Biol. Cybernetics 26, 41--44 (1977) Biological Cybernetics �9 by Springer-Verlag 1977'

Communication between Termites by Biofields*

G. Becker Bundesanstalt f(ir Materialpriifung Berlin-Dahlem

Abstract . Building of vertical galleries ("runways") by termites of the species Heterotermes indicola (Was- mann) is suppressed in the interior area of arrange- ments of plastic containers with equal groups of termites and takes place preferably at the periphery. This reaction is not induced by chemical, vibrational or thermal influences. Shielding separation by plates of glass, plastic foam or various metals demonstrated, that the influence on activity and directional behaviour is caused by fields produced by the termites. They are most probably alternating electric fields. These bio- fields act together or, if the direction of the gradients differs, in competition with a weak alternating mag- netic field in the air-conditioned experimental room. The centrifugal reaction of the termites to the bio- fields which do not influence the feeding activity, induces gallery building at the periphery of the nesting area.

-~27~ and ---80% rel. humidity in the dark. The containers were covered with black textiles or carton boxes in most of the series. After some days the termites start building vertical galleries ("runways") of vermiculite particles at the edges of the container (Fig. 1). The position and the length of the galleries were measured at 24 h intervals and the galleries were removed daily.

Horizontal galleries of termites can follow the main directions of the geomagnetic field (Becker, 1971). Compensation or turning of the magnetic field in a Helmholtz-coil leads to disorientation or to following

Observations on the behaviour of termites, mainly with respect to their gallery building (Becker, 1972), led to the assumption, that colonies in different glass or plastic containers may react to physical field in- fluences produced by neighbouring groups. Tests showed, that this is really the case.

For these tests groups of about 500 workers and larvae with some soldiers (0.66 g) of Heterotermes indicola (Wasmann) were kept in polystyrene-con- tainers of 3.5 cm x 5.5 c m x 9.5 cm (height) with a number of small holes in the lid in a substrate of expanded and screened vermiculite (about 2 cm high) with a moisture content of 300 % and a piece of wood in the vermiculite (Fig. 1). The characteristics of the wood blocks were equal in all parallels. The colonies were kept in an air-conditioned basement room at

* This paper was presented at the International Congress of Entomology in Washington (D.C.), USA, on August 23, 1976. - - Experiments with support by the Deutsche Forschungsgemeinschaft

Fig. 1. Polystyrene-container with vermiculite as substrate and galleries built by Heterotermes indicola (Wasmann)

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Ill 1 4111 5511zi 55gli 5 1581 ~_: 106 cm

I 8

Z• ~7 73 28 ~4 319

58

365

~:98 cm

gradient of the alternating magnetic field

Fig. 2. Average length in cm of vertical galleries built by Heterotermes indicola (Wasmann) in the four edges of containers placed in 2 rows with 1 cm distance from each other

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10

10

i'6

14

2

39 13

0,2

0,6 0,6

10,6

0,3 1

9

10,2

44 18 38 10 22

10,5

3 0,5 9 3 24

4 i 591

0,2 1 i 18

4 10 39

0,2 i 2 I

20 9 7 25 Ii 52 i 43

Fig. 3. Average daily length in cm of vertical galleries built by Heterotermes indicola-groups in the edges of 16 containers within 70 days. The gradient of the alternating magnetic field of the room decreases from left to right

Glesplatte glass plate (3mmdick) (3ram thick)

Gefaf~e polystyrene con ta,ne e

c L Polyu rethanschoum 1 ~_~ ~ ~po[yurethone foam

~ | Hotzblock L j wood block ~ ~

?cm I Hotzspanplotte wood particle hoard j / / / - / / / /

Y l 25cm

Betenblonk concrete block

Fig. 4. Experimental design with a glass plate separating 2 rows of containers

the new directions respectively. The position of vertical galleries is influenced by the direction and the gradient of very weak alternating magnetic fields. Such a field is produced by the heater of the air-conditioned room or can be generated in the Helmholtz-coil. Under this influence the termites build their galleries in the corners most remote from the source of the field, perceiving the minute differences in energy of the gradient over few centimeters distance (Becker, 1976a).

Arrangement of termite groups in 8 or 10 containers in two rows, as shown in Figure 2, with a distance of 1 cm between the rows and a 1 cm thick layer of polyurethane foam under the containers leads to gallery building almost only in the outside edges. The influence of the weak alternating magnetic field in the room is evident; Figure 2 shows one example of the results.

If 16 groups are kept together, as shown in Figure 3, gallery building is largely suppressed and very limited in the 4 central containers. In the outer containers the average length of the galleries is much greater in the edges farthest away from the center of the group than in the inner ones. The example in Figure 3 shows the influence of the alternating magnetic field of the room on the position of galleries built. Termite groups kept at a distance of 10 cm or more from the collective of 16 and from other individual groups produced longer galleries than the 12 groups at the perimeter of the 16.

