Environmentally Sound Agro-Practice, Biodiversity and Indicator Species in Rice Paddies

2nd International Conference on Ecological, Environmental and Biological Sciences (EEBS'2012) Oct. 13-14, 2012 Bali (Indonesia) Environmentally Sound Agro-practice, Biodiversity and Indicator Species in Rice Paddies Takatoshi Ueno received growing attention because it plays a significant role in Abstract—Rice paddies occupy the largest cultivated area in agro-ecosystem function [2], [4]–[6]. agricultural land and provide the habitats for many organisms. Thus, Beneficial organisms such as natural enemies of pests and rice paddies are a key ecosystem in agricultural land that sustains a pollinators serve agro-ecosystem function [7]–[9]. In high level of agro-biodiversity. Natural enemies have an important agricultural fields where pesticide use is minimized, crop function for crop production as agents of ‘ecosystem services’ because they play a major role in suppressing pests. The diversity and production commonly depends on natural control provided by abundance of natural enemies can be a good index reflecting the natural enemies; they can have a great impact on pest ‘healthiness’ of agro-ecosystem services in rice paddies. In the present populations. Their importance is highlighted when biological study, a survey was made to investigate the abundance and control, i.e., active use of natural enemies, works well or when biodiversity of natural enemies in rice paddies where chemical inputs, the resurgence of pests takes place [3], [10]–[11]. i.e., insecticide use, were different. The reduction of chemical inputs Indiscriminate use of agro-chemicals such as insecticides led to an increase in species richness or diversity of natural enemies like parasitoids and spiders. Then, it was analyzed to explore suitable harms natural enemies and causes the loss of biodiversity of indicator species to assess environmental soundness of agricultural such beneficial organisms [10]–[11]. practice and biodiversity in rice paddies. Seven spotted ladybird The biodiversity of beneficial natural enemies may be a key beetle, Coccinella septempunctata, (Coleoptera: Coccinellidae) and a resource to improve the productivity and sustainability in web-constructing araneid spider, Neoscona adianta, (Araneae: agriculture [3], [6], [12]. Conservation of the biodiversity Araneidae) were among the commonest species of predators detected should then be an important approach for sustainable in paddy fields, and were tested to examine whether the density of the two could reflect the levels of chemical input and biodiversity. The agriculture. To do this, it is required to monitor and evaluate the density of the ladybird did not respond both to pesticide use and to diversity of beneficial organisms. The problem is that biodiversity, indicating that this species was not suitable as an monitoring the whole community or biodiversity is highly time indicator. In contrast, the araneid spider increased both with a and labor consuming. It is thus ideal to select indicator reduction of pesticide use and with an increase of biodiversity. organisms that directly or indirectly relate to the level of Neoscona adianta was hence a good candidate of natural enemies to biodiversity and to use them for monitoring the biodiversity of assess agricultural practice and biodiversity in rice paddies. Thus, it is possible to select species that are ideal bioindicators for monitoring beneficial and other neutral organisms [1], [4], [5]. both environmental soundness and biodiversity in agriculture. Being ‘ecological’ is on strong demand in agriculture Usefulness of indicator species in rice paddies is discussed. nowadays. Large-scale use of agro-chemicals cannot be an option of farming practices due to public concern for Keywords— Functional biodiversity, agro-ecosystem, pest environment and health issues. However, so called ecologically management, environmental monitoring. or environmentally friendly agriculture is mostly desired in terms of the production of safe food for humans with minimum I. INTRODUCTION use of agro-chemicals; its impact on conservation of GRICULTURAL LAND is the habitat for many biodiversity is often neglected. In Japan, eco-friendly A organisms, including pest, beneficial and neutral species, agriculture are widely applied in many crop production all of which exist together in both time and space. They systems, including rice paddies, but its consequent impact on constitute a ‘community’, which contains a wide variety of organisms is usually unclear [13]. species that differ in their functions, representing biological Environmentally sound agriculture should now be linked to diversity in agricultural land [1]–[3]. In other word, agricultural biodiversity in order to meet recently growing demand that land supports, at least in part, biological diversity. Biological organism communities in agriculture land should be conserved diversity (hereafter, biodiversity) in agricultural land has as possible though this idea has many conflicting aspects. By focusing the impact on biodiversity, environmentally sound agriculture would meet the demand by consumers (i.e. safe Takatoshi Ueno is with the Institute of Biological Control, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan (phone: food) as well as the demand from a point of view of sustainable +81-92-642-3036; fax: +81-92-642-3040; e-mail: [email protected]). production [13]. 