Rainfall increases gall morphological metrics in the Brazilian Cerrado

Abstract

The shape of the galls can be adjusted by factors such as natural enemies and climatic conditions to which the galls are subjected. Studies that evaluate the climatic regime as a possible driver of the morphology of galls are scarce and do not consider Neotropical systems. To fill this knowledge gap, this study evaluated the influence of seasonality on the morphology of Cecidomyiidae galls induced on Myrcia neoobscura (Myrtaceae) growing in the Cerrado of Bahia. A total of 270 galls were sampled during the dry and rainy seasons. The average monthly precipitation was obtained. The galls were refrigerated, weighed, and measured within 72 h of collection. The average weight of the galls ranged from 0.106 g to 0.780 g; while, the volume ranged from 35.07 mm³ to 726.70 mm³ and the surface area from 20.03 mm² to 719.57 mm². The average weight, volume, and surface area of galls were approximately 50% higher during the rainy season than during the dry season. These three variables were also positively related to average precipitation. These results support the hypothesis that seasonality may contribute to the observed variation in the final shape of galls on a local scale.

Keywords:
Cecidomyiidae; leaf gall; insect-plant interaction; Myrtaceae; Semiarid