In order to find out whether a chemical, thermal or vibrational influence produced by the termites caused reduced gallery building in the centre of groups and the directional preference of the outer positions, several experiments with insulating materials were carried out. In one case 16 groups were divided by 5 mm thick layers of polystyrene foam and placed on the same material. The reaction of the termites remained similar.

In experiments parallel to those described in Figure 2 the two rows of 5 containers were divided by a 3-mm-thick glass plate which rested 3 cm deep in a wood block and was 30 cm high and 51 cm long, thus 20 cm higher than the plastic containers and 16 cm longer than their rows on both sides (Fig. 4). Any possible chemical influence on directional behaviour of the termites in the two rows was thus excluded. The containers did not touch the glass plate nor did the foam layers, so that the conduction of temperature and vibration was very unlikely. Also under these condi- tions the termites reacted to the influence of the termite groups on the other side of the glass plate (Fig. 5). Competitive or cumulative effects of the weak alter- nating magnetic field and the influence of the termites could again well be observed as the summaries (ZX) of gallery lengths in the examples of Figure 5 show.

33 1

3 12 15. 14 8 16 2:145cm

glQss p[ote /

r "7 6t 18 iZ 22 1 7 2:122cm

mm ~ grGdient of theoHernating magnetic [ietd mm

E:197 cm gloss plote

12 ~.: 54 cm

Fig. 5. Average daily length in cm of vertical galleries built by Heterotermes indicola-groups under the experimental conditions shown in Figure4 with different direction of the gradient of an alternating magnetic field in the room. Both tests were carried out at the same time

4 30 2 16 25

ii[ 89 3 ~2 U 1 / 1 9 12

II Fig. 6. Average daily length in cm of vertical galleries built by Heterotermes indicola-groups in 16 containers separated by alu- minium-plates within 7 days. The gradient of the alternating magnetic field of the room decreases from left to right as in Figures 2 and 3

When 16 termite groups were separated by 5 - m e - thick a luminium plates with a plate of the same material being placed under the containers and the metal grounded, the reaction of termite groups to neighbouring ones was completely suppressed (Fig. 6). The distr ibution of the galleries and their average length in the individual containers was found to be random. It was only in the outer containers, that an

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influence of the alternating magnetic field could be stated. Another separation, i.e. a special silver con- taining paint figure on 3 me- f iberboard , which shields electric but not alternating magnetic fields resulted also in gallery building direction at random, but the influence of the alternating magnetic field was then observed in the central containers, too (Fig. 7).

F r o m these and a number of other experiments it became evident, that the reaction of termites on neigh- bouring groups is caused by physical fields. These are probably not al ternating magnetic fields no r - -because of the moist env i ronment - - s ta t ic electric fields and most likely not electromagnetic fields. Alternating electric fields of low energy, however, influenced the directional behaviour of termites like the biofields. These are most p robably alternating electric fields of low energy.

Warncke (1975) demonstrated, that alternating electric fields produced by flying bees are perceived by other individuals. The observation that termites produce and react to alternating electric fields is thus not the first observat ion with insects, while the influence of alternating magnetic fields on insects was unknown before this was found with termites (Becker, 1976a).

GIIU 451] 761i 18 3 57

4 9 17 JlJ[ 3 122

1141] 14 ]I 58 116 23

31

13

I0

6 142

50

6

4 46

ell ?t 1 2 Ii0 52 3~2_______~UL~ ~o

Fig. 7. Average daily length in cm of vertical galleries in 16 con- tainers separated by a material which shields electric but not magnetic fields within 7 days. The gradient of the alternating magnetic field of the room decreases from left to right as in Figures 2 and 3. The experiments of Figures 3, 6, and 7 were started at the same day. They represent one example

With regard to gallery building the response to biofields as well as to alternating magnetic and artificial alternating electric fields is a centrifugal reaction. This directional behaviour of termites pre- vents gallery building in the center of the nest and induces the workers to become active in the outer zones of the nesting area in their search for food and water supply. W o o d consumpt ion by the individual

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colonies is not influenced by neighbouring groups and is the same in the central ones of 16 containers as in outer ones or in isolated containers. Also other experiments, not described here, showed, that food consumption and gallery building activities are in- fluenced by various physical conditions differently (Becker, 1976b).

References

Becker, G.: Magnetfeld-Einflul3 auf die Galeriebau-Richtung bei Termiten. Naturwissenschaften 58, 60 (1971)

Becker, G. : Uber den Galeriebau yon Termiten. Z. angew. Entomol. 70, 120--133 (1972)

Becker, G.: Reaction of termites to weak alternating magnetic fields. Naturwissenschaften 63, 201 (1976a)

Becker, G.: Influences of magnetic, electric, and gravity fields on termite activity. Mater. Organismen, Beih. 3, 407--418 (1976b)

Warncke, U.: Insekten und V/Sgel erzeugen elektrische Felder. Um- schau 75, 479 (1975)

Received: November 7, 1976

Prof. Dr. Gtinther Becker Bundesanstalt ftir Materialpriifung Unter den Eichen 87 D-1000 Berlin 45