We tested the hypothesis that maturing queens of the fire ant Solenopsis invicta produce more juvenile hormone (JH) after separation from their natal nest. Previous results indicated that mature reproductives produce an inhibitory pheromone that suppresses maturation in alates, but that external application of a JH analog counteracted this suppression and allowed the females to complete their maturation and produce eggs. To test whether JH levels increase with removal of inhibitory stimuli, the in vitro rate of JH biosynthesis by the CA of maturing females was measured using a radio-chemical assay for 20 days following separation from their natal nest. Biosynthesis rates were also measured in fully mature queens. Results indicate that JH rises during the first 5 days following separation from inhibitory stimuli then decreases to a level slightly above that found in alates prior to separation. We have studied the chemical composition of a queen attractant pheromone using a bioassay coupled with HPLC fractionation of queen extract to measure the attractiveness of isolated components. Results indicate there are at least 3 active components involved with attraction: one of medium polarity, probably invictolide; one of slight polarity, possibly alpha pyrone; and an unidentified non-polar component that must be combined with at least one of the other two to elicit attraction.
Species 1: Hymenoptera Formicidae Solenopsis invicta (red fire ants)
Keywords: juvenile hormone, attractant pheromone
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