THE RELATIONSHIP OF LAND COVER HETEROGENEITY AND INSECTICIDE USE WITH ARTHROPOD COMMUNITY STRUCTURE IN RICE AGROECOSYSTEMS

• Main Author: Utari Dewina, Restu
• Format: Theses
• Language: Indonesia
• Subjects: Ilmu hayati ; Biologi
• Online Access: https://digilib.itb.ac.id/gdl/view/70118
• Institution: Institut Teknologi Bandung

Rice agroecosystems are generally experiencing two kinds of environmental stress, i.e., a decrease in the heterogeneity of land vegetation types due to the development of settlements in the border zone and the excessive use of insecticides. Both of these are known to affect the structure of the arthropod community in the rice agroecosystem. The value of diversity, which describes the structure of the arthropod community, plays a vital role in the sustainability of the rice agroecosystem. The high diversity of arthropods indicates the existence of complex interaction processes that allow control of the population of arthropods that potentially become pests for rice plants. However, studies related to the effects of these two stresses in shaping the structure of arthropod communities have not been widely carried out, especially during the planting period in the rainy season. This study aims to analyze the relationship between land cover heterogeneity and insecticide use with taxonomic and functional diversity of arthropods in alpha, beta, and gamma dimensions. The study was conducted during the rainy season (October–March) on four rice agroecosystems in Bandung, West Java. Data was collected 30 and 50 days after planting (DAP). Arthropod sampling was carried out using a sweeping net, malaise trap, and pitfall trap methods. The arthropod samples were identified, and their taxonomic and functional diversity was calculated using the adequate number of taxonomic groups using the Shannon entropy formula (D). The results showed that arthropods' taxonomic and functional diversity were moderately correlated (r= 0.69). In general, land cover heterogeneity was positively correlated with the value of arthropod taxonomic and functional diversity, especially in the early vegetative phase of rice plants (30 DAP). In contrast, insecticides (g/m2) were negatively correlated with the value of arthropod diversity. The composition of arthropod species locally was relatively the same except in the rice agroecosystem with the lowest land cover heterogeneity and the highest use of insecticides. Based on the analysis of multiple linear regression equations, the coefficient value of the insecticide variable (taxonomy= -496.19, functional= -66.72) has more influence on the value of arthropod diversity than the variable coefficient of land cover heterogeneity (taxonomy= 4.41, functional= -0.15). Thereby, the results of this study support the understanding that increasing the heterogeneity of land cover types and decreasing the use of insecticides could be impactful efforts in maintaining arthropod diversity in rice agroecosystems. In addition, the use of insecticides is a crucial variable that significantly influences the structure of the arthropod community. Hence, its utilization needs to be considered and adequately monitored to maintain the diversity of arthropods that carry out ecosystem functions to support a sustainable agroecosystem.