INTERSPECIFIC VARIATION OF INSECT DEFOLIATION IN THREE SPECIES OF AVICENNIA AT CORINGA MANGROVES, INDIA.

Mangrove is a highly resilient ecosystem unique in harboring a diverse group of plants and animals with extreme salt tolerance capacity. In Indian scenario, 4461 km² area is under mangrove cover, amounting to 5% of the world's mangrove area. Coringa mangrove is situated in East Godavari district of Andhra Pradesh state in the east coast of India. Vast floral diversity of this mangrove supports large entomofaunal diversity. Damage of leaf photosynthetic area due to insect feeding is a major problem in this mangrove ecosystem. The present research focused on quantification of the damage of mangrove leaves due to insect feeding and measuring the extent of insect folivory between three species of Avicennia, a major floral component of Coringa mangrove. This study involved the application of a software-based digital image analysis to quantify the magnitude of insect defoliation. Three species of Avicennia, namely, Avicennia officinalis, Avicennia marina, and Avicennia alba were selected as target species due to their abundance in good numbers. The digital image of the collected leaf samples was created using desktop scanner, and the same was subjected to analysis. The result showed an overall range of 0.15-20.42% leaf area damage due to insect folivory in three species of Avicennia in two maturational stages of leaves, namely, young and matured leaves. The analysis showed significant variation in the magnitude of insect folivory in 2009, when compared between three species of Avicennia in the case of both young and matured leaves. However, in 2010, though in the case of young leaf samples, there is no significant variation in leaf area damage between three species; the matured leaves showed clear cut variation in damage extent. [ABSTRACT FROM AUTHOR]