D3186: Vegetation interferes with Cataglyphis sp. foraging, and these ants prefer open microhabitats

Desert Runner ants Cataglyphis urens use olfactory cues while foraging. We conducted 33 trials to determine if vegetation interfered with their foraging. In each trial, two dead crickets were placed 1m apart from each other and 1m upwind of a colony entrance. One cricket had dead vegetation (40 cm diameter ring) placed around it and the other was “open”. A 50 cm diameter circle in the sand was traced around each cricket. We observed the time for the first ant to touch the circle around each cricket, and the time it took for the first ant to touch each cricket. Ants touched the circle around the open cricket first 23 times versus 10 times for vegetated (two-tailed sign test, p = 0.024) and they touched the open cricket first 27 times versus 6 times for the vegetated cricket (two-tailed sign test, p = 0.00026). We deployed 47 pairs of pit traps in a sandy desert with patches of low shrubs. Traps of a pair were 1 m away from each other, one in open sand and the other in a shrub. Trap pairs were approximately 15 m apart. For 18 pairs of traps, there were more ants in open sand than vegetation, versus 6 pairs with more ants in vegetation (two-tailed Wilcoxon test for paired samples, p = 0.027). This study demonstrates that Desert Runner ants show higher activity levels in open sand microhabitats compared with vegetated microhabitats, and that vegetation interferes with the ants’ ability to detect their food.