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Myrmecologische Nachrichten 9 27 - 32 Wien, Dezember 2006
Weather conditions during nuptial flight of Manica rubida (LATREILLE, 1802)
(Hymenoptera: Formicidae) in southern Poland
Łukasz DEPA
Abstract
Nuptial flight of many ant species occurs when weather conditions are appropriate; defined weather parameters may
even initiate it. Various ant species have different seasons of nuptial flight but in Poland most of them take place in sum-
mer. Nuptial flights of Manica rubida (LATREILLE, 1802) were observed in Piekary Śląskie (Upper Silesia, Poland) in
May 2004 and 2005, and also in April and May 2006. Obtained data suggest that appropriate weather conditions may
be necessary for alate sexuals of this species to begin their nuptial flight.
The question of reliability of literature data on nuptial flight dates is highlighted. According to literature, nuptial flight of
M. rubida has a broad time range (from April to September). Overall, weather and climatic conditions, also in context
with the semi-claustral mode of colony founding in this species may serve as an explanation of such discrepant reports.
Key words: Manica rubida, nuptial flight, mating, swarming, phenology.
M.Sc. Łukasz Depa, Zoology Department, Faculty of Biology and Environmental Protection, University of Silesia,
Bankowa 9, PL-40-032 Katowice, Poland. E-mail: lukasz.depa@wp.pl
Introduction
Nuptial flight has tremendous importance for ants. Not on-
ly does it facilitate copulating by unrelated sexuals, but it
also allows young gynes to disperse and to find new loca-
lities for nesting. During appropriate weather alate gynes
may even pass mountain barriers and settle down on ter-
ritories beyond the continuous ranges of their species. A
worker of Messor structor (LATREILLE, 1798) found in
Poland (KRZYSZTOFIAK 1984) is a prime example of this
phenomenon. This species is distributed from Southern
Europe to Central Asia and although it is a permanent in-
habitant of Central Europe, it appears in Poland only oc-
casionally, when young gynes manage to pass the Carpa-
thians and establish a colony before winter comes. It may be
assumed that in Poland such colonies do not survive win-
ter (SEIFERT 1996, CZECHOWSKI & al. 2002).
The occurrence of nuptial flight is affected by the
weather in two different ways. First, the local climatic con-
ditions (depending on altitude and latitude), especially the
period over which temperatures are sufficiently high for a
proper development of the sexual brood, may influence
the date when alates emerge. Second, appropriate weather
during the nuptial flight is required. It often happens that
the nuptial flight of some species takes place on the same
day over a very vast area. It is believed that highly speci-
fic weather conditions may act as the trigger to start nup-
tial flight (SUDD 1967). It is also known that different ant
species have different requirements concerning the wea-
ther to begin nuptial flight (BOOMSMA & LEUSINK 1981).
In the temperate climatic zone most ant species have their
nuptial flights during the summer months, especially from
June to August, rarely in May or September (see CZECHOW-
SKI & al. 2002).
Manica rubida (LATREILLE, 1802) is distributed in Eur-
ope, Asia Minor and the Caucasus, where it occurs main-
ly in the mountains (PISARSKI 1975, CZECHOWSKI & al.
2002), reaching 2400 m a.s.l. (KUTTER 1977). In Poland it
often inhabits uplands; it is also common in cities in the
southern part of the country, e.g., it is very abundant in Pi-
ekary Śląskie (Upper Silesia) (Ł. Depa, unpubl). Manica
rubida builds nests in the ground, often under stones or flag-
stones, in dry sunny areas, sparsely overgrown by xerophil-
ous vegetation (PISARSKI 1975, CZECHOWSKI & al. 2002).
Sexuals of M. rubida appear in the nests at the end of Ju-
ly and in August (WOYCIECHOWSKI 1985). The same is ob-
served in Upper Silesia, but in autumn no nuptial flights
have ever been noticed (see CZECHOWSKI & al. 2002).
The mode of colony founding is semi-claustral (WIL-
SON 1971), which means that young gynes are isolated in
their chambers but occasionally leave them to find food for
their growing brood.
The aim of this study was to define weather conditions
during the nuptial flight of Manica rubida and to attempt
to establish precisely what weather parameters are required
to initiate it.
Material and methods
The research was carried out in Piekary Śląskie (18° 58' E,
50° 24' N). Observations were conducted every day from
15 April to 4 June in 2004 and in the same period in 2005
and 2006. The periods were chosen deliberately so that they
spanned the earlier observed dates of nuptial flight (DEPA
2004). The study area was about 2000 m2, covered by hard
soil, at a housing estate's outskirts, surrounded in the west
by a row of high trees. The choice of the place was delibe-
rate, as in the earlier years it was observed to be a land-
ing area of alate gynes of M. rubida after swarming.
