LIGHT-TRAP CATCH OF THE FLUVIAL TRICHOPTERA SPECIES IN CONNECTION WITH THE GEOMAGNETIC
AUTHORS’ CONTRIBUTIONS
This work was carried out in collaboration between all authors. All authors read and approved the final manuscript.
Received: 1st October 2015 Accepted: 4th November 2015 Published: 24th November 2015
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ABSTRACT
The study deals with the change of light-trap catch of twelve caddisfly (Trichoptera) species of Danube and Tisza rivers in connection with the geomagnetic horizontal component (H-index). The numbers of specimens caught of all species were calculated relative catch values. These daily relative catch data were assigned to the daily values of geomagnetic field above 21,250 nT (H-index). We correlated the daily catch results pertaining to the daily values of geometric H-index values.
The catch of nine species increased in parallel with increasing values of the H-index, but the catch of two species declined. There was one species which has decreasing catch at River Danube, but it was increasing at River Tisza.
Keywords: Trichoptera; light-trap; geomagnetic horizontal component.
1. INTRODUCTION
Studying some species of termites (Isoptera), beetles (Coleoptera), flies (Diptera), orthopteroids (Orthoptera), and hymenopterans (Hymenoptera), Becker [1] found that they orient according the natural magnetic field. Way of their mobility is North-South, rarely East-West. Their original way of movement could be modified by artificial magnetic field.
Iso-Ivari and Koponen [2] studied the impact of geomagnetism on light trapping in the northernmost part of Finland. In their experiments they used the K index values measured in every three hours, as well as the ΣK and the δH values. A weak but significant correlation was found between the geomagnetic
parameters and the number of specimens of the various orders of insects caught. Studying the few Willow Ermine (Yponomeuta rorella Hbn.), Pristavko and Karasov [3] revealed a correlation between the C and ΣK values and the number of individuals caught.
In a later study [4] they also established that at the time of magnetic storms ΣK has a greater influence on the flying activity of the above species. The influence is also significant in years when ΣK is not higher than 16-26. Equally interesting is the observation that if ΣK < 26, flying activity intensifies the same day, if ΣK = 27-30, this happens the following day and if ΣK
= 33-41, intensification follows only on the second or third day. Studying the termite species Heterotermes indicola Wasmann, Becker and Gerisch [5] found a stronger correlation between this activity and the
Nowinszky et al.; JOBAN, 4(4): 206-216, 2015
207 vertical component of geomagnetism (z) than with the values of the K index. Tshernyshev and his colleagues have discussed in a series of studies the results of their laboratory and light trapping experiments with species of different orders of insects to reveal a connection between geomagnetism and certain life phenomena.
Tshernyshev [6] found that the number of light-trapped beetles and bugs rose many times over at the time of geomagnetic storms in Turkmen. He found a high positive correlation between the horizontal component and the number of trapped insects. It was also observed by him [7] that the number of light-trapped insects significantly raised at the time of magnetic perturbations. Later, however, he reported that while light-trap catches of some Coleoptera and Lepidoptera species increased, that of other Lepidoptera and Diptera species fell back during magnetic perturbations [8,9]. Based on international literature and his own results, published a comprehensive study to give a summary of the latest state of knowledge on the relation between geomagnetism and the activity of insects [10].
Examinations over the last decades have also Kecskemét fractionating light-trap, we have examined the light trapping of Turnip Moth (Agrotis segetum Den. et Schiff.), Heart & Dart (Agrotis exclamationis L.) and Fall Webworm Moth (Hyphantria cunea Drury) in relationship with the horizontal component of the geomagnetic field strength [13].
According to the authors of recent publications [14]
and [15] the orientation/navigation of moths at night may becomes not by the Moon or other celestial light sources, but many other phenomena such as geomagnetism.
The results of our calculations have shown that in the period of the New Moon when there is no measurable moonlight, the higher values of the horizontal component are accompanied by a falling relative catch. In the other moon phases, i.e. in the First Quarter, Full Moon and the Last Quarter, growing values of the horizontal component are accompanied by an increasing catch in both the moonlit and moonless hours [16,17].