20 2nd International Conference on Ecological, Environmental and Biological Sciences (EEBS'2012) Oct. 13-14, 2012 Bali (Indonesia) Rice is the primary food in Asia, where wet paddy pests. In many fields (but not all the fields), herbicides were cultivation is traditionally used for rice production. Rice applied once after transplanting rice. Around the flowering paddies occupy the largest cultivated area in Japan and other stage of rice, farmers applied Dinotefuran (a systemic Asian countries, which support one of the largest arthropod insecticide) twice to control leafhoppers, planthoppers and communities among agricultural systems [15], [16]. To practice green bugs but not all farmers applied such insecticides during environmentally sound rice production, the community of the growing stage of rice. Thus, rice paddies studied were beneficial natural enemies should be studied because without placed in three types; (1) organic fields (without any pesticide), this knowledge it is difficult to evaluate which management and (2) fields with insecticides only once during the seeding methods could be least influential to the biodiversity. Basic stage or (3) three times (once in seedling and twice during biology of beneficials in the community should also be growing stages). In my study, I mainly focused on maturing investigated [9], [14]. In addition, it is needed to establish stage of rice because all chemical inputs were terminated in this laboratory systems for testing the effects of agrochemicals like growth stage, which was suitable for the purpose of the study. insecticides and herbicides on beneficial insects [9], [14]. The maturing stage of Hinohikari was between September and Given that rice paddies provide habitats for hundreds of October. neutral and beneficial arthropod species [15], [16], all of these Arthropod natural enemies were sampled in 44 farmer’s organisms would be difficult to be involved in the fields. In 2008, general survey was first made to know the above-mentioned studies. Accordingly, it is crucial to select species composition of natural enemies found in the area of particular species or groups as indicator organisms for Nijyo-machi Town. For this purpose, sweeping with an insect extensive studies [1], [4], [13]. At least, candidate organisms net and visual collection were performed to obtain specimens, should be: widely distributed, commonly found, readily and the list of natural enemies was prepared. In 2009, data recognized or sampled, sensitive to agricultural practices and collection for analyzing biodiversity and exploring candidate easily reared in the laboratory [4], [5]. It is also ideal if indicator organism were made. To do this, inspection of the entire plant organisms reflect the biodiversity in agricultural land. was made to search natural enemies to obtain the data. In the present study, I focus only on arthropod natural Sampling was made by walking 5 m along 3 lows of rice plants. enemies, i.e., insects and spiders; birds, reptiles and amphibians Each field was sampled at two sites. This sampling was are not the targets of the study. This is because arthropods are repeated twice in different days for each field. The numbers of the major group of organisms recorded from rice paddies natural enemies were counted, and the species were recorded. [14]–[16]. Natural enemies are placed in three groups; When necessary, specimens were collected for exact predators, parasitoids and pathogens [8], [11], and the former identification to species. The results reported here were based two are among the arthropods. Parasitoids and predators are on the data collected from September to October, 2009. therefore the focus of my study here. I first examine the relationship between farming practices (pesticide use) and B. Data Analyses biodiversity of natural enemies, and, then, explore candidates as bioindicators in rice paddy ecosystems. Basing on the The data were analyzed with the aid of JMP (SAS, 2008). In results, I will discuss usefulness of bioindicators and my study, the diversity of natural enemies, i.e., parasitoids and conservation of beneficial natural enemies in the context of predators, was

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