Insect Pests of Sal (Sharea robusta) and Planted Teak Forest (Tectona grandis) of Morang District, Eastern Nepal

Abstract

Forest of Nepal provides luxurious microclimatic gradients for various species of forest insect pests which are the most pervasive and important agents of forest degradation. The objective of the study was to record the insect pests of major timber trees species with their damage patterns and seasonal variation. Insects were recorded from 7 plots (10 m × 10 m) with 4 light traps along the north–south line transects within Kanepokhari Subdivision Forest Area on east west highway, eastern Nepal during pre-monsoon (MayJune)

and monsoon (July-August) season in 2021. Direct search method, sweeping, vegetation beating and light trap were used for the collection of the insects in both natural Sal forest and Teak plantation. All together 68 species were recorded including defoliator insects (47 species) were higher followed by woodborers (10 species), sap suckers (9 species), seed borer (1 species) and leaf roller (1 species) belonging to 25 families of 6 orders Coleoptera, Lepidoptera, Hemiptera, Orthoptera, Hymenoptera and Isoptera. This study shows that forest insect pest species diversity (2.93) and evenness (0.73) was slightly higher during monsoon season than pre-monsoon (H'- 2.76 and J- 0.69) season. The diversity of insect pest species was higher in natural Sal forests (pre-monsoon-2.81 and monsoon-3.07) than in Teak plantations (pre-monsoon-1.62 and monsoon-1.53). The findings of this study will provide the baseline information for the future insect pest studies and highlight the importance of immediate intervention by sustainable forest management activities.