Morphometric traits and fluctuating asymmetry as indicators of larval stress in two tephritidae fruit flies.

GOANE, L.; LIENDO, M. C.; RUIZ, M. J.; JUÁREZ, M.L.; VALLADARES, G.; MILLA, F.; SEGURA, D.F.; VERA, M.T.

Congreso; 9th Meeting of the Tephritid Workers of the Western Hemisphere; 2016

Body size is largely recognized as a major fitness related trait which contributes to male successful mating, dispersal capacity, longevity and female fecundity; standing bigger individuals as better fitted. In holometabolous insects, adult body size largely depends on the conditions faced during larval development which is reflected in the reserves stored at pupal stage, often measured through the pupal weight. Previous studies in two important pests, Anastrepha fraterculus and Ceratitis capitata showed that overcrowding during larval development causes a reduction in pupal weight. Our objective was to find one adult morphometric traits which correlates with pupal weight in order to use it for further studies about the relevance of competition and larval rearing media as modulators of adult morphology. In addition, we examined fluctuating asymmetry (FA) of adults as a possible indicator of stress experienced during larval development. Pupae from different weights were obtained by manipulating egg densities. After adult emergence, we measured head width, thorax length, wing width, wing length, femur length and tibia length from the third leg. FA was evaluated in two bilateral traits (wings and legs) among adults obtained from pupae with different weight. Wing length was the variable which correlated the highest with pupal weight, suggesting it could act as a reliable indicator of stress by overcrowding, both for A. fraterculus and C. capitata. On the contrary, FA of wings was not consistently affected by pupal weight, showing that wing FA is not a good indicator of developmental instability inflicted by competition at the larval stage for both fruit flies species. Femur and tibia length were not suitable for the analysis due to high measurement error. We discuss the relevance of this approach to understand the impact of competition and host use during larval development on life history traits and henceforth in pest management.