The purpose of our experiment was to establish how exposure to a constant magnetic field of 98 mT affects behavior in terms of viability and larval mass of the old house borer (Hylotrupes bajulus L.). It is demonstrated that larvae exposed to this magnetic field show statistically significant higher viability, as well as a tendency of mass increase in comparison with the control group. These results can be attributed to the modulatory effect of the employed external magnetic field on metabolism and neurohumoral regulation in the insects.Cilj našeg eksperimenta je bio da se utvrdi kako izlaganje konstantnom magnetnom polju od 98 mT utiče na ponašanje u smislu preživljavanja i mase larvi kućne strižibube (Hylotrupes bajulus L.). Pokazano je da larve koje su se nalazile u magnetnom polju pomenutih karakteristika imaju statistički značajno veće preživljavanje, kao i tendenciju povećanja mase u odnosu na kontrolnu grupu jedinki. Ovi rezultati se mogu pripisati modulatornom uticaju spoljašnjeg magnetnog polja na metabolizam i neurohumoralnu regulaciju insekata.Projekat ministarstva br. 14302

Prolić, Z.

Rauš, Snežana

Todorović, Dajana

Digital Repository of Archived Publications - Institute for Biological Research Sinisa Stankovic (RADaR)

INTRODUCTION
From its very beginnings, life has been exposed to 
the impact of the Earth’s magnetic field (EMF), in 
whose presence the phylogeny of organisms took 
place. Technological development, especially since 
the middle of the 20th century, brought with it a 
host of devices that have wide applications and emit 
additional electromagnetic radiation into the envi-
ronment. This increases the need for research on the 
biological effects of individual components of the 
given ecophysiological factor. 
In the past few decades, it became completely 
clear that biological systems are sensitive to even 
very weak external magnetic fields (Adey, 1981; 
Gould, 1984; Cain et al., 1987). A series of investi-
gations has in several recent years been devoted to 
the impact of magnetic fields (MF) on biological 
systems, both at the level of atoms and molecules, 
and at higher levels of biological organization. One 
of the organisms that lent itself as suitable for test-
ing the impact of constant magnetic fields (CMF) 
on life functions is the old house borer Hylotrupes 
bajulus L. Larvae of this species are one of the most 
severe pests in coniferous forests. They are mostly 
found on pine, fir, and spruce trees, feeding on tree 
mass. They can also be found in infected lumber in 
stored material, beams, wooden stairs, and floors 
(Kovačević, 1956). This species does not accept the 
standard substrate for laboratory rearing of some 
species of the family Cerambycidae, so the test we 
applied is essentially a test of their viability under 
conditions of starvation.
The purpose of the present work was to establish 
the impact of a constant 98-mT magnetic field on 
behavior of the old house borer Hylotrupes bajulus 
in terms of viability and change in larval mass. Such 
research should shed light on the effects of an omni-
present ecophysiological factor on the biology and 
abundance of this species.  
MATERIALS AND METHODS
The adult body of H. bajulus (Fig. 1) is 8 to 20 mm 
long, brown in color, and covered with tiny gray 
hairs, which are longer at the neck shield and legs. 
At the neck shield there are two naked shiny bulges. 
Two white narrow stripes run across the elytra. 
Adults emerge in summer. The females lay eggs in 
splits or cracks of a tree, in groups of 50 to 150. After 
2 to 3 weeks, the larvae hatch and immediately pen-
etrate the tree’s wood.
Larvae of the old house borer Hylotrupes bajulus 
VIABILITY OF OLD HOUSE BORER (Hylotrupes bajulus) LARVAE EXPOSED TO
A CONSTANT MAGNETIC FIELD OF 98 MT UNDER LABORATORY CONDITIONS
SNEžANA RAUš, DAjANA TODOROvIć, and Z. PROLIć
Laboratory of Magnetobiology and Behavior, Siniša Stanković Institute for Biological Research, 11060 Belgrade, Serbia
Abstract — The purpose of our experiment was to establish how exposure to a constant magnetic field of 98 mT affects 
behavior in terms of viability and larval mass of the old house borer (Hylotrupes bajulus L.). It is demonstrated that lar-
vae exposed to this magnetic field show statistically significant higher viability, as well as a tendency of mass increase in 
comparison with the control group. These results can be attributed to the modulatory effect of the employed external 
magnetic field on metabolism and neurohumoral regulation in the insects.
