Pol. J. Environ. Stud. Vol. 27, No. 2 (2018), 787-792
DOI: 10.15244/pjoes/74154
ONLINE PUBLICATION DATE: 2018-01-10
Original Research
The Impact of Selected Pesticides
on Honey Bees
Paweł Migdał1*, Adam Roman1, Ewa Popiela-Pleban1,
Monika Kowalska-Góralska2, Sebastian Opaliński1
Department of Environment, Hygiene and Animal Welfare, Wrocław University of Environmental and Life Sciences,
51-630 Wrocław, Poland
2
Institute of Biology, Wrocław University of Environmental and Life Sciences,
51-630 Wrocław, Poland
1
Received: 2 March 2017
Accepted: 28 May 2017
Abstract
The presence of honey bee in the environment has a significant impact on global agricultural
production. While searching for pollen and nectar, the bee is often exposed to several contaminants
such as plant protection products. The aim of this study was to assess the impact of selected pesticides
from various groups (fungicides, herbicides, insecticides) on the way the bees harvested food as well as
on their behavior, survival rate and the concentration of certain elements in the organisms of bee. The
concentration possibly similar to this applied in agriculture and recommended by the manufacturers,
were used. The research material was analyzed in terms of the presence of trace elements (manganese,
copper, iron, nickel, zinc, lead, cadmium) of different toxicity. The study clearly indicates that selected
pesticides used for the purpose of plant protection and plant cultivation may adversely on bees’ behavior
and accumulation of trace elements in their body. Among the tested pesticides particular attention should
be paid to fungicides that are not commonly tested for their effects on the honey organ. In own studies
showed, their effect significantly changed the content of copper and negatively affected the survival of the
bees.
Keywords: behavior, trace elements, pesticides, honey bee
Introduction
Intense development of agriculture and animal
production has caused exposure to substances with which
bees have never before come into contact. The increasing
demand for food has forced farmers to use more mineral
fertilizers and pesticides to generate higher yields [1]. The
*e-mail: pawel.migdal@upwr.edu.pl
residues of these substances in the form of contaminants
are then transferred into grains, vegetables, and fruit
[2]. They have also been discovered in herbs such as
mint (Mentha) or lemon balm (Melissa officinalis) [3].
While working on flowers, bees are exposed to direct
and indirect contact with pesticides which, depending on
the mode of action and the concentration of active
substance, can lead to sudden death of pollinating
insects or cause death within a couple of hours following exposure [4]. It becomes dangerous when the level
of pesticides or their residues in a beehive becomes
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high enough to adversely affect the functioning and
development of larvae [5]. This causes the bees to
become more susceptible to bacterial infections. This
is particularly risky in the case of American foulbrood
caused by Paenibacillus larvae.
Weakened bees and a disorganized colony become
more susceptible to this disease [6]. They also suffer
more frequently from nosemosis, also known as bee
dysentery, or varroosis [7]. Moreover, the microflora of
bee intestines is affected [8]. Some pesticides trigger
disorders of the digestive and endocrine systems, leading
to distention of the abdomen, as a result of which the
bees become slow and apathetic, showing difficulties
with active flying [9]. Bees are highly susceptible to
environmental changes and pollution, which is strongly
reflected in the significant decrease of their survival rate
[10].
The search for reasons for this phenomenon has
established a new disease entity called colony collapse
disorder (CCD). Several studies have indicated the
important role of pesticides in the appearance and
development of numerous pathological disorders in
bee organisms [11]. Although it is still hard to find one
cause of CCD, the significant impact of pesticides on its
development cannot be questioned. Animals and their
produce may also be used in the process of evaluating
the level of environmental pollution. Honey bees (A.
mellifera) serve as a bioindicator of contamination with
trace elements of toxic properties (copper, zinc, iron,
tin cadmium, lead, arsenic, and aluminum) [12]. Bees
constantly penetrate the environment seeking new
produce and the raw materials necessary to provide
for the functioning of their colony. Even though the
aforementioned elements may appear in pesticides
commonly used in agriculture, it is impossible to
determine unequivocally whether their presence in bees
and bee products originates in the environment or results
from the contact between bees and pesticides.
Selected manganese (Mn) negatively affects behavior and leads to disturbances in chitin synthesis,
while copper (Cu) is a natural component of the
hemolymph of bees [13-14]. Lead (Pb) and cadmium
(Cd) are very toxic for animals and the environment
[15]. Iron (Fe), nickel (Ni), and zinc (Zn) contaminants
in the honey bee body can occur because of botanical
origin, as well as anthropogenic factors around the
colonies [16]. The scientific literature indicates that
Pb, Cd, Cu, Mn, Ni, Zn, and Fe are the most important
heavy metals, and studies show a tendency for their
accumulation in living organisms [17-18]. Pesticides
that contain metals as active substances influence
the content of these elements in the organism of honey
bees.
The aim of this study was to assess the impact of
selected pesticides from various groups (fungicides,
herbicides, insecticides) on bee behavior, survival rate,
and the concentration of selected trace elements in their
organisms.
