Insect herbivory in Gondwana plants

Abstract

Plant–insect interaction is dominant in the extant flora and it is estimated that more than one million species of insects directly or indirectly survive on plants. In comparison, such association is limited in extinct flora, mainly due to problem in identifying structural features associated with the insect wronged plant fossils. Concerted efforts and comparative structures observed in extant flora have unfolded the mystery of insect herbivory in fossil plants. The study has helped to understand the feeding pattern and evolutionary features of insects during different time intervals and provide significant evidence to comprehend the co–evolution of plant and insect in the geologic past. Herbivorous insect wings discovered from different Gondwana successions of India belong to families and genera of Homoptera, Heteroptera, Mecoptera, Coleoptera and Blattoidea. The remains of Coleoptera and Mecoptera in all probability represent the earliest record in fossil flora. Insect herbivory is well recognized in Indian flora in the form of insect galls, chewing and eaten marks of leaf margin, disfigurement of lamina, egg–like pouches, trailing marks, mining activity, etc. The available records demonstrate the presence of well knit coalition of insect–plant interaction in Indian Gondwana successions. Diverse type of insect herbivory recovered in the Gondwana flora of India implies that insects used the plants for various purposes such as feeding, shelter and laying eggs for their development/ survival and the process has thus helped in the development and evolution of insects in consortium with plants.