June 18, 2007
by: jovial_cynic
UPDATE: See the this post for a better identification about this ant.

Apparently, I can manipulate the colony into producing sexuals based on the amount of food I provide for them.

From the article:

1. In Elk Island National Park, Alberta, Canada, we studied the role of food supply in structuring a population of the ant Formica podzolica by examining the association between natural food levels and abundance, distribution and alate production of colonies, and comparing alate production of fed and unfed colonies.

2. Nest densities and reproductive output of colonies were greatest along forest edges, intermediate in grazed meadows and lowest in overgrazed meadows. These patterns among habitats were associated positively with natural food levels.

3. Colonies were dispersed uniformly on plots along forest edges, but dispersed either uniformly or randomly on plots in grazed and overgrazed meadows.
4. Females were larger than males, but size of neither males nor females differed significantly among habitats. Alate production was correlated positively with colony size.

5. Fed colonies in overgrazed meadows (the poorest habitat) produced significantly more sexuals within one reproductive cycle than those of unfed, control colonies, but not so compared to unfed colonies along forest edges (the best habitat).

6. We compare our experimental results with those of related studies of ants. In contrast to species that store food, we conclude that species storing relatively little food are more sensitive to changes in food supply, and respond to food addition in the short-term, even within one reproductive cycle.

Speaking of food, this article states the following:

Formica workers obtain much of their nutrition by tending aphids that feed on the shrubs growing on hummocks.

Hrm. This may get a little complex.

And then this article talks more about the food structure of my ants in great detail:

We investigated the spatial and temporal dynamics of pine (Pinus ponderosa) food webs that included the omnivorous ant, Formica podzolica, using direct observation and stable isotopes. Formica podzolica is a predator of herbivorous and predatory arthropods, and a mutualist with some aphids. Observations in 2001 of foragers showed that in early summer (June) ants fed upon equal parts non-mutualist herbivores (31% prey biomass), mutualist aphids (27%), and predators (42%); ant trophic position was thus between that of primary and secondary predator (trophic level = 3.4). In late summer (September), ant feeding remained relatively constant upon non-mutualist herbivores (53%) and mutualist aphids (43%), but ant feeding upon predators fell (4%), thus shifting ant trophic position to that of a primary predator (trophic level = 3.0). Feeding on honeydew increased from 25% of ants in early summer to 55% in late summer. By increasing the frequency of their interactions with mutualist aphids, ants maintained a constant supply of arthropod prey through the summer, despite a two-thirds decline in arthropod biomass in pine canopies.

Boy, oh boy.
np category: ants


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