However, we did not find any studies, to investigate the relationship between the Earth's magnetism and light-trap catch of caddisflies.
2. MATERIALS AND METHODS
The average field strength of the Earth as a magnetic dipole is 33,000γ. (1γ = 10-5 Gauss = 10-9 Tesla = 1 nanotesla (nT)). Geophysical literature uses γ as a unit.
Geomagnetic field strength can be divided into three
components: H = horizontal, Z = vertical and D = declination components. With regard to the
entomologic trials the extent of total field strength, on the one hand, and the value of horizontal component, on the other, are important because, insects fly rather horizontally than vertically.
The magnetic and geographic poles of the Earth do not coincide, therefore in addition of geographic;
there are also geomagnetic coordinates of latitude and longitude. The latter characterize the geomagnetic conditions of a given geographical location.
Geomagnetic parameters greatly differ in any given moment of time at the various points of the surface of the Earth. A distance of approximately 300 kilometres along the geomagnetic meridian may produce significantly different characteristics. These measurements are made at the Geodetical and Geophysical Research Institute of the Hungarian Academy of Sciences at Nagycenk (Geographical latitude: 47°38′41ʺN, longitude: 16°43′81ʺE), near Sopron and the Observatory of the Hungarian Loránd Eötvös Geophysical Institute at Tihany (Geographical latitude: 46°90′57ʺN, longitude: 17°89′42ʺE).
The geomagnetic measuring data of a single observatory in the case of Hungary supply sufficient information for the whole country: i. e. the parameters measured along the magnetic meridian (direction:
North-West to South-East) in function of time. The distance along the magnetic meridian never exceeds 300 km.
The geomagnetic data, measured in the whole Earth, were published by the Center for Data Analysis and Space Magnetism Graduate School of Science, Kyoto (http://wdc.kugi.kyoto-u.ac.jp/index.html). We downloaded the value of x and y index measured at Tihany by Hungarian Loránd Eötvös Geophysical Institute. We calculated the horizontal component (H index) values from these according to the advice of Mr. László Szabados using the following formula:
2 2 y x
H= +
We withdrew 21,250 from the calculated values as we did it in our previous works. We used the H-index-21250 data in our calculation.
Nowinszky et al.; JOBAN, 4(4): 206-216, 2015
208 The selected caddisflies specimens used in our investigations are originated from previous light-trap collections.
There was the most important point of view at the selection of species and swarming the total number of male and female specimens exceeds 700. The collection sites, their geographical coordinates and the years of collection are as follow: River Danube: Göd and a saving lid with a diameter of 1 metre. There was a collecting funnel under the lamp. Its diameter was 40 cm and this collector drove into a container. We used clear chloroform as killing material. Our light-traps operated in all years and on all settlements between 1st April and 31st October on all nights.
We mean a generation's flying period by swarming.
Than the number of individuals of a given species in different places and different observation years is not the same. The collection efficiency of the modifying factors (temperature, wind, moonlight, etc.) are not the same at all locations and at the time of trapping, it
is easy to see that the same number of items capture two different observers place or time of the test species mass is entirely different proportion. To solve this problem, the introduction of the concept of relative catch was used decades ago [20].
The relative catch (RC) for a given sampling time unit (in our case, one night) and the average number individuals per unit time of sampling, the number of generations divided by the influence of individuals. If the number of specimens taken from the average of the same, the relative value of catch: 1 [20].
From the collection data pertaining to examined species we calculated relative catch values (RC) by swarming of examined species. Following we arranged the data on the H-index in classes. Relative catch values were placed according to the features of the given day, and then RC were summed up and averaged. The data are plotted for each species and regression equations were calculated for relative catch of examined species and H-index data pairs. We determined the regression equations, the significance levels which were shown in the Figures.
3. RESULTS AND DISCUSSION
Our results are shown in the Table 1 and Figs. 1-12.
