RAIDING IN NEWLY FOUNDED COLONIES OF SOLENOPSIS-INVICTA BUREN (HYMENOPTERA, FORMICIDAE)

Queens of Solenopsis invicta Buren, the red imported fire ant, that were collected following mating flights raised their first workers in the laboratory. Colony members were counted, queens were weighed, and all were marked with paint. Eighty-four colonies were randomly paired and the pairs were placed adjacent to one another and their behavior observed. At 4 d, 23 of the colonies had combined to form two-queen colonies, the other 19 formed single-queen combined colonies. At 60 d, 38 of the colonies had combined to form single-queen combined colonies. Queens that produced the greater number of brood survived in combined colonies. Colony raiding was the method observed for combining colonies. Supernumerary queens were eliminated by abandonment or attack by other queens or workers. Minims eliminated or abandoned the queens that produced fewer worker brood. Colony raiding may be an adaptive method of increasing colony size and vigor.