Videos of nests of Harpagoxenus sublaevis and Leptothorax acervorum containing Leptothorax acervorum workers transferred as pupae into different social environments i.e. colonies
<p><strong>Ant collection and colony maintenance</strong></p>
<p>Colonies of the hosts <em>Leptothorax acervorum</em> and <em>L. muscorum</em> and the dulotic ant <em>Harpagoxenus sublaevis</em> were collected in July 2020 close to Nuremberg, Germany (49.345592, 11.258971 and 49.413857, 11.026181). At the University of Mainz, ants were transferred to plastered nest boxes containing artificial nest sites consisting of a Plexiglas cavity sandwiched between two microscope slides (7.5 cm x 2.5 cm x 0.5 cm) covered with a red foil and kept at 18°C with a 12:12 light: dark cycle. Ants were fed with crickets and honey every fourth day and provided with water ad libitum.</p>
<p><strong>Experimental manipulation</strong></p>
<p>For our experiment, we selected ten colonies of <em>L. acervorum</em> and five colonies each of <em>L. muscorum</em> and <em>H. sublaevis</em>. Colonies were assigned to one of five replicates, each replicate containing one colony for each of the four treatments. We prepared experimental colonies by standardizing colony size to one queen, 15 small larvae and 30 adult workers (15 inside + 15 outside workers). Adult workers were marked with a thin metal wire between thorax and abdomen (0.02 mm diameter, Elektrisola, red) to allow distinguishing them from our focal newly emerged workers. We removed 24 pupae from each <em>L. acervorum</em> colony, of which six were returned to the natal colony (referred to as “original” treatment), and six each were transferred into another <em>L. acervorum</em> colony (“conspecific” treatment), into an <em>L. muscorum</em> colony (“heterospecific” treatment) and a colony of <em>H. sublaevis </em>(“parasitic” treatment). For the parasitic treatment, we standardized the number of host workers to 60 as described above, but additionally added all <em>H. sublaevis</em> ants (18.4 ± 13.56 adult female individuals). Workers of these obligate social parasites do not take over worker chores, such as brood care and foraging, which are outsourced to host workers. Unfortunately, worker pupae from two of our replicates did not develop into adult workers in sufficient numbers, so that we focused our transcriptomic analyses on workers from the remaining three replicates. Moreover, all<em> L. acervorum </em>pupae transferred into <em>L. muscorum</em> colonies (“heterospecific” treatment) were either killed or expelled from the colony or did not emerge into workers (Survival: Kruskal-Wallis p = 0.05; Rejection (pupae outside the nest over the first three days): Kruskal-Wallis p < 0.001, Wilcoxon Heterospecific-Parasitic p = 0.016, Wilcoxon Heterospecific-Conspecific p = 0.012, Wilcoxon Heterospecific-Original p = 0.004) indicating that <em>L. muscorum</em> not only recognise <em>L. acervorum </em>pupae, but also eliminate them from their colonies. While we were unable to include this heterospecific treatment thus in our analyses, the number of transferred individuals still alive at the end of the experiment did not differ between the remaining treatments (Kruskal-Wallis: p = 0.34). Rejection was calculated as the number of pupae outside the nest over the first three days.</p>
<p><strong>Behavioural observations</strong></p>
<p>About 10 weeks (63-69 days) after the emergence of the first worker, colonies were transferred to 22°C and the red foil from their glass nest was removed to allow workers to adapt to light. The next day, the slide nest was transferred to a fluon-treated arena (3 cm x 7.5 cm) and each colony was filmed for 100 min in 4k using a SONY FDR-AX33 camera under a Leica KL1500 LED light.</p>
opencc-by-4.0Aug 2022View details →
