利用燈光誘捕器調查各類穀倉之積穀害蟲種類與族群變化

Abstract

常見積穀害蟲具善飛及趨光性，常隱藏於穀倉、碾米倉或空倉死角，於新穀入倉貯藏或防治後再度入侵危害。台灣對稻穀及進口糙米倉之積穀害蟲主要利用農藥進行防治，本試驗利用燈光誘捕方式，評估在穀物貯藏期、碾米環境及空倉環境誘捕善飛害蟲之可行性。由稻穀倉之害蟲調查結果顯示，穀袋內取樣共得10種害蟲種類，主要害蟲為穀蠹（Rhyzopertha dominica）及米象（Sitophilus oryzae）；以燈光誘捕害蟲共調查得12種。進口糙米倉袋內採樣調查害蟲共得12種，以米象、粉斑螟蛾（Cadra cautella）、背圓粉扁蟲（Ahasverus advena）及角胸粉扁蟲（Cryptolestes pusillus）發生最多；以燈光誘捕蟲種類共得15種，碾米環境以燈光誘捕害蟲調查，害蟲種類更高達20種。在碾米環境的害蟲誘捕量甚至略高於鄰近進口糙米倉蟲數，且開放之碾米環境誘捕害蟲數遠高於封閉環境。當穀物清倉後，空倉內以燈光誘捕之害蟲數量明顯下降，但鄰近有稻穀倉時，誘捕害蟲量則會受稻穀倉害蟲族群影響而逐漸增高。由稻穀及進口糙米倉害蟲調查顯示，主要害蟲大部分為善飛害蟲，如穀蠹、麥蛾有極佳誘捕效果，但對米象及暹邏穀盜（Lophocateres pusillus）則效果不佳。因此，在稻穀倉、進口糙米倉、碾米環境及空倉環境適合以燈光誘捕方式降低害蟲密度，若應用於穀倉害蟲防治上，將可降低藥劑之使用頻率。 Most stored-product insects excel at flight, are phototactic, and frequently hide in the dead spaces of storage facilities, rice-milling areas or vacant warehouses, which provide the possibility to reinvade new stored products. In Taiwan, stored-product insects in warehouses storing local rice and imported brown rice are usually controlled with the application of chemicals. The aim of this work was to survey the variety and the population fluctuation of stored-product insects using light traps in various rice storage facilities, rice-milling areas, and vacant warehouses. The survey results showed that in rice storage facilities, 10 species were found by direct sampling in the bagged rice, and Rhyzopertha dominica and Sitophilus oryzae were found to be the dominant species. At the same time, 12 species were captured by light traps. In the imported brown rice warehouses, 12 species were found by direct sampling in the bagged rice, and there the dominant species were Cadra cautella, Ahasverus advena, and Cryptolestes pusillus. At the same time, 15 species were captured by light traps. Except for Sitophilus oryzae, the light traps showed very high efficacy of trapping other key insects. In rice-milling areas, 20 species were trapped by light traps. The numbers of trapped insects in the rice-milling areas were higher than the numbers of insects trapped in the nearby imported brown rice warehouses. The numbers of insects trapped in the open rice-milling areas were significantly higher than those trapped in the closed rice-milling areas. In a vacant storehouse, the numbers of trapped insects decreased significantly and were correlated with the insect densities of nearby storehouses with stored products. In conclusion, it should be noted that most of these key pests can fly and are attracted to light. The trapping efficacy for R. dominica and Sitotroga cerealella was much higher than for S. oryzae and Lophocateres pusillus. These results suggest that a light trap could be an effective device to lower the densities of insect pests in all types of rice storage facilities and rice-milling areas. It is certainly worth to be applied to control stored-product insects in order to reduce the use of chemical insecticides.