Migdał P., et al.
Material and Methods
Laboratory tests were carried out from June to midAugust. The studied material consisted of honey bee
workers (A. mellifera) of the Carniola race obtained from
one bee colony to each repeat [19]. Ten-day-old worker
bees were distributed into seven dietary treatments. They
were transported to the laboratory where the container
was left for 30 min (at about 26ºC). The bees were then
rendered unconscious by exposure to ammonium nitrate.
After about 30 seconds, the insects became unconscious
for about 2-3 min, when they were moved to experimental
cages at 160 individuals per cage. The cages were supplied
with lids, each with two holes with 5 cm3 food dispensers
containing test or control solutions. Bees were placed
in identical cages of wood and glass with dimensions of
50 × 150 × 150 mm. Inside each cage were placed frames
with wax foundations (size approximately 120 × 120 mm)
[20]. The cages were put in an incubator where constant
temperature and humidity (the first 24 hours of experience
T 35°C, subsequently 27ºC, H 75%) were maintained [21].
Throughout the study, bees were fed with 2 mol/dm3
sugar syrup. The first 24 h were dedicated to adjusting
to the new environmental conditions, feeding, and then
– after removal of dead individuals – starting the actual
experiment.
Each dietary treatment was divided into six
replicates. Pesticides were selected in the manner
allowing for double representation of each group (two
kinds of insecticides, two herbicides, and two fungicides). The concentration of each pesticide was in
accordance with the recommendation of the manufacturer.
Each dose of pesticide was dissolved in 100 cm3 of sugar
syrup (2 moll /dm3). Experimental groups were:
–– Group K: control, pesticide-free sugar syrup.
–– Group A: Miedzian 50WP (fungicide 1) with active
substance of copper oxychloride- authorized for trade
and distribution until 2019, dose 0.35 g/100 cm3 of
syrup.
–– Group B: thiram granuflo 80WG (fungicide 2) main
active ingredient thiram, authorized for use until
2020, dose 0.60 g/100 cm3 of syrup.
–– Group C: Fastac 100EC (insecticide1) active substance
α-cyphermetrin, authorized for distribution until
2020, dose 0.04 cm3/100 cm3 of syrup.
–– Group D: Actara 25WG (insecticide 2) active
substance thiamethoxam, authorized for trade until
2021, dose 0.04 g/100 cm3 of syrup.
–– Group E: Basagran 480SL (herbicide 1) active
substance bentazone, authorized for distribution until
2020, dose 1.2 cm3/100 cm3 of syrup.
–– Group F: Metafol 700SC (herbicide 2) active substance
metamitron, authorized for production until 2016,
dose 0.60 cm3/100 cm3 of syrup.
Every day the solutions in food dispensers were
replaced with new ones in order to minimize the risk
of chemical changes in the tested substances. Dead
individuals were collected and stored in a freezer
(-20ºC). After completion of the experiment the samples
The Impact of Selected Pesticides...
were defrosted and triturated using a ceramic crucible.
Afterward the samples were transferred quantitatively to
a petri dish and placed in a dryer laboratory for 8 h at
45ºC. In order to obtain precisely dried and homogenized
samples, dried material was triturated and placed on
RADWAG WPX 50S moisture balances, where it was
dried to a constant weight at the same temperature as
in the incubator. Each sample was weighed at 1 g (to
the nearest 0.10 mg) and samples of biological material
were weighed in Teflon dishes using a RADWAG WAS
220/X analytical balance. The samples were covered with
5 cm3 of spectrally pure 69% nitric acid (TRACEPUR
EMD Millipore Corporation). These sample preparations
were mineralized in ANTON PAAR MULTIWAVE 3000
microwave digestion for 30 minutes. The whole process
lasted two hours.
After mineralization the obtained mineralisates
were centrifuged and the content was moved into
new Falcon tubes. The resulting mineralisates were
analyzed quantitatively using flame atomic absorption
spectrophotometry (AAS). Elements to which bees might
be exposed in the natural environment and elements that
appeared in the chemical structure of active substances
of the pesticides were indicated. The indicated trace
elements included Cu, Mn, Fe, Ni, Cd, Pb, and Zn.
Moreover, behavioral observation was carried out
during the study. The results obtained in experimental
groups were related to a control group. The following
behavioral factors were taken into account: aggression,
walking, grooming, reversal, immobility, and attempts to
reconstruct comb foundations. If no irregularities were
noticed during observation it was marked with ‘-’ in the
table, whereas any behavioral changes or dysfunctions
were marked with a ‘+’ (small), ‘++’ (medium), or ‘+++’
(big). An assessment was made based on frequency
of given behavior. Observations were carried out in
15-min periods for each group by two observers. The
results obtained were analyzed statistically using
Statistica for Windows v. 10.0. The mean, standard
deviation, and relevance of differences between given
groups were established. Statistical analysis was made
based on Duncan test (P
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