Key words: Magnetic field, viability, development, Hylotrupes bajulus
UDC 595.768.1:591.1:591.5 
129
Arch. Biol. Sci., Belgrade, 61 (1), 129-134, 2009                  DOI:10.2298/ABS0901129R
S. RAUš ET AL.130
L. were used in the experiment. The larvae have a 
pale yellow color and stunted extremities. They move    
with the aid of seven abdominal nipples and bulges 
on their bodies. Adult larvae are ca. 30 mm long. 
Larval development may last 3 to 4 years, but also 
several decades, depending on the physiological state 
of the tree, primarily temperature and humidity.
Larvae (N = 20) taken from fir tree lumber (a 
roof beam) originating from Mt. Tara, Western 
Serbia, were removed to laboratory conditions: 
temperature of 23 ± 1°C, relative humidity of 78 ± 
10 %, and light regime of 12 h day/12 h night. Light 
intensity was around 100 lx. 
The initial larval mass was on average 95 to 135 
mg per larva. The larvae were randomly divided 
into two groups of 10 larvae each. They were then 
placed individually in glass Petri dishes (50 mm in 
diameter and 22 mm in height) filled with nutrient 
substrate. The nutrient substrate was a mixture of 
water, sugar, cornmeal, agar, and a mass chips of 
the same tree, cooked for 6 to 8 minutes and cooled 
to room temperature. The larvae spent 24 h on this 
substrate for feeding control, i.e., to test substrate 
acceptance. It was established that only 40% of lar-
vae in each group consumed the substrate offered in 
minimal amounts. 
A magnetic field was formed by a pair of per-
manent horseshoe magnets forming a relatively 
homogeneous constant magnetic field within their 
poles (Fig. 2). The distance between the poles was 
68 mm, and the average value of the magnetic field 
in this space was 98.29 ± 11.75 mT. Magnetic induc-
tion in the space where the larvae were placed was 
measured with a GM05 magnetometer from Hirst 
Magnetic Instruments Ltd., probe PT 2837.
The experimental group of 10 individuals in 
Petri dishes was placed in the magnetic field, while 
the control group of 10 individuals in Petri dishes 
was placed at a distance where the magnetic field was 
at the level of EMF. The larval mass was measured 
every 10th day while the larvae were alive (130 days 
in the control group, 160 days in the CMF group). 
The results obtained from these measurements were 
compared by the Student t-test (for two independ-
ent groups). Larval viability was also monitored and 
analyzed by the Z-test.
RESULTS
It can be seen in Figs. 3 and 4 that the group exposed 
to a CMF of 98 mT showed better viability, which 
resulted in an increase of the total average mass 
and life span. In the control group, larval mass 
Fig. 1. Adult of old house borer H. bajulus.
VIABILITY OF Hylotrupes bajulus LARVAE EXPOSED TO A CONSTANT MAGNETIC FIELD 131
stagnated until day 80. After this, the average lar-
val mass decreased until the last individual in the 
group died. Average larval mass in the CMF group 
showed a trend of slight increase until day 90, after 
which it started to decrease, which was especially 
expressed after day 110. Comparison of larval mass 
changes revealed no statistically significant differ-
ences between the control group and larvae exposed 
to the CMF.
In contrast to body mass, the results obtained 
on larval viability showed statistically significant 
differences between the control and treated groups 
on days 50 (Z = 3.162, p < 0.01), 60 (Z = 2.190, p < 
0.05), 110 (Z = 1.989, p < 0.05), and 120 (Z = 2.760, 
p < 0.01), higher viability being found in the group 
exposed to a CMF of 98 mT (Fig. 4). The last larvae 
in the MF die as late as 30 days after death of the last 
larva in control, i.e., they live for 160 days.
