Larval age differences and competition between Drosophila aldrichi and D.buzzatii

Abstract. Competitive interactions among larvae of Drosophila species using the same habitat will usually involve individuals varying in age and size. Older, larger larvae might be expected to outcompete younger, smaller larvae. Newly hatched laryae of Drosophila aldrichi and D.buzzatii were placed on induced cactus necroses (simulating the natural habitat), either simultaneously, or with a 1 or 2 day difference in the time at which individuals of the other species were added. Evidence for competitive differences with larval age were found. In both species, body weight was significantly higher for those larvae added first than for later addition larvae, and a longer time to complete development was required for those larvae added 2 days later. However, pre‐adult viability of D.aldrichi was significantly higher for larvae started 1 or 2 days after larvae of D.buzzatii. For D.buzzatii, viability was lowest for larvae started simultaneously with D.aldrichi, but not different between those started either before or after D.aldrichi. Considering all three traits, no clear advantage for the early addition larvae was observed. Copyright © 1995, Wiley Blackwell. All rights reserved