Weaver ants regulate the rate of prey delivery during collective vertical transport

Burchill, A. T.; Pavlic, T. P.; Pratt, S. C.; Reid, C. R.

doi:10.1101/2022.06.22.497253

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bioRxiv · 10.1101/2022.06.22.497253

Weaver ants regulate the rate of prey delivery during collective vertical transport

Burchill, A. T.·Pavlic, T. P.·Pratt, S. C.·Reid, C. R.

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Abstract

The collective transport of massive food items by ant teams is a striking example of biological cooperation, but it remains unclear how these decentralized teams coordinate to overcome the various challenges associated with transport. Previous research has focused on transport across horizontal surfaces and very shallow inclines, disregarding the complexity of natural foraging environments. In the ant Oecophylla smaragdina, prey are routinely carried up tree trunks to arboreal nests. Using this species, we induce collective transport over a variety of angled surfaces with varying prey masses to investigate how ants respond to inclines. We found that weight and incline pose qualitatively different challenges during transport. Prey were carried over vertical inclines faster than across horizontal surfaces even though inclines were associated with longer routes and a higher probability of dropping the load. This additional speed is associated with more transporters being allocated to vertical loads and not from the persistence of individual ants. Ant teams also regulated a stable "prey delivery rate" (rate of return per transporter) across all treatments. Our proposed constrained optimization model explains these results: prey intake rate at the colony level is maximized when the allocation of transporters yields a similar prey delivery rate across loads.

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Burchill, A. T., Pavlic, T. P., Pratt, S. C., Reid, C. R.. 2022-06-26. Weaver ants regulate the rate of prey delivery during collective vertical transport. https://doi.org/10.1101/2022.06.22.497253

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