The light-trap catch of nine examined species increased in the higher values of the H-index. These
Table 1. The catching data (families, species, number of specimen and catching nights)
Families – species River Danube (Göd, 1999) River Tisza (Szolnok, 2000) Number of Number of
Specimen Nights Specimen Nights
Hydroptilidae
Agraylea sexmaculata Curtis, 1834 1,725 127
Ecnomidae
Hydropsyche bulgaromanorum Malicky, 1977 16,832 172 22,500 94
Brachycentridae
Brachycentrus subnubilus Curtis, 1834 4,004 129 Lepidostomatidae
Lepidostoma hirtum Fabricius, 1775 2,434 107
Limnephilidae
Limnephilus affinis Curtis, 1834 723 104
Halesus digitatus Schrank, 1781 1,238 105
Leptoceridae
Athripsodes albifrons Linnaeus, 1758 814 115
Ceraclea dissimilis Stephens, 1836 929 100
Setodes punctatus Fabricius, 1759 4,705 145 1,848 87
Notes: The taxonomic classification of the species was carried out according to Kiss ([21]
Most of the species, listed in the table, also were collected in Bükk Mountains by Kiss [22]
Nowinszky et al.; JOBAN, 4(4): 206-216, 2015
209 species are as follows: Agraylea sexmaculata Curtis Ecnomus tenellus Rambur, Neureclipsis bimaculata Linnaeus, Hydropsyche contubernalis Mc Lachlan, Lepidostoma hirtum Fabricius, Limnephilus affinis Curtis, Athripsodes albifrons Linnaeus, Ceraclea dissimilis Stephens and Setodes punctatum Fabricius.
The catch decreased of two species Brachycentrus subnubilus Curtis and Halesus digitatus Schrank when the value of H-index increased. Catching of the Hydropsyche bulgaromanorum Malicky declined at River Danube (area of village Göd, 1999), at River Tisza (area of city Szolnok, 2000) increased.
Fig. 1. Light-trap catch of the Agraylea sexmaculata Curtis in connection with the geomagnetic H-index (Szolnok, 2000)
Fig. 2. Light-trap catch of the Ecnomus tenellus Rambur in connection with the geomagnetic H-index (Szolnok, 2000)
y = 5E-06x3 - 0.003x2 + 0.5374x - 31.462 R2 = 0.9616 P < 0.001
0,80 0,90 1,00 1,10 1,20 1,30 1,40
160 170 180 190 200 210 220 230
Geomagnetic H-index
Relative catch
y = -3E-06x3 + 0.001x2 - 0.0855x - 1.3244 R2 = 0.9406 P < 0.001
0,40 0,50 0,60 0,70 0,80 0,90 1,00 1,10 1,20
165 170 175 180 185 190 195 200 205 210 215 220
Geomagnetic H-index
Relative catch
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210
Fig. 3. Light-trap catch of Neureclipsis bimaculata Linnaeus in connection with the geomagnetic H-index (God, 1999 and Szolnok, 2000)
Fig. 4. Light-trap catch of the Hydropsyche contubernalis Mc Lachlan in connection with the geomagnetic H-index (God, 1999 and Szolnok, 2000)
y = -5E-06x3 + 0.0028x2 - 0.4981x + 28.948 R2 = 0.9611 P < 0.001
0,40 0,50 0,60 0,70 0,80 0,90 1,00 1,10 1,20 1,30
160 170 180 190 200 210 220
Geomagnetic H-index
Relative catch
y = -5E-06x3 + 0.0032x2 - 0.6171x + 39.165 R2 = 0.9888 P < 0.001
0,50 0,60 0,70 0,80 0,90 1,00 1,10 1,20 1,30 1,40
150 160 170 180 190 200 210 220 230
Geomagnetic H-index (21250+values)
Relative catch
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211
Fig. 5. Light-trap catch of Hydropsyche bulgaromanorum Malicky in connection with geomagnetic H-index (God, 1999 and Szolnok, 2000)
Fig. 6. Light-trap catch of the Brachycentrus subnubilus Curtis in connection with the geomagnetic H-index (God, 1999)
connection with geomagnetic H-index (Göd, 1999 and Szolnok, 2000)
y = 8E-06x3 - 0,0049x2 + 0,9711x - 63,751 R2 = 0,9187
y = -4E-06x3 + 0,0019x2 - 0,3087x + 17,644 R2 = 0,9643
0,40 0,50 0,60 0,70 0,80 0,90 1,00 1,10 1,20 1,30