DISCUSSION
The results indicate that H. bajulus larvae show sta-
tistically significant higher viability when exposed 
to a CMF of 98 mT. It was also observed that the 
last larvae exposed to the CMF die as late 30 days 
after death of the last larva in the control. In addi-
tion to this, the individual mass of larvae exposed 
to the CMF increased until day 90, but without 
statistically significant differences compared to the 
control. After this period, a decrease of mass was 
observed, but that change was slower than in the 
control group.
There is much evidence indicating that a mag-
netic field affects the development and viability of 
various insects. In Drosophila melanogaster, after 
exposure to a CMF of 130 mT to 180 mT, changes 
in genetic material were observed within viability 
categories through three consecutive generations 
(Prolić and Anđelković, 1992). A constant mag-
netic field of 375 mT stimulates development of 
workers in the pupal stage (Prolić and jovanović, 
1986). Similar results were obtained by Prolić and 
Nenadović (1995), who found that development of 
Tenebrio molitor was affected by a magnetic field of 
similar characteristics (320 mT), metamorphosis of 
pupae into adults being 14% faster in the presence 
of the magnetic field. On the other hand, the meta-
morphosis of pupae of the housefly Musca domestica 
exposed to an extremely low-frequency magnetic 
field (50 Hz, 6 mT) was significantly slowed at tem-
peratures of 19 and 24°C. The life span of an adult in 
a magnetic field with these characteristics is signifi-
cantly extended at a temperature of 24°C compared 
Fig. 2. Magnetic field exposure system. 1 – relatively homogenous magnetic field with average mag-
netic induction of 98 mT where samples are placed; 2 – inhomogenous magnetic field.
S. RAUš ET AL.132
Fig. 3. Influence of a constant magnetic field (98 mT) on larval mass.
Fig. 4. Influence of a constant magnetic field (98 mT) on larval viability. *p < 0.05 and **p < 0.01 indicate 
significant differences compared to the control (Z test).
VIABILITY OF Hylotrupes bajulus LARVAE EXPOSED TO A CONSTANT MAGNETIC FIELD 133
to the control (Stanojević et al., 2005).
viability of phytophagous insects, to which cat-
egory H. bajulus belongs, depends on a number of 
abiotic factors, such as temperature, humidity, and 
interaction of temperature and nitrogen content in 
food (Lindroth et al., 1997; Ivanović and Nenadović, 
1999); plant protein quality (Broadway and Duffey, 
1988; Felton et al., 1989); and the balance of amino 
acids in proteins. Starving or inadequate food affects 
the physiology of all cells in various ways via 
fine molecular mechanisms, disrupting the dynam-
ic equilibrium of basic biological processes. The 
response of insects during development on inad-
equate food is very similar to their response to 
unfavorable temperatures (slowing of development, 
delay of metamorphosis due to numerous moltings). 