Observations of males and gynes flying up in the air
from the nests situated near the study area and alate gynes
landing on the study area were taken as indicators of
nup ial flight. Alate gynes appearing on the ground in the
t
Fig. 1: Weather parameters (maximum and minimum temperature) and the number of alate gynes counted in the study area
during the research period in 2004.
study area between 9:00 and 12:00 AM GMT were count-
ed. Meteorological data (temperature, wind velocity, air
pressure, relative humidity – each measured 2 m above soil
surface) were obtained from a meteorological station at the
nearby Pyrzowice airport, which is situated 11 km north-
east of Piekary Śląskie. Standard deviation was calculated
for days with and without nuptial flight. Student's t-test
was used to analyse the differences in mean temperature,
humidity, wind velocity and air pressure values for days
with and without nuptial flight.
Results
During the research, a total of 113 alate gynes were count-
ed (32 in 2004, 38 in 2005 and 43 in 2006). The numbers
of recorded gynes and the weather conditions (maximum
and minimum temperature) are presented in Figures 1, 2,
and 3. Table 1 presents average, minimum and maximum
weather parameters for days with and without nuptial flight.
Nuptial flights began in morning hours, between 7:30
and 10 AM GMT, most often from 8:30 to 9:30 AM GMT,
during sunny, warm days, when clouds did not diminish
the sunshine. Alate sexuals (males and alate gynes at the
same time) were flying in the air either after climbing grass
blades or directly from the ground. First alate gynes were
recorded in the study area about 10:00 AM GMT, which
means that they were landing at least one hour after the
nuptial flight began. The most preferable days were of low-
er than average humidity and higher than average day tem-
perature (Tab. 1). The standard deviation (SD) values for
temperature and humidity were significantly lower for days
with nuptial flight than for days without it. This means that
those two weather parameters tended to be more stable on
days with nuptial flight. Also, Student’s t-tests indicated
that the differences in mean values of temperature and hu-
midity for days with and without nuptial flight were sta-
tistically significant (P < 0.001 for both parameters). The
average atmospheric pressure and average wind velocity
during the nuptial flight did not differ significantly from
the average for days without nuptial flight. Mean values of
those two weather parameters for days with nuptial flight
were close to the average for days without nuptial flight
and SD values did not show consistent and significant dif-
ferences.
Swarming usually took place when the "warm sector"
of the low-pressure area was over the study area, when
warm air masses flowed in, preceding the cold atmospher-
ic front. Nuptial flights were also undertaken when the an-
ticyclonal weather was established and strong convection
was developing. In all years ample rain was normally ob-
served later on the same day or on the next day after the
nuptial flight. This is illustrated in Figures 1, 2, and 3 by
the significant decline in maximum temperature directly
after flights.
In the course of this study, no males were observed in
the study area where alate gynes were counted. 15 - 30 mi-
nutes after landing alate gynes shed their wings and started
digging chambers, often in short distances from each o-
ther sometimes < 1 m.
,
28
Fig. 2: Weather parameters (maximum and minimum temperature) and the number of alate gynes counted in the study area
during the research period in 2005.
Tab. 1: Daily weather parameters (day temperature, air pressure, relative humidity, wind velocity) on days with nuptial flights
and on days without nuptial flights, measured over the study period (n – number of days, SD – standard deviation).
2004
2005
2006
days with
nuptial flight
(n = 5)
days without
nuptial flight
(n = 46)
days with
nuptial flight
(n = 7)
days without
nuptial flight
(n = 44)
days with
nuptial flight
(n = 7)
days without
nuptial flight
(n = 44)
avera
g
e
│
SD 22.40 1.52 16.61 3.91 24. 00 3. 96 16.11 6.69 21.14 1.75 16.58 3.94
maximu
m
25.00 24.00 28.00 32.00 24 25.00
tempera-
ture [°C]
minimu
m
21.00 7.00 18.00 5.00 19 7.00
avera
g
e
│
SD 1010.00 14.82 1013.96 7.31 1015.14 3. 39 1014.45 7.41 1019.86 4.85 1015.68 4.87
maximu
m
1026.00 1026.00 1021.00 1027.00 1028.00 1028.00
air pres-
sure [hPa]
minimu
m
993.00 995.00 1010.00 996.00 1015.00 1005.00
avera
g
e
│
SD 61.00 4.38 69.00 10.53 62.00 7.99 68.00 13.00 51.29 5.31 69.00 9.83
maximu
m
68.00 94.00 76.00 99.00 60.00 92.00
relative
humidity
[%] minimu
m
56.00 46.00 51.00 40.00 44.00 53.00
avera
g
e
│
SD 2.23 1.48 2.62 1.39 1. 90 1. 02 2.18 1.73 3.96 0.78 3.70 1.63
maximu
m
3.90 5.80 3. 06 6.39 4.72 7.72
wind
velocity
[m/s] minimu
m
0.55 0.00 0. 83 0.00 2.58 1.03
29
Fig. 3: Weather parameters (maximum and minimum temperature) and the number of alate gynes counted in the study area
during the research period in 2006.
