International Conference on Climate Change Impact and Adaptation (I3CIA-2013) Center for Climate Change and Sustainability Research (3CSR), Department of Civil Engineering DUET - Gazipur, Bangladesh 1 | Page IMPACT OF CLIMATE CHANGE ON RICE INSECT PESTS AND THEIR NATURAL ENEMIES Nur Ahmed 1 , Björn Holmquist 2 , Sultana Nasrin 2 , M Panna Ali 1 , M Nazmul Bari 1 , Mahfuj Ara Begum 1 , Nadira Afsana 1 and M Fazle Rabbi 1 ABSTRACT: Rice is one of the important staple foods for half of the world population particularly Asian countries for their livelihood, socio-economic and nutrition. Climatic factors e.g., temperature and humidity/ rainfall are the key factors for development of any rice insect pest and their natural enemies (friendly arthropods). Global warming is predicted to increase frequency of precipitation/rainfall, intensity of drought and solar-radiation/UV-B radiation which might affect the intensity and severity of rice pests in one hand, but also change in other friendly arthropods on the other hand. Climate change may influence the pest-plant and pest-natural enemy, finally ecological relationship, resulting in positive or negative influence on intensity and outbreak of pests. Climate change along with other intervention such as crop diversity, variety, irrigation, cropping intensity, fertilization/imbalance use and other management practices (e.g. indiscriminate use of insecticide) in rice production systems affect the intensity and severity of pests and natural enemies in the ecosystem. The present studies discuss the influence of climatic factors (temperature and rainfall) on yellow stem borer (YSB), brown planthopper (BPH), green leafhopper (GLH) and their natural enemies (spider, lady bird beetle, green mirid bug). Light trap and sweep net catches of arthropods from different rice habitats were used in this study. A time series (10 years data) analysis has been carried out using different mathematical models e.g. autoregressive integrated moving average (ARIMA) model and generalized linear model (GLM) to determine and predict the influence of temperature and rainfall on rice pests and their natural enemies in Bangladesh. There is a strong periodicity for YSB at 3 months and an equally strong periodicity at 6 months followed by a weaker periodicity at 12 months. BPH shows a strong periodicity at 6 months and a somewhat weaker periodicity at 3 months followed by a weaker periodicity at 12 months. For GLH there is a strong periodicity at 6 months and a somewhat weaker periodicity at 12 months followed by an even weaker periodicity at 3 months, especially valid for both methods of data collection (light trap and sweep-net data). Finally, for GMB there is a strong periodicity at 6 months and a somewhat weaker periodicity at 3 months followed by an even weaker periodicity at 4 months. This partially different pattern for GMB reflects the more irregular scenario for the outburst of abundances. There is a general increasing trend over the ten years seems to be present in the GLH. This increase was estimated to be 0.27 per year corresponding to 2.7 over a ten year period. This corresponds to that the abundance in 2005 is generally 15 times larger than in January 1996. For LBB, there is an increasing trend of log abundance of LBB over time and shows a strong periodicity at 3 months and a somewhat weaker periodicity at 4 months followed by an even weaker periodicity at about 6 months. For Spider there is a strong periodicity at 2.4 months and a somewhat weaker periodicity at 4 months followed by an even weaker periodicities at about 3 months and 6 months. There is an increasing trend of log abundance of Spiders over time. The relative growth of GLH is correlated with the relative growth of LBB but not of GLH and SPIDER. There seems to be a general trend of increase of GLH 10 to 15 times in population over 10 years. Results show an increase of maximum temperature of approximately 0.5 to 1°C over 10 years. The present results indicate abundances and growth rate of rice insect pests as well as their predators increases over time although only maximum temperature showing little increase but need to more long time data to conclude. Keywords:bph, glh, gmb, lbb, light trap, ecosystem, sweep-net, spider, ysb, rainfall, temperature 1 Introduction Agro-ecosystem is a multitrophic system with human interference. Crop is the centre of this ecosystem for farmer, and plant is the food basis or primary producer for an entire food web for an ecologist. Crop plant is very complex ecosystem, they competing with neighboring plants including weeds, and both are 1 Entomology Division, Bangladesh Rice Research Institute, Gazipur 1701 Bangladesh email: nurahmed31@gmail.com ; panna_ali@yahoo.com ; mn_bari@yahoo.com ; mab_bi@yahoo.com ; nadiraafsana@yahoo.com & rabbibrri@yahoo.com 2 Department of Statistics, Lund University, Lund, PO Box 743, SE-22007, Sweden email: Bjorn.Holmquist@stat.lu.se &Sultana.Nasrin@stat.lu.se