KEANEKARAGAMAN HYMENOPTERA PADA LANSKAP PERTANIAN RAWA PASANG SURUT DI KABUPATEN INDRAGIRI HILIR, PROVINSI RIAU

Zahlul, Ikhsan (2021) KEANEKARAGAMAN HYMENOPTERA PADA LANSKAP PERTANIAN RAWA PASANG SURUT DI KABUPATEN INDRAGIRI HILIR, PROVINSI RIAU. Doctoral thesis, Universitas Andalas.

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Abstract

Agricultural landscapes are a set of ecosystems that include agroecosystems and surrounding ecosystems consisting of natural habitats, roads, villages, and others (Forman and Godron, 1986; Duflot et al., 2017). Tidal swamp farming landscapes have unique characteristics different from other ecosystems, especially regarding their water conditions. Tidal swamps have water conditions that are affected by the tides of sea or river water. Tides can even cause flooding for 3-4 months in a year. Agricultural land can be inundated for several hours a day. Water conditions and landscape structures in the tidal swamp can affect the presence of insects in the agroecosystem. The Hymenoptera is a group insect with an important role as a parasitoid, predator, and pollinator in the agroecosystems. The study of the diversity of Hymenoptera in this study aims to: 1) Study the diversity of Hymenoptera in various tidal swamp landscape of Indragiri Hilir Regency, 2) Study the diversity of Hymenoptera parasitoids in tidal swamp rice and their correlation with structures of landscape, 3) Determine the superfamily that has the highest diversity in tidal swamp rice, 4) Study the diversity of the Chalcidoidea superfamily in tidal swamp rice and its correlation with structures of landscape, 5) Determine the components of the landscape and microclimate that most influence the diversity of Hymenoptera parasitoids and assess of their influence on the Chalcidoidea Superfamily in tidal swamp rice. The research was conducted in four landscapes of the tidal swamp in four sub-districts in Indragiri Hilir Regency. There is one simple landscape and three complex landscapes. Sample plots were determined using the line transect method in each landscape. Sampling was carried out using four tool traps: 1) swing nets; 2) yellow pan traps; 3) malaise traps; and 4) pitfall traps. Hymenoptera diversity analysis was carried out by calculating the Shannon-Wiener diversity index (H'), Margalef species richness index (D), Pielou species evenness index (J), Jaccard similarity index (Is), and Hymenoptera species richness estimation. The relationship between Hymenoptera parasitoid and environmental factors was seen using Pearson correlation analysis, principal component analysis, canonical correlation analysis, and multivariate regression analysis. The research has provided the results of landscape mapping at four locations (area ± 225 ha each) in the tidal swamp of Indragiri Hilir Regency. The simple landscape is dominated by rice and oil palm plantations, while the complex has more evenly distributed varieties of food crops, plantations, and horticulture. Besides, the complex landscape also has natural habitats that are more dominant than simple ones. The criteria for clustering of research location landscapes can be seen in Table 4.1. Air humidity on tidal swamp rice ranges from 55,0-71,5 %. Tidal swamp rice on a simple landscape has a lower average air humidity (60,67 %) than the complex landscape (69,08; 64,33; 66,83 %). The air temperature on tidal swamp rice ranges from 29,8-31,9 oC. Tidal swamp rice on a simple landscape has a higher average air temperature (31,55 oC) than the complex landscape (30,50; 31,00; 30,68 oC). Soil temperature on tidal swamp rice is between 27,3-30,1 oC. Tidal swamp rice on the simple landscape had a higher average soil temperature (29,47 oC) than the three complex landscapes (27,58; 28,28; 28,32 oC). Based on the analysis, there is a positive correlation and a negative correlation between the proportions of the landscape components with the microclimate in the tidal swamp rice of Indragiri Hilir Regency. This indicates a relationship between the proportions of the components of the landscape and the microclimate conditions in the tidal swamp. The meaning is that the proportion of landscape components in tidal marshlands can affect the micro-climate conditions of the agroecosystem. The Hymenoptera found in the tidal swamp landscape in Indragiri Hilir Regency were 27.649 individuals consisting of 11 superfamilies, 38 families, and 500 morphospecies. The high abundance of Hymenoptera in tidal swamp agroecosystems can be caused by natural plant vegetation around the agroecosystem. Natural habitats in agroecosystem landscapes can serve as shelter for Hymenoptera. Natural habitats can also supply alternative hosts or prey for Hymenoptera. Several studies have shown that landscapes with a high share of natural habitat can increase the diversity and abundance of natural enemies (Finke and Snyder, 2010). Thus, the natural habitat can be a source of natural enemies in the next planting season (Herlinda et al., 2011). Tidal swamp rice in complex landscapes has a higher diversity of Hymenoptera parasitoids than simple landscapes. This is because the complex landscape has many types of cultivated plants and natural habitats around the agricultural ecosystem so that there are always suitable sources of food and living habitat. Meanwhile, the simple landscape is dominated by agricultural plants that do not vary, coupled with the lack of natural plants around it. The type of agricultural landscape influences parasitoid diversity, i.e., agricultural landscapes with complex structures have a higher abundance, richness, and diversity of parasitoid species than landscapes with simpler structures (Bianchi et al., 2006). Another factor affecting the abundance of Hymenoptera parasitoids is the intensity of using synthetic materials by farmers. Farmers in the tidal swamp of Indragiri Hilir Regency are dominated by farmers who only apply pesticides when the level of damage is high. The minimal application of pesticides can increase the presence of Hymenoptera parasitoids. This is supported by the research results of Gnanakumar et al. (2012), who revealed that organic rice ecosystems have a higher abundance of Hymenoptera parasitoid than conventional rice ecosystems. Each component of the landscape correlates with the abundance of each family of Hymenoptera parasitoids. Natural habitat and air humidity are environmental factors that most predominantly affect the abundance of Hymenoptera parasitoids. The natural habitat in the tidal swamp landscape correlates with the abundance of the 11 family Hymenoptera parasitoid. Air humidity correlates with the abundance of 12 families of Hymenoptera parasitoids. The Chalcidoidea superfamily has the highest species diversity (4,05) on rice fields in tidal swamp landscapes, followed by Ichneumonoidea (4,02) and Platygastroidea (3,24) (Table 4.5). The Chalcidoidea superfamily has a high abundance of families and species. As many as 1.222 individuals consisting of 11 families, 20 subfamilies, 43 genera, and 96 species of Chalcidoidea were found on tidal swamp rice. The Tetrastichinae and Eulophinae subfamilies have the highest diversity index compared to other subfamilies. The results of the canonical correlation analysis showed that the abundance of Tetrastichinae and Eulophinae correlated with natural habitat and air humidity. The portion of natural habitat has a directly proportional relationship to the abundance of individual Tetrastichinae and Eulophinae. In contrast, air humidity has an inversely proportional relationship with the abundance of individual Tetrastichinae and Eulophinae.

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