The response of insects to unfavorable temperature 
and food is associated with reaction at the level of 
the endocrine system, i.e., hormones that control 
development. Absence of food in Bombyx mori 
slows larval development (Panov, 1966). Inadequate 
substrate in some Galleria mellonella larvae at the 
initial stages inhibits metamorphosis, whereas other 
larvae of this species molt several times (Bogus and 
Wolbert, 1987). In gypsy moths reared from egg to 
imago on locust leaves (which have lower protein 
and free sugar contents than oak leaves, but con-
tain more tannin, flavonoids, and alkaloids), larval 
development is extended, with significant increase 
in the activity and number of different types of 
neurosecretory neurons of the medial group (Perić-
Mataruga, 1997). One possible way of explaining our 
present results is to postulate a modulatory effect of 
hormones released from neurosecretory neurons of 
H. bajulus brain ganglions.
It has already been shown that a CMF with aver-
age induction of 320 mT affects cytological charac-
teristics and activity of protocerebral mediodorsal A2 
neurosecretary neurons in Tenebrio molitor (Perić-
Mataruga et al., 2006). Upon exposure of T. molitor 
pupae to this magnetic field, a significant increase 
in A2 neurosecretory neurons and their nucleoli 
was observed, which indicates intensive synthesis of 
neurosecretory material. Neurohormones released 
from these cells are involved in regulation of metab-
olism and can influence the concentrations of pro-
teins, lipids, and sugars, as well as overall metabo-
lism, and consequently affect viability. In addition, 
an extremely low-frequency magnetic field (50 Hz, 
20 mT average induction) also changes the activity 
of medial protocerebral neurosecretory neurons and 
corpora allata in Cerambyx cerdo larvae. In these 
larvae, after 30 days of exposure, such a magnetic 
field causes a decrease of neurosecretory A1 and A2 
neuron activity, while the activity of corpora allata is 
increased (Nenadović et al., 2005).
Initial increase in larval mass of H. bajulus 
reared on a protein-rich substrate and exposed to a 
98-mT CMF could be attributable to the field’s effect 
on metabolism. It has already been shown that when 
the cerambycid beetle Morimus funereus is reared on 
an artificial diet much richer in proteins than tree 
mass, protein metabolism is activated and proteo-
lytic activity is increased, as in body mass (Ivanović 
and Nenadović, 1999). In H. bajulus (which belongs 
to the same family), this mechanism is not applica-
ble, given that, according to our results, larvae of this 
species only moderately accept the substrate. Thus, a 
possible explanation of our results could be that the 
MF exerts direct or indirect (via octopamine neuro-
hormone) influence on carbohydrate metabolism. 
Further research is needed to confirm this.
We can conclude that the applied MF, whose 
intensity is many (> 4000) times higher than that 
of the Earth’s magnetic field (to which the insects 
are constantly exposed), can be considered to be a 
stressogenic factor. The effects observed in terms 
of viability and larval mass of H. bajulus could be 
attributable to changes at the level of the neuroendo-
crine system and metabolism. However, to confirm 
this hypothesis, additional research is needed, which 
might also yield a histological explanation of possi-
ble mechanisms governing external MF influences.
Acknowledgment — This work was supported by the Ministry of 
Science of the Republic of Serbia (Grant 143027).
REFERENCES
Adey, W. R. (1981). Tissue interactions with nonionizing elec-
tromagnetic fields. Physiol. Rev. 61 (2), 435-514. 
Bogus, M. I., and P. Wolbert (1987). Diet influences Galleria 
mellonella development and sensitivity to juvenilizing 
S. RAUš ET AL.134
treatments. Zool. Jahrb. Abt. Allg. Zool. Physiol. Tiere 91 
(2), 211-220.
Broasway, R. M., and S. S. Duffey (1988). The effect of plant 
protein quality on insect digestive physiology and the 
toxicity of plant proteinase inhibitors. J. Insect Physiol. 
34, 1111-1117.
Cain, C. D., Adey, W. R., and R. A. Luben (1987). Evidence that 
pulsed electromagnetic fields inhibit coupling of ade-
nylate cyclase by parathyroid hormone in bone cells. J. 
Bone Miner. Res. 2(5), 437-441.
Felton, G. W., Broadway, R. M., and S. S. Duffey (1989). 
Inactivation of protease inhibitor activity by plant-
derived quinones: complications for host-plant resist-
ance against noctuid herbivores. J. Insect Physiol. 35, 
981-990.
Gould, J. L. (1984). Magnetic field sensitivity in animals. Annu. 
Rev. Physiol. 46, 585-598. 
Ivanović, J., and V. Nenadović (1999). Uticaj hrane i tempera-
ture na životni ciklus fitofagnih insekata. Pesticidi 14, 
309-328.
Kovačević, Ž. (1956). Primijenjena entomologija. III. Šumski 
štetnici. Poljoprivredni nakladni zavod, Zagreb. 
