Weed Research (2016) 56, 14-21

J. Torra, V. Atanackovic, J.M. Blanco-Moreno, A. Royo-Esnal and P.R. Westerman (2016)
Effect of patch size on seed removal by harvester ants
Weed Research 56 (1), 14-21
Abstract: The harvester ant Messor barbarus can be responsible for high weed seed losses in dry land cereals in Spain. Because weeds occur in patches, harvester ants have to be able to find and exploit patches. However, seed patches can differ in size and may, therefore, differ in the probability of being discovered and exploited. Here, 90 patches varying in size from 0.25 to 9 m² were created in three 50 × 50 m subareas in a cereal field. Oat seeds were sown as weed seed surrogates in the patches at 2000 seeds m^-2. After 24 h, those remaining were collected and the exploitation rate (the percentage of seeds removed per patch discovered by ants) was estimated. Harvester ant nests and the location of the seed patches were georeferenced and used to estimate distances between them. The patch encounter rate (the proportion of patches discovered by the ants) decreased slightly, but significantly, with decreasing patch size, though not the exploitation rate, which was lowest in the smallest patches (78–94%) and highest in the largest (99–100%). Seed patches that were not found or partially exploited were mostly located in subareas with a lower ant nest density or a longer distance away from the nearest nest than seed patches that were fully exploited. The results of this study indicate that the interaction between the spatial distribution of ant nests and the patchy distribution of seeds can create opportunities for seeds to be subjected to lower levels of predation.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Joel Torra, Valentina Atanackovic, Paula R. Westerman, José Manuel Blanco-Moreno, Aritz Royo-Esnal

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Messor barbarus		Spain (continental)