INTRA AND INTERSPECIFIC COMPETITION BETWEEN LARVAE OF CERATITIS CAPITATA AND ANASTREPHA FRATERCULUS.

LIENDO, MARÍA C.; PARREÑO, MARÍA A.; VERA, MARÍA T.; SEGURA, DIEGO F.; CLADERA, JORGE L.

Congreso; VIII International Symposium on Fruit Flies of Economic Importance; 2010

Background: Ceratitis capitata and Anastrepha fraterculus are two major fruit pests in Argentina that overlap most of their ecological requirements, including host fruit species. Previous studies showed that it is common to find larvae of both species infesting one fruit, creating the needed conditions for the establishment of competitive interactions. The impact of competition will depend both on the density of larvae within a particular fruit and the relative abundance of each species, and could be asymmetrical between the two species. Here we compared the effects of competing with conspecific and heterospecific larvae both for A. fraterculus and C. capitata. Methods: Newly hatched larvae of both species were transferred into a container with a fixed amount of larval diet. Total density was set at the load capacity of each species and different proportions of larvae of the two species were then transferred (100% of C. capitata larvae; 25% of C. capitata and 75% of A. fraterculus; 50% of each species; etc.). As some larvae died after they had been transferred (during the initial 24-48hs) total density varied. We measured percentage of recovered pupae, pupae weight, larva-pupa developmental time, percentage of emergence and pupa-adult developmental time. Result: We found that when the relative density of A. fraterculus larvae increased, C. capitata pupae weight was reduced and the percentage of recovered pupae increased. In A. fraterculus, we found no effect on pupae weight and the percentage of recovered pupae, and these variables responded only to total density. For both species, we found no effect of total or relative densities on development times. Conclusion: Our results suggest that C. capitata larvae suffer more from sharing the resource with A. fraterculus larvae than with conspecific larvae. Conversely, A. fraterculus larvae experienced the same impact when they are sharing the host with conspecific or heterospecific larvae.