoffman, Gloria, Watkins, J.C. (2000): The foraging activity of honey bee Apis Mellifera
and non-Apis bees on hybrid sunflowers (Helianthus annuus) and its influence on cross-pollination and
seed set. Journal of Apicultural Research 39 (1-2): 37-45.
3. Free, J.B. (1993): Insect Pollination of Crops, 2nd ed. Academic, London.
4. Kevan, P.G. (2001): Pollination: A Plinth, Pedestal, and Pillar for Terrestrial Productivity. The Why,
How, and Where of Pollination Protestion, conservation and Promotion. Entomological Society of
America Proceedings from Bees and Crop pollination-Crisis, Crossroads, Conservation: 7- 68.
5. Jocić, S. (2000): Stepen oplodnje kod hibrida suncokreta u 1999. godini. Naučni institut za ratarstvo i
povrtlarstvo, Novi Sad, Zbornik radova, Sveska 33: 81-90.
6. Kumar Manoj, Singh, R., Chand, H. (2002): Foraging activity of Apis cerana indica and Apis mellifera
visiting sunflower (Helianthus annuus L.). Shashpa, 9 (1): 31-34.
7. Kumar, Manoj, Singh, R. (2003): Pollination efficiency of Apis mellifera in seed production of
sunflower (Helianthus annuus L.). Journal of Entomological Research, 27 (2): 131-134.
8. Miklič, V. (1992):Utjecaj klimatskih činilaca i genotipa suncokretana posetu polinatora, Poljoprivredni
fakultet Univerziteta u Novom Sadu. Zbornik radova, 20:449-458.
9. Miklič, V. (1996): Utjecaj različitih genotipova i pojedinih klimatskih činilaca na posetu pčela i drugih
polinatora i oplodnju suncokreta, Magistarska teza. Poljoprivredni fakultet Novi Sad. Srbija.
10. Mijić, A., Krizmanić, Guberac, V., Marić, S. (2006.): Heritabilnost i međuzavisnost kvantitativnih
svojstava suncokreta (Helianthus annuus L.). Sjemenarstvo, 23 (4): 347-358.
11. Mordago, L.N., Carvalho, C.F., Souza, B., Santana, M.P. (2002): Fauna of bees (Hymenoptera:
Apoidea) on sunflower flowers, Helianthus annuus L., in Lavras-MG, Brazil. Ciencia e Agrotecnologia,
26 (6): 1167-1177.
12. Nargis, S., Srimathi, P., Krishnasamy, V. (2001): Influence of supplementary hand pollination on seed
yield in hybrid sunflower – KBSH 1. Madras Agricultural Yournal, 87 (7/9) 488-489.
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13. Patil, B.S., Shashidhar Viraktamath (2001): Foraging behavior of two species of honeybee on sesamum.
Karnataka Journal of Agricultural Sciences, 14 (3): 796-798.
14. Pidek, A., Pohorecka, K. (2004): Economical perspectives for beekeeping in ten countries accending to
the EU. Proceedings of the first European conference of Apidology, Udine, Italy. 16-17.
15. Sihag, R.C., Sunita Khatkar (1999): Foraging patern of three honeybee species on eight cultivars on
oilseed crops. 1. Diurnal foraging. International Journal of Tropical Agriculture, 17 (¼): 245-252.
16. Singh, L., Singh, N. (1999): Relative abundance of various insect visitors and foraging activity of Apis
mellifera L. on sunflower hybrid. Journal of Insect Science, 12 (2): 122-124.
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