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**Corresponding author address: Jnos Pusks, Department of Physical Geography, Berzsenyi Dniel

College, H-9701 Szombathely, Krolyi Gspr square 4. Hungary; e-mail: pjanos@deimos.bdtf.hu

INFLUENCE OF METEOROLOGICAL EVENTS, MEASURED IN THE TOWN FOR

FLIGHT ACTIVITY OF MOTHS

Lszl Makra*, Jnos Pusks

**, Lszl Nowinszky

**

*University of Szeged, Szeged, Hungary;

**Berzsenyi Dniel College, Szombathely, Hungary

Abstract

The authors making use of the fortunate circumstances that a principal weather observation station is located in

Szombathely (Hungary), where a light-trap observation site was in operation from 1962 to 1970, have studied the

number of specimens of the straw-point moth (Rivula sericealis Scop.), which fly in masses into light, in

connection with a number of weather events. The authors examined the relation between the catch of moths and

the effect of the weather events listed in the section "Present time" (reducing cloudiness, constant cloudiness,

growing cloudiness, mist, fog, thunder and lightning, calm rain, calm rain with interruptions, shower of rain,

thunderstorm, rain has stopped, showers have stopped, thunderstorms have stopped) on the amount ofspecimens captured. Our most important result is as follows. Until now, we did not know that decreasing clouds,

and thunder and lightning preceding thunderstorms also increase the flight activity. The effect of rain in hindering

the catch is well known, but the fact that the hindering effect remains after the rain has stopped is a new finding.

We were also able to point out the adverse effect of mist and fog on the collection

Key words: light-trap, straw-point moth (Rivula sericealis Scop.), weather elements

1. INTRODUCTION

Researchers have examined the influence of the various weather elements on collecting by light-trap all over the

world. However, since these studies have been looking into climatic conditions that are basically different from the

ones prevailing in Hungary and in many cases not pertaining to the species found in this country, we do not go

into a detailed description of these.

In Hungary research into the interrelationship between the weather elements and the number of specimens

captivated began from the late 1950-ies. Initially, with the stock of collecting data still small, research was aimed

primarily at defining the value ranges that could be described as favourable or unfavourable for the flight activity

of the different insect orders. In this field, findings of basic importance have been published by Manninger (1948),

Wber (1957), later by Jrfs (1979) evaluated by species the influence of meteorological factors on the process

of swarming.

2. MATERIAL AND METHODS

Making use of the fortunate circumstance that there has been a meteorological main station and, in the years

between 1962-1970, there was also a light-trap in continuous operation in Szombathely, we studied the trends in

the light trapping of the straw-point moth (Rivula sericealis Scop.), a species flying from spring to autumn and also

one that flew to light in the biggest masses at the given place, also in interrelationship with the weather elements

not measured regularly anywhere else but at the main station. The light-trap collected 3100 specimens over 945

nights in 9 years.

We examined the effect of the weather events listed in the "present time" section on the quantity of the specimens

trapped: dwindling cloudiness, unchanged cloudiness, increasing cloudiness, vapour, fog, thunder and lightening,

quiet rain, quiet rain with interruptions, shower, stormy rain, rain has stopped, shower has stopped, storm has

stopped. All data were collected from the Yearbooks of the Central Meteorological Institute of the Hungarian

Meteorological Service.

The size of a population will be different at the various observation posts and the modifying factors are not

identical either at all the venues and times of light trapping, therefore it is easy to understand that catching the

same number of specimens at two different observation posts or at different points of time may stand for varying

proportions of the given population. Using relative catch values might solve this problem (Nowinszky, 1994).

Relative catch (RC) is the quotientof the number of individuals caught in a given sampling unit (1 hour or 1 night)

and the mean values of the number of individuals of the generation counted for the time unit of sampling. If the

number of specimens caught corresponds to the average, the relative catch value will be 1.

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Relative catch values for each generation were calculated from the daily number of straw-point moth (Rivulasericealis Scop.) specimens collected by light-trap. The respective relative catch values were correlated with eachvalue of each weather element, then they were arranged in classes. In each class, we averaged the values of theweather elements and formed three point weighted moving averages from the relative catch data. Then, to reveal

any possible connection, we made correlation calculations between the weather elements regarded as independentvariables on the one hand and the weighted moving averages of the relative catches on the other. We alsocalculated the difference of the average of each class from the average value calculated from the sum-total of all theother data. The relative catch values belonging to numerically unmeasurable weather situations (the events of the"present time") were also averaged, then the significance level of their deviation from the average relative catch(expected value) of all the other observations was checked with a T-test.

3. RESULTS

The effectiveness of light trapping straw-point moths (Rivula sericealis Scop.) in the context of "present time"

weather phenomena in Table 1.

Table 1.

Light-trap catch of the straw-point moth (Rivula sericealis Scop.) in connection with "present time"weather events at the time of observation

Weather events of present timeRelativecatches

Number ofdata

Significancelevel (%)

Decreasing cloudiness 1.101 1078 95

Unchanged cloudiness 1.062 789

Increasing cloudiness 0.987 863

Vapour 0.929 303 95

Fog 0.743 38 95

Thunder, lightning 1.278 131 95

Calm rain 0.663 219 99

Calm rain with gaps 0.791 72 95

Shower of rain 0.639 27 95

Thunderstorm 0.773 54 95

After calm rain 0.995 28After thunderstorm 0.552 22 95

After rain 0.677 87 95

4. DISCUSSION

We have managed to reveal the modifying effect on the catch of the so-called "present time" weather

phenomena, i.e. those taking place at the time of the observation.

We had no knowledge of the fact that diminishing cloudiness as well as thunder and lightening preceding a

thunderstorm also enhance flying activity. Information regarding the modifying effect of precipitation has also

become more accurate. The role of rain in impeding the flight of insects is well known, but it is new information

that this hindering influence make its effect felt even after it stops raining. There is a significant rise in the catchduring lightning and thunder preceding a storm, the catch drops by half during the storm and stays low even after

the storm is over.

References

Jrfs, J., 1979, Forecasting of harmful moths by light-traps (in Hungarian), PhD Thesis. Kecskemt. 127.Manninger, G.A., 1948, Connection between the climate, weather and the harmful animals (in Hungarian), In: Rthly,A., Aujeszky, L., 1948,Agrometeorology. Quick. 424.Nowinszky, L. [ed.], 1994, Light trapping of insects influenced by abiotic facors. Part I. Savaria University Press.155.Wber, M., 1957, The role of meteorological parameters in life of insects (in Hungarian)., Pcsi Muszaki Szemle.3:17-23.