Housing the milkweed bugs
We placed the milkweed bugs into a 30 x 16 x 21 cm arena at room temperature (~21℃) under a black roof. We gave the bugs shelled sunflower seeds in a dry petri dish as their source of food and water from a cotton stopper on a test tube filled with water as their source of water. We placed the bugs on a 8L:16D day-night cycle and allowed them vision of their surroundings through the plastic walls of the arena.
Setting up the experiment
Twelve hours prior to the experimental setup we starved the milkweed bugs by removing the sunflower seeds from their arena. We took a 34 x 29 x 24 cm cardboard box and lined it with a black rubbish bag. We covered the bottom of the box with a layer of ice chunks. We placed a 30 x 16 x 21 cm arena with a blue roof into the box and packed the cleft between the box and the arena with ice. We lined a 30 x 16 x 21 cm arena with a black rubbish bag and clipped a 60W heat lamp onto the top lip of the arena. We roofed the arena with clear plastic clingfilm. We allowed the cold arena to reach 4.6℃ and the hot arena to reach 26.0℃.
Temperature switching and measurements
We took 20 milkweed bugs from the housing arena and placed 10 of them in the cold arena and 10 of them in the hot arena. We let them habituate for 30 minutes. We simultaneously switched the hot and cold arenas. One lab member removed the rubbish bag wrapping, the clingfilm roof, and unclipped the heat lamp of the hot arena while another removed the cold arena from the ice-packed box and removed its roof. We placed the hot arena into the ice-packed box and put shelled sunflower seeds in a petri dish and a cotton water source in the arena. At the same time, we clipped the heat lamp onto the cold arena, wrapped it with the rubbish bag, and roofed it with clear plastic clingfilm.
We recorded temperature and bug activity as defined by movement in both arenas simultaneously: in 15 second intervals for the first 120 seconds, in 30 second intervals until the 720 second mark, and in 60 second intervals until the 1500 second mark.
After the experiment had been run we placed the three arenas under the same conditions as the housing arena.
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