Discussion
This study shows that appropriate weather conditions may
act as a trigger for the nuptial flight of M. rubida. Swarm-
ing did not take place until specific weather parameters had
been established (see differences in SD values for days with
and without nuptial flight), especially with regard to tem-
perature. Swarming was observed on days when maximum
day temperature reached at least 18 °C, but preferably ex-
ceeded 20 °C, and when relative humidity was not higher
than 76 %, preferably about 60 %.
Interestingly, not always all sexuals took advantage of
the very first acceptable day: While in 2004 and 2005 the
first acceptable day, which was already a very warm one,
was chosen by the highest number of alate gynes, in 2006
many alate gynes did not swarm on a series of acceptable
but only moderately warm days but performed their nup-
tial flight on the very warmest day, which was at the end
of the nuptial flight period. This is remarkable because the
brood of gynes choosing the first day suitable for a nuptial
flight may be about 2 - 3 weeks ahead in development com-
pared to brood of gynes copulating at a later time. Since
young gynes land on the same area in great numbers, there
must exist a severe intraspecific competition among them,
and later among developing incipient colonies. In view of
this, the earlier young workers emerge, the greater chance
they stand of eliminating neighbouring nests.
If nuptial flight, in the extreme, occurs in late summer
or autumn, young queens may not manage to rear workers
before winter. If this is the case, they have to overwinter
with their brood (KIPYATKOV 1993), or wait with laying
the eggs until spring. Probably, overwintering without wor-
kers is more risky for them than overwintering in the par-
ental nest. And indeed, it has been observed in Upper Sile-
sia that although young sexuals appear in July and August
(Ł. Depa, unpubl.; similarly in mountainous areas: WOY-
CIECHOWSKI 1985) they do not swarm the same year al-
though the likelihood of similar weather conditions in Sep-
tember and in May is high for most parameters, the average
September temperature in Upper Silesia even being about
0.5 °C higher than the May temperature; only insolation is
weaker in September. In mountainous areas, where M.
rubida mainly occurs, nuptial flight may be postponed to
June or even July of the year after sexuals emerged.
Weather conditions during the nuptial flight, especially
temperature and sunlight, are important for sexuals to reach
sufficient body temperature to fly into the air. Because
gynes of M. rubida are big and massive, heat makes the fly-
ing easier. BOOMSMA & LEUSINK (1981) show that bigger
gynes of Lasius niger (LINNAEUS, 1758) and L. flavus (FA-
BRICIUS, 1782) need higher air temperature to fly than smal-
ler ones of Myrmica scabrinodis NYLANDER, 1846 and M.
rubra (LINNAEUS, 1758). Probably, the same rule also con-
cerns gynes of M. rubida, but this needs further investi-
gation.
It is interesting that M. rubida swarms mainly during dry
and hot weather, when the soil is hard, which makes dig-
ging the chamber difficult. Manica rubida is a species in-
habiting dry and sunlit places and such species often have
their nuptial flight after rainfall, when the soil is moistened,
30
so that it is easier to excavate (HÖLLDOBLER & WILSON
1990). In this study, however, there never was rainfall in
the 24 hours preceding flight but was often registered af-
ter the flight, either on the same or on the next day. Perhaps
such a sequence of weather events in some way enables
young gynes to find an appropriate locality to found the
nest.
