Influence of pollen deprivation on the fore wing asymmetry of honeybee workers and drones
Influence of pollen deprivation on the fore wing asymmetry of honeybee workers and drones
SZENTGYÖRGYI 0
Krystyn 0
CZEKOŃSKA 0
m TOFILSKI 0
0 Department of Pomology and Apiculture, University of Agriculture in Kraków , Al. 29. Listopada 54, 31-425, Kraków , Poland
- Environmental stress during development can be linked to changes in morphological traits of the organism such as increased fluctuating asymmetry. In suboptimal conditions, like food deprivation, developmental stability may be perturbed, because organisms are not able to buffer disturbances caused by stressors and, in effect, greater degrees of asymmetry can arise during development. In this study, honeybee workers and drones were reared in colonies with limited and unlimited access to pollen. The developmental instability of the workers and drones in these colonies was assessed using the asymmetry of their fore wing venation. Both workers and drones showed a similar directional asymmetry of size-in favour of the right wing-and significant, but dissimilar, differences of wing shape. Limited access to pollen caused some differences in the fluctuating asymmetry of size and shape in pollen-deprived workers and drones compared to the control bees. However, more pronounced differences were found due to replication than to pollen deprivation itself.
1. INTRODUCTION
Pollen is the main source of proteins, lipids,
vitamins and minerals for both the developing
brood and adult honeybees (Apis mellifera
Linnaeus, 1758)
(Brodschneider and Crailsheim
2010; Haydak 1970; Keller et al. 2005a, b)
.
Young worker larvae are fed with royal jelly,
however, in older workers and drone larvae it is largely
replaced with raw floral pollen
(Haydak 1970;
Hrassnigg and Crailsheim 2005)
. The pollen is also
consumed by adult drones in small amounts during
the first few days after emergence
(Free 1957;
Haydak 1970; Szolderits and Crailsheim 1993;
Schmickl and Crailsheim 2004)
, while adult
workers feed on pollen for a significantly longer
period of time and consume much larger amounts
of pollen
(Szolderits and Crailsheim 1993;
Hrassnigg and Crailsheim 2005)
.
In natural conditions, the availability of pollen
changes seasonally because it depends on the
diversity and abundance of flowering plants
(Köppler et al. 2007; Odoux et al. 2012)
. During
dearth periods or unfavourable weather
conditions, honeybees depend on pollen stores (Fewell
and Winston 1992); however, occasionally these
stores can be insufficient and bees can suffer from
malnutrition. The quantity of pollen available in
the hive during brood rearing can directly affect
t he de ve l o pm e nt o f w or ke r s an d dr one s
(Hrassnigg and Crailsheim 2005; Kunert and
Crailsheim 1988; Mattila and Otis 2006a)
.
Workers suffering from pollen deprivation in most
studies were found to live shorter
(Janmaat and
Winston 2000; Kunert and Crailsheim 1988;
Mattila and Otis 2006b)
, start foraging earlier
(Rueppell et al. 2006; Schmickl and Crailsheim
2002)
, have reduced hypopharyngeal glands
(Crailsheim and Stolberg 1989)
and ovaries
(Pernal and Currie 2000)
, less effective in flight
(Brodschneider et al. 2009)
and have lower levels
of vitellogenin and transferrin expression
(Di
Pasquale et al. 2013)
. Dwindling pollen stores
during autumn is also a signal for bees to start
rearing winter bees
(Mattila and Otis 2007)
.
Among drones, limited access to pollen reduces
their reproductive quality (
Czekońska et al. 2015
)
and mating success
(Couvillon et al. 2010)
. Pollen
limitation can also affect bees’ susceptibility to
Nosema spp.
(Wang and Moeller 1970; Huang
2012; Di Pasquale et al. 2013)
, Varroa destructor
(Huang 2012; van Dooremalen et al. 2013)
and
other diseases
(Brodschneider and Crailsheim
2010; de Grandi-Hoffman et al. 2010; Willard et
al. 2011; Foley et al. 2012)
. In extreme cases,
pollen deprivation can lead to the cannibalism of
young larvae in order to feed older larvae
(Schmickl and Crailsheim 2004)
or cessation of
brood rearing completely, to avoid producing
highly impaired individuals
(Imdorf et al. 1998;
Kunert and Crailsheim 1988; Crailsheim and
Hrassnigg 1998; Boes 2010)
.
Malnutrition, as described above, is a strong
exogenous stressor affecting development and
can be linked to changes in various morphological
traits. One of these traits is the body symmetry of
an organism. It is assumed that in suboptimal
conditions developmental stability may be perturbed,
because organisms are not able to buffer
disturbances caused by exogenous environmental
stressors and, as an effect, greater degrees of
randomly appearing asymmetry arise during
development. Such asymmetry caused by suboptimal
developmental conditions is called fluctuating
asymmetry and is independent of body side
(van Valen
1962)
and can affect various body parts
(Palmer
and Strobeck 2003; Palmer 1994)
. It should not be
confused with directional asymmetry
(van Valen
1962; Palmer 1994)
which occu (...truncated)