Sexual dimorphism of galls Induced by Lopesia Mataybae (Diptera: Cecidomyiidae) on Matayba Guianensis (Sapindaceae).

Abstract

Usually one species of galling insect can induce just one gall morphotype on the host plant. The galling insect Lopesia mataybae (Diptera: Cecidomyiidae) induces two similar gall morphotypes on the leaflets of Matayba guianensis (Sapindaceae). However, these galls differ in thickness and size, a possible evidence of sexual dimorphism occurring in galls induced by a cecidomyiid. In the present study, the morphological, anatomical and histochemical attributes of male and female galls were examined and compared. Both gall morphotypes presented the galling insect in larva or pupa stages, and the emerged insect from different galls were sexually distinct. Galls induced by females were significantly bigger (height average = 4,67mm, S=0,43/ width average = 4,59mm, S=0,70) than male galls (height average = 2,95 mm, S=0,46/ width average = 2,34 mm, S=0,45), and the quantity and size of cell layers in female induced galls were higher. There were no differences in histochemical compounds detected in both male and female galls. The differences between the female and male galls found in this study may be due to differences in the life cycle of the insects, where female’s stimuli on the host plant lasts more than males, causing plant responses to be different and thus promote bigger galls for females.