Komunitas Serangga Penyerbuk pada Habitat dan Jarak Berbeda dari Tepi Hutan Taman Nasional Gunung Halimun Salak

Abstract

Pollination service is one of many services that forest can provide for farming near to the forest which definitely harbors a high biodiversity of pollinator insects. Yet, forest degradation by farming activities is a threat for pollinator insect diversity, so there must some awareness to be given especially for the villagers about how important their forest is for their farms. The objectives of this research are: (1) to identify caisin’s (Brassica rapa L.) flower-visitor insects and to determine its function in its community, (2) to count abundance and species of pollinator insects and also to measure diversity index in distances from the forest, (3) to analyze spatial distribution of pollinator insects and its composition in every plot base on its similarity index, (4) to show the correlation of forest distance with the abundance and its diversity. Observation on caisin’s flower-visitor insects were carried out over 20 days period from 28 December 2006 – 16 January 2007, in margin forest of Gunung Halimun-Salak National Park, Sirnarasa Village, District of Sukabumi, Province of West Java. All insect visiting the flowers were counted by using fixed sampling method within 30 minutes observation period in each site that consisted of 20 flowering caisin plants. The forest distance factor giving the best fit was shown in a simple linear regression model on scatter plot graphic. This study showed that 1312 insects are found in caisin’s flower but only 747 insects or 56,94% of them are real pollinator insects which are representative of 32 pollinator species within 15 sites observation along the margin forest. Higher densities of pollinator insects are found near to forest’s margin than at greater distances from forest. The abundances of pollinator insects are usually high in open areas that provide fewer shade trees. Species diversity and abundance of pollinator insects were decreasing within distance from the forest despite there are many factors which may influence the abundance. The most influencing factor is the blossom cover of caisin in site observation that significantly has a positive correlation with flower visitation by insects. The other factors such as temperature and humidity did not significantly influence the flower visitation by insects