130 140 150 160 170 180 190 200 210 220 230
Geomagnetic H-index (nT)
Relative catch
Göd Szolnok Polinom. (Göd) Polinom. (Szolnok)
y = 4E-05x3 - 0.0257x2 + 5.2405x - 353.91 R2 = 0.7574 P < 0.01
0,80 0,85 0,90 0,95 1,00 1,05 1,10 1,15 1,20
185 190 195 200 205 210 215 220
Geomagnetic H-index
Relative catch
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212
Fig. 7. Light-trap catch of the Lepidostoma hirtum Fabricius in connection with the geomagnetic H-index (God, 1999)
Fig. 8. Light-trap catch of the Limnephilus affinis Curtis in connection with the geomagnetic H-index (Szolnok, 2000)
y = -3E-05x3 + 0.017x2 - 3.1892x + 198.93 R2 = 0.9814 P < 0.001
0,40 0,50 0,60 0,70 0,80 0,90 1,00 1,10 1,20 1,30
165 170 175 180 185 190 195 200 205 210 215 220
Geomagnetic H-index
Relative catch
y = 2E-05x3 - 0.0132x2 + 2.6409x - 176.37 R2 = 0.9384 P < 0.001
0,70 0,80 0,90 1,00 1,10 1,20 1,30 1,40
185 190 195 200 205 210 215 220
Geomagnetic H-index
Relative catch
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213
Fig. 9. Light-trap catch of the Halesus digitatus Schrank in connection with the geomagnetic H-index (Szolnok, 2000)
Fig. 10. Light-trap catch of the Athripsodes albifrons Linnaeus in connection with the geomagnetic H-index (Szolnok, 2000)
y = 1E-05x3 - 0.0076x2 + 1.4325x - 87.39 R2 = 0.9594 P < 0.001
0,60 0,70 0,80 0,90 1,00 1,10 1,20 1,30 1,40 1,50
150 155 160 165 170 175 180 185 190 195 200 205 210
Geomagnetic H-index
Relative catch
y = -9E-06x3 + 0.0047x2 - 0.7895x + 43.082 R2 = 0.9779 P < 0.001
0,40 0,50 0,60 0,70 0,80 0,90 1,00 1,10 1,20
170 175 180 185 190 195 200 205 210 215 220
Geomagnetic H-index
Relative catch
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214
Fig. 11. Light-trap catch of the Ceraclea dissimilis Stephens in connection with the geomagnetic H-index (Szolnok, 2000)
Fig. 12. Light-trap catch of Setodes punctatum Fabricius in connection with geomagnetic H-index (God, 1999 and Szolnok, 2000)
y = -5E-05x3 + 0.0265x2 - 5.0761x + 322.13 R2 = 0.9977 P < 0.001
0,40 0,50 0,60 0,70 0,80 0,90 1,00 1,10 1,20 1,30 1,40
170 175 180 185 190 195 200 205 210 215 220
Geomagnetic H-index
Relative catch
y = 0.0001x2 - 0.0345x + 2.6161 R2 = 0.8502 P < 0.01
0,40 0,50 0,60 0,70 0,80 0,90 1,00 1,10 1,20 1,30 1,40 1,50
150 160 170 180 190 200 210 220
Geomagnetic H-index
Relative catch
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215 4. CONCLUSION
In parallel to the higher Earth's magnetic horizontal component (H-index) and the increasing catch values probably can be explained with the fact, that in such cases the spatial orientation of the insects the Earth's magnetic field comes into view.
The increase or decrease of the catch is explainable by our previous hypotheses [20]. This opposite form of behaviour may be the many reasons. The claim and tolerance to environmental factors of the species are different. Environmental factors interact with each other to exert their effects. Thus the same factor can be different effect. The species have different survival strategy. Adverse effects of two possible answers:
passivity, or hiding or even increased activity, because you want to ensure the survival of the species. Therefore, the insect do "to carry out their duties in a hurry".
The fact that on the higher and increasing values of geomagnetic horizontal component the catches are not suddenly, but gradually decline, we deduce that the tolerance and response of insect specimens adverse effects to individually change.