Anatomical and physiological effects of Gynaikothrips uzeli Zimmerman (Thysanoptera:Phlaeothripidae) feeding on Ficus benjamina L. leaves

Abstract

Feeding by Gynaikothrips uzeli on Ficus benjamina causes extensive morphological changes (leaf curling and galling) to its leaves and reduced plant vigour. This in turn decreases the aesthetic horticultural appeal and economic value of the plant. In an effort to determine the extent of these changes, histological sections were made from mature healthy and galled leaves of F. benjamina. In addition, physiological parameters viz., leaf osmotic potential, stomatal conductance, chlorophyll content, leaf specific area and leaf dry matter content were assessed. Histological comparisons indicated that the lower epidermis, upper hypodermis, palisade and spongy mesophyll layers were significantly thinner in galled leaves than in healthy leaves. Additionally, stomatal density in galled leaves was approximately half that in healthy leaves. Leaf area and specific leaf area were significantly lower in infested leaves than in healthy leaves while osmotic potential was significantly more negative in infested than in healthy leaves. However, while levels of chlorophylls a and b decreased significantly in galled leaves compared to healthy leaves, the chlorophyll a/b ratio was not significantly different. The current study has identified several significant anatomical and physiological changes to leaves of F. benjamina infested with G. uzeli.