Screening of germplasm of Gmelina arborea Linn. against infestation of Tingis beesoni Drake and subsequent impact on leaf anatomy

The present study assessed 42 germplasm of G. arborea by field evaluation, preference experiment as well as the biochemical parameters against its key pest insect T. beesoni, and clearly investigated the pest infestation damages in leaves through anatomical study. Secondary metabolites like phenols, flavanoids and terpenoids showed high concentration in clone SYG-11, which is categorized as a tolerant germplasm. The total phenols (r = -0.914) and total terpenoids (r = -0.848) showed strong negative correlation with the level of pest infestation (PI) and medium negative correlation with total flavonoids (r = -0.54). Consequently, secondary metabolites predicted significant variance (p < 0.05) to the pest incidence, whereas phenols, terpenoids and flavonoids showed strong negative correlation with preference experiment (r = -0.99292, r = -0.96665 and r = -0.84771) respectively. Results indicate that the high phenol content along with terpenoids and flavonoids tend to be the reason for high tolerance of clone SYG-11. In addition, the preference experiment through choice and no choice method confirmed the avoidance or less number of insects settling. The anatomical study of infested leaves illustrated the significant injuries in spongy parenchyma and the palisade parenchyma tissues. Tolerant/resistant quality of clones like SYG-11 against T. beesoni could be more helpful to reduce infestation and causality of G. arborea trees in plantation program.