Manica rubida has been reported to swarm either in
early spring, i.e., in April (PARAPURA & PISARSKI 1971,
CZECHOWSKI & al. 2002), or in May and June (FOREL 1915),
or from May to August (EMERY 1916), or even from July
to September (FOREL 1915, PARAPURA & PISARSKI 1971,
CZECHOWSKI & al. 2002). CZECHOWSKA (1976) found sex-
uals of this species in the Pieniny Mountains in the se-
cond half of July. ARAKELIAN (1994) observed sexuals in
nests in Armenia in June. It is not known whether data pre-
sented by a large number of authors are based on direct
observations of nuptial flights or only on observation of
dealate gynes. A. Buschinger (pers. comm.) observed fresh-
ly mated (confirmed by dissection) alate gynes of M.
rubida running on the ground in Aosta valley, Italy, c.
1700 m a.s.l., on 6.VI.2005, and B. Seifert (pers. comm.)
observed sexuals flying off from the nest in Austria, Ty-
rol, Landeck / Inn, on 15.V.1994. The author of this pa-
per observed the nuptial flight of this species in the Tatra
Mountains (c. 1200 m a.s.l.) in the middle of the first de-
cade of June 1996. Cited data refer to populations in dif-
ferent parts of M. rubida's geographic range, from mode-
rate and Mediterranean climatic zones. In view of this, the
existing inconsistencies of literature data may reflect dif-
ferent climatic conditions in various areas of M. rubida's
geographic range, which must affect the date of emerging
of sexuals and the beginning of nuptial flight.
Moreover, it is possible that the time of nuptial flight
was determined merely on the basis of observations of young
sexuals in the nests. Doubts of this kind have already been
aired in the case of a Central European Messor cf. struc-
tor (LATREILLE, 1798) population (SCHLICK-STEINER & al.
2005, 2006). It is known that sexuals of the closely related
genus Myrmica LATREILLE, 1804 emerge in summer and
start their nuptial flight in late summer and early autumn
(WOYCIECHOWSKI 1987, 1990). The same situation might
have been assumed for M. rubida. Because alate sexuals
appear in summer, many authors could expect them to
have their nuptial flight in late summer or in autumn.
Another source of inconsistencies of literature data on
the date of nuptial flight could be the fact that young queens
of M. rubida leave their chambers to find source of food.
This means that they can be observed on the ground for 2 -
3 months after their nuptial flight, the period it takes the
first workers to develop (STITZ 1939, Ł. Depa, unpubl.).
Assuming that the nuptial flight in the mountains takes
place in June, and that the first larvae appear one month af-
ter the flight, it is possible to find dealate gynes there out-
side their nests in search for food for their brood from the
beginning of July to the end of August. Such observations
might also have led many authors to report widely varied
dates of nuptial flights. Overall, it seems that reliability of
literature data on nuptial flight dates is a general problem
in myrmecology raised with regard to many ant genera (e.
g., Formica spp., B. Seifert, pers comm., Solenopsis fugax
and Lasius spp., A. Buschinger, pers comm.). In the case
of M. rubida, further systematic research needs to be con-
ducted to determine precisely the possible impact of wea-
ther and climatic factors on its mating behaviour and dis-
persal strategy.
Acknowledgements
First of all I wish to thank Prof. W. Czechowski and Prof.
A. Radchenko (Museum and Institute of Zoology, PAS) for
reviewing the first version of manuscript and useful com-
ments. Further, I am indebted to Prof. A. Buschinger and
Dr. B. Seifert for interesting data and the editors for pro-
viding literature and helpful comments. I also thank two
anonymous referees for all points of constructive criticism
which helped to improve the manuscript.
Zusammenfassung
Bei vielen Ameisenarten findet der Hochzeitsflug nur bei
passender Witterung statt, ja bestimmte Wettersituationen
können den Hochzeitsflug sogar auslösen. Unterschiedli-
che Ameisenarten fliegen zu unterschiedlichen Zeitpunk-
ten, aber in Polen findet der Hochzeitsflug der meisten
Arten im Sommer statt. Im Rahmen dieser Studie wurden
Flüge von Manica rubida (LATREILLE, 1802) in Piekary
Śląskie (Oberschlesien, Polen) im Mai 2004 und 2005,
sowie im April und Mai 2006 beobachtet. Diese Daten le-
gen nahe, dass M. rubida nur bei passender Witterung
Hochzeitsflüge unternimmt.
Die Frage nach der Verlässlichkeit von Literaturanga-
ben zum Zeitpunkt von Hochzeitsflügen wird diskutiert.
Publizierte Daten weisen für M. rubida Hochzeitsflüge
während eines langen Zeitraums (April bis September) aus.
Insgesamt könnten Diskrepanzen zwischen Literaturanga-
ben auf Klima und Witterung, auch in Zusammenhang
mit der semiklaustralen Nestgründung der Art, zurückzu-
führen sein.
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