The main objective of this research is to investigate the influence of phorids, low humidity, and competition on the fitness of Solenopsis invicta Buren. It is hypothesized that S. invicta survival will be reduced under parasitoid pressure, low humidity, and competition from the southern fire ant, Solenopsis xyloni McCook. Currently, S. xyloni is the dominant fire ant in the semi-arid deserts of the southwestern United States. Solenopsis invicta was collected near College Station, TX and Temple, TX; S. xyloni was collected in Las Cruces, NM. All colonies of both species were polygynous. Colonies were connected to an arena where foragers were exposed to combinations of phorid flies, low humidity, and competition for one food source. Colonies were starved for 48 hours then allowed to forage for 72 hours. To evaluate competitive interactions, fire ants were counted and categorized on relative distance from the food source. At the end of the experiment food storage piles and the original food source were dried and weighed to evaluate foraging efficiency. Egg production was also calculated. From previous studies S. invicta was able to escape phorid attack by avoidance strategies and was able to overcome competition without phorid attack. This study evaluates the two influences in combination with low humidity as a possible advantage to S. xyloni.
Species 1: Hymenoptera Formicidae Solenopsis invicta (red imported fire ant)
Species 2: Hymenoptera Formicidae Solenopsis xyloni (southern fire ant)
Species 3: Diptera Phoridae Pseudacteon tricuspis (scuttle fly)
Keywords: biological control
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