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| Author(s): |
Eduardo Diehl Fleig
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2005-10-05 |
| Advisor: | Evoneo Berti Filho |
| Abstract | |
The aim of this work was to evaluate the aggressive behavior between workers from different nests of Linepithema humile Mayr, to determine the period of sexual production and the sexual ratio, to estimate the variation in the intranest population between summer and winter, and to investigate the reproductive biology, particularly the role of propagule sizes in the growth rates. For such, 26 nests collected in the Limeira population of the Argentine ant were set up in experimental nests in laboratory. The levels of aggressive behavior between workers from different nests (n = 11) were evaluated for three different periods during one year after nests collections. The intranest population was assessed by direct counting of total individuals in ten nests (five for each season). The growth rate was evaluated for different propagule sizes (10,50, 100, 150, 200 and 500 workers). The Limeira population structured as unicolonial, with absence of aggressive behavior to non nestmates workers. Workers from the Limeira population were highly aggressive to workers from another population (São Paulo). The population was strongly female-biased (2,4 : 1), with sexuals being produced during summer time. Worker number had a two fold reduction during winter compared to summer nests. The initial propagule size positively influenced the total brood production and negatively affected the per capita brood production. Per capita growth rates remained the same for all initial propagule sizes tested. Worker density reduction could be related to abiotic conditions during winter, especially relative humidity and rain falI. Several hypotheses are raised to explain the female-biased sexual ratio found in the studied population. This is the first record of unicoloniality in a Brazilian population of the Argentine ant. (AU) | |