Effect of Pine Forest Management on the Diversity of Ambrosia Beetles (Curculionidae: Platypodinae and Scolytinae) in East Java, Indonesia

Abstract

In Indonesia, Pinus merkusii, the Sumatran pine, is the most important forest tree in the industry. This study aimed to determine the effects of pine forest types and sites on the abundance of ambrosia beetles in four pine forest types and sites, i.e., the protected pine forest (PF1 & PF2), the pine forests-based agroforestry (PA1 & PA2), the tapped-pine forests (TP1 & TP2), and the non-tapped pine forests (NP1 & NP2). The environmental variables and the stand-ages were also studied related to the number of ambrosia beetle individuals and species. Twenty ethanol baited traps were installed to attract and collect the ambrosia beetles in each pine forest site. The descriptive analysis, the nested analysis of variance, and correlation analysis were applied to determine the differences in ambrosia beetle abundance between the pine forest sites, the relationship between the stand-age, humidity, elevation, and temperature to the number of individuals and species of ambrosia beetle, and species diversity of ambrosia beetles in each pine forest type. The Jaccard distance was calculated to investigate the dissimilarity between each pine forest site based on the ambrosia beetle species composition and abundance. The 999 ambrosia beetles (15 species) were reported in this study. Two were Platypodinae, and 13 were Scolytinae subfamilies. Xyleborinus andrewesi was the most abundant ambrosia beetle. The abundance of ambrosia beetles was significantly different between pine forest types (F = 89.23, p < 0.001). The population of ambrosia beetles was the highest in the protected pine forest, and the lowest one was identified in the non-tapped pine forest and the pine forest-based agroforestry. Based on the pine forest types, the highest number of ambrosia beetle species was in the protected pine forest (13 species), and the lowest one was in the pine forest-based agroforestry (7 species). The highest and the lowest numbers of ambrosia beetles were in the protected pine forest site 2 (11 species) and in the pine forest–based agroforestry site 2 & the non-tapped pine forest site 1 (3 species). The highest dissimilarity was shown by the highest distances between the pine forest-based agroforestry site 1 and the non-tapped pine forest site 1 based on the Jaccard distance. The stand-age, humidity, and temperature potentially effected the number of ambrosia beetle individuals and species. The elevation also indicated to influence the number of ambrosia beetle individuals however it isn’t happened on the number of ambrosia beetle species. This study contributes to identify the suitable pine forest types related to the ambrosia beetle management.