Lindroth, R. L., Klein, K. A., Hemming, J. D. C., and A. M. Feuker 
(1997). variation in temperature and dietary nitrogen      
affect performance of the gypsy moth, Lymantria dispar 
L. Physiol. Entomol. 22 (1), 55-64.
Nenadović, V., Mrdaković, M., Lazarević, J., Mirčić, D., Todorović, 
D., and Z. Prolić (2005). Temperature and magnetic field 
effects on the activity of protocerebral neurosecretory 
neurons and corpora allata in Cerambyx cerdo L. larvae. 
Arch. Biol. Sci. (Belgrade) 57 (1), 19-24.
Panov, A. A. (1966). Neurosecretory cells in the brain of silk-
worm and their reaction to starvation. Dokl. Akad. Nauk 
SSSR 170 (4), 952-955.
Perić-Mataruga, V. (1997). Activity of Enzymes of the Antioxidative 
System and That of Protocerebral Neurosecretory Cells 
in Lymantria dispar L. Caterpillars from Different 
Populations under Conditions of Nutritional Stress. 
Doctoral Dissertation, Faculty of Biology, University of 
Belgrade, Belgrade.
Perić-Mataruga, V., Prolić, Z., Nenadović, V., Mrdaković, M., and 
M. Vlahović (2006). Protocerebral mediodorsal A2’ neu-
rosecretory neurons in late pupae of yellow mealworm 
(Tenebrio molitor) after exposure to a static magnetic 
field. Electromagn. Biol. Med. 25, 127-133.
Prolić, Z., and V. Nenadović (1995). The influence of a perma-
nent magnetic field on the process of adult emergence in 
Tenebrio molitor. J. Insect Physiol. 41, 1113-1118. 
Prolić, Z., and Z. Jovanović (1986). Influence of a magnetic field 
on the rate of development of the honeybee preadult 
stage. Period. Biol. 88, 187-188.
Prolić, Z., and M. Andjelković (1992). The effect of a strong 
magnetic field on the frequency of genetic loads in 
Drosophila melanogaster. Acta Vet. 42, 343-350.
Stanojević, V., Prolić, Z., Savić, T., Todorović, D., and B. Janać 
(2005). Effects of an extremely low-frequency (50-Hz) 
magnetic field on development dynamics of the house-
fly (Musca domestica L.). Electromagn. Biol. Med. 24(2), 
99-107.
ПРЕЖИВЉАВАЊЕ ЛАРВИ КУЋНЕ СТРИЖИБУБЕ HYLOTRUPES BAjULUS ИЗЛОЖЕНИХ 
КОНСТАНТНОМ МАГНЕТНОМ ПОЉУ ОД 98 MT У ЛАБОРАТОРИЈСКИМ УСЛОВИМА
Снежана Рауш, Дајана ТоДоРовић и З. ПРолић
Лабораторија за магнетобиологију и понашање, Институт за биолошка истраживања “Синиша Станковић”, 
11060 Београд, Србија
Циљ на­шег екс­перимента­ је био да­ с­е утврди 
ка­ко из­ла­га­ње конс­та­нтном ма­гнетном пољу од 
98 mT утиче на­ пона­ша­ње у с­мис­лу преживља­­
ва­ња­ и ма­с­е ла­рви кућ­не с­трижибубе (Hylo­tru­pes 
ba­ju­lu­s L.). Пока­з­а­но је да­ ла­рве које с­у с­е на­ла­з­и­
ле у ма­гнетном пољу поменутих ка­ра­ктерис­тика­ 
има­ју с­та­тис­тички з­на­ча­јно већ­е преживља­ва­ње, 
ка­о и тенденцију повећ­а­ња­ ма­с­е у однос­у на­ 
контролну групу јединки. Ови рез­улта­ти с­е могу 
припис­а­ти модула­торном утица­ју с­поља­шњег 
ма­гнетног поља­ на­ мета­болиз­а­м и неурохумора­л­
ну регула­цију инс­ека­та­.


Viability of old house borer (Hylotrupes bajulus) larvae exposed to a constant magnetic field of 98 mT under laboratory conditions

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Viability of old house borer (Hylotrupes bajulus) larvae exposed to a constant magnetic field of 98 mT under laboratory conditions

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