Greene Michael J, Gordon Deborah M
Department of Biology, University of Colorado at Denver and Health Sciences Center, P.O. Box 173364, Campus Box 171, Denver, Colorado 80211, USA.
Am Nat. 2007 Dec;170(6):943-8. doi: 10.1086/522843.
Recruitment to food or nest sites is well known in ants; the recruiting ants lay a chemical trail that other ants follow to the target site, or they walk with other ants to the target site. Here we report that a different process determines foraging direction in the harvester ant Pogonomyrmex barbatus. Each day, the colony chooses from among up to eight distinct foraging trails; colonies use different trails on different days. Here we show that the patrollers regulate the direction taken by foragers each day by depositing Dufour's secretions onto a sector of the nest mound about 20 cm long and leading to the beginning of a foraging trail. The patrollers do not recruit foragers all the way to food sources, which may be up to 20 m away. Fewer foragers traveled along a trail if patrollers had no access to the sector of the nest mound leading to that trail. Adding Dufour's gland extract to patroller-free sectors of the nest mound rescued foraging in that direction, while poison gland extract did not. We also found that in the absence of patrollers, most foragers used the direction they had used on the previous day. Thus, the colony's 30-50 patrollers act as gatekeepers for thousands of foragers and choose a foraging direction, but they do not recruit and lead foragers all the way to a food source.
蚂蚁通过招募同伴前往食物或巢穴地点是广为人知的现象；招募者会留下一条化学踪迹，其他蚂蚁会沿着这条踪迹前往目标地点，或者它们会与其他蚂蚁一起走到目标地点。在此，我们报告一种不同的过程决定了收获蚁（Pogonomyrmex barbatus）的觅食方向。每天，蚁群会从多达八条不同的觅食路径中进行选择；蚁群在不同的日子使用不同的路径。我们在此表明，巡逻蚁通过将杜氏分泌物沉积在蚁丘上一个约20厘米长、通向一条觅食路径起点的区域，来调控觅食者每天所走的方向。巡逻蚁不会一路将觅食者招募到食物源，食物源可能在20米开外。如果巡逻蚁无法到达通向某条路径的蚁丘区域，沿着该路径行进的觅食者就会减少。在没有巡逻蚁的蚁丘区域添加杜氏腺提取物能恢复该方向的觅食行为，而毒腺提取物则不能。我们还发现，在没有巡逻蚁的情况下，大多数觅食者会沿用前一天走过的方向。因此，蚁群中的30 - 50只巡逻蚁充当着数千只觅食者的“守门人”，选择觅食方向，但它们不会一路招募并带领觅食者到达食物源。
