1. Menu choices of a Mediterranean harvester ant Introduction Harvester ants carry seeds back to the nest, where the store them for the upcoming winter as food. Many studies for this behavior have been published, but there are very few references as to what type of different materials are transported back to the nest. Although there are descriptive records where harvester ants carried leaves, stems, petals, and pieces or whole insects (Fernández Escudero & Tinaut, 1993; Cerdá & Retana, 1994; Solida et al., 2011), no quantitative measurement for such data had been made.Introduction Results The results showed that harvester ants did not bring anything back to the nest during most of their activity period, while there was a gradual increase in the transportation of seeds (or fruits) from spring (May, June) to the summer and autumn (July - September). The small amounts of animal material transported increased slightly during the summer months, which was expected since that is the period with the most abundant terrestrial arthropods and hence increased probability of locating corpses of insects. Significant was also the increase of the transfer rate for other plant material (beside seeds) to the nest during the spring; an activity which is consistent with the observation of plant "clearing" which grow around the nest for the same period. Equally important was also the shift of materials transported between seeds and inorganic materials (soil, stones etc.) during October; the period during which the nuptial flight of most Messor species takes place.Results Methods With this as the basic question and by using 3 nests from different colonies of Messor merionalis André 1883, we recorded rates of different categories of materials (seeds, plant material, animal material, dirt, nothing) transferred back to the nest during the main foraging period for two years (April – November). Moreover, we divided the daily activity period into two parts - morning and afternoon (records taken at appr. 10am and 6pm).Methods Chris Georgiadis 1, Anastasios Legakis 2 1. Section of Zoology – Marine Biology, Department Biology, University of Athens, Greece, [cgeorgia@biol.uoa.gr] 2. Zoological Museum, University of Athens, Greece Seeds (or husks) Plant material (leaves, stems, etc)Animal material (insect legs, wings, etc)Dirt or pebblesNothing Monthly average material contribution for all items carried back to the nest for each year April MayJuneJuly August September NovemberOctober Harvester ants of the genus Messor are utilizing other food sources such as a piece of jelly bean (left) and leftovers of ice-cream (right) Monthly material contribution (%) for all items carried back to the nest during the morning (10am) and the evening (6pm) foraging period (irrespective of the year Seasonal Phenology In order for significant changes in the phenology of ant activity for each material type to be shown, we used a G-test for independence (goodness-of-fit test) (McDonald, 2009) between pairs of consecutive months. For those pairs that in both years there was a statistically significant difference to the previous, we suggested that there is a ‘seasonal’ shift for that material. Seasonal Phenology In order for significant changes in the phenology of ant activity for each material type to be shown, we used a G-test for independence (goodness-of-fit test) (McDonald, 2009) between pairs of consecutive months. For those pairs that in both years there was a statistically significant difference to the previous, we suggested that there is a ‘seasonal’ shift for that material. Incorporating the trend of shift for each type of material according to the ‘season’… Discussion So, harvester ants do not just eat seeds. They function within an opportunistic regime and readily utilize other food resources as these become available (Baroni- Urbani, 1987). Indeed, harvester ants are fit for seed gathering (Fernández Escudero & Tinaut, 1993). It is shown that most of the work done is performed away from the nest, thus workers come back empty. Finally, as winter approaches, more building material is moved around the nest ending during the first fortnight of October – time of Messor’s nuptial flight.Discussion So, harvester ants do not just eat seeds. They function within an opportunistic regime and readily utilize other food resources as these become available (Baroni- Urbani, 1987). Indeed, harvester ants are fit for seed gathering (Fernández Escudero & Tinaut, 1993). It is shown that most of the work done is performed away from the nest, thus workers come back empty. Finally, as winter approaches, more building material is moved around the nest ending during the first fortnight of October – time of Messor’s nuptial flight. References Baroni-Urbani C (1987) Comparative feeding strategies in two harvesting ants. In: Chemistry and biology of social insects (J Eder & H Rembold, eds.). Munich, Peperny 509-510 Cerdá X & Retana J (1994) Food exploitation patterns of two sympatric seed harvesting ants Messor bouvieri (Bond) and Messor capitatus (Latr) (Hym., Formicidae) from Spain. J. Appl. Entomol. 117: 268-277 Fernández Escudero I & Tinaut A (1993) Alimentación no granivora en Messor bouvieri Bondroit, 1918 y Messor barbarus L., 1767 (Hymenoptera: Formicidae). Bol. Asoc. Esp. Entomol. 17:247-254 McDonald JH (2009) Handbook of Biological Statistics (2nd ed.), Sparky House Publishing, Baltimore, Maryland, 319pp. Solida L, Celant A, Luiselli L, Grasso DA, Mori A & Fanfani A (2011) Competition for foraging resources and coexistence of two syntopic species of Messor harvester ants in Mediterranean grassland. Ecological Entomology 36: 409-416 Percentage (%) Seeds Dirt and soil Plant material Nothing Animal material