Predation Cues in Solitary bee Nests
Predation Cues in Solitary bee Nests
Justyna Kierat 0 1
Michał Filipiak 0 1
Hajnalka Szentgyörgyi 0 1
Michal Woyciechowski 0 1
0 Department of Pomology and Apiculture, Faculty of Biotechnology and Horticulture, University of Agriculture in Kraków , Al. 29. Listopada 54, 31-425 Kraków , Poland
1 Institute of Environmental Sciences, Jagiellonian University , Gronostajowa 7, 30-387 Kraków , Poland
2 Justyna Kierat
Predation at the nesting site can significantly affect solitary bees' reproductive success. We tested female red mason bees' (Osmia bicornis L.) acceptance of potential nesting sites, some of which were marked with cues coming from predated conspecifics (crushed bees) or from a predator itself (rodent excreta). In our experiment, females did not avoid nests marked with either of the two predator cues. We suggest that bee females do not recognize these two cues as risky. Alternatively, costs of abandoning natal aggregation might be too high compared with any perceived predation risk of staying. Moreover, the presence of crushed bees can provide positive information about the presence of conspecifics and, possibly, information about a nesting aggregation that may be preferred by bees when choosing a nesting site.
Nesting; Osmia bicornis; predation; red mason bee; risk cues; solitary bees; rodents
Introduction
Prey animals minimize the risk of predation by various types of adaptations, like
morphological
(e.g. shape and size changes; Tollrian 1995)
, physiological
(e.g.
toxins; Williams et al. 2003)
, life historical (e.g. production of diapausing forms;
Ślusarczyk 2010) and behavioral ones
(e.g. by diminishing activity when the
probability of encountering a predator is high or by avoiding places with a high risk
of being attacked; Matassa and Trussell 2011; Suselbeek et al. 2014)
. Information about
predators can come from the predator itself
(e.g. kairomones; Kobak et al. 2010)
or
from other prey animals. The information provided by other prey individuals can be
either cues whose purpose is to warn others about the predation risk
(Seyfarth et al.
1980)
, or cues that are only by-products of the attack, but are perceived as a risk cue,
e.g. body fluids released from wounds
(Czarnoleski et al. 2010)
. The evolution of
dedicated signals that inform about risk is expected only if a signaler benefits from
alerting others (directly or by helping related individuals).
Honeybee and bumblebee workers avoid flowers marked with the scent of dead
individuals, and flowers on which they previously experienced unsuccessful
predator attack or where another bee was temporarily captured
(Abbott 2006;
Dukas 2001; Llandres et al. 2013)
. In the latter case, the communicating substance
evolved as a predator warning signal. When related females from the same colony
forage in one area and encounter their kin during foraging, exchange of
information between workers improves colony’s performance. Similar substances are not
expected to have evolved in solitary bees, which do not establish colonies of
related individuals. However, solitary bees still may react to the cues coming from
other individuals killed by a predator. According to theoretical models, solitary
bees are expected to accept lower risk during foraging than workers of social bees,
because their death is a definite end of their reproduction, in contrast to worker
bees whose fitness depends on reproduction of their kin in the colony
(Clark and
Dukas 1994; Rodríguez-Gironés and Bosch 2012)
. Thus, the response of solitary
bees to predation cues in the environment should be even stronger than that of
social bees. In fact, solitary bees have been shown to discover chemical and/or
visual cues that signal predator presence, and to modify their behavior to reduce
risk of being captured (Wcislo and Schatz 2003; Gonzálvez and
RodríguezGironés 2013). However, the reaction of solitary bees to predator risk cues is
poorly understood, and some results are contrary to expectations, indicating that
solitary bees may in fact respond to risk cues to a lesser degree than social bees
(Reader et al. 2006)
, for example by ignoring the olfactory information about a
predator
(Wcislo and Schatz 2003)
.
The places where bees are vulnerable to predator attack are primarily foraging
sites
(with predators waiting for their prey on flowers, e.g. spider crabs; Ings and
Chittka 2008; Reader et al. 2006)
and nesting sites that can be destroyed by birds
or rodents (Krunić et al. 2005). Choosing a nesting site is a particularly important
decision because developing bees are confined to one place for their entire
development and overwintering period
(Raw 1972)
. Nesting aggregations of bees
can persist for several seasons. It is possible that after discovering a nesting
aggregation, a predator will remember the exact location and return to feed in
that place again. Particularly, birds can remember locations where they recently
fed and return to them
(Clayton an (...truncated)