Comparison of pest occurrence and damage in Tainan No. 11 and Taichung Sen No. 10 rice varieties during the storage period

台南11號及台中秈10號是台灣稉稻與秈稻最主要之栽培品種。本研究特別選擇2016年一期此兩種品種，均有貯藏之彰化伸港鄉農會與鹿港鎮農會穀倉，進行兩種稻穀品種在貯藏期間之害蟲發生調查，並比較兩種稻穀於試驗前後之破損率差異，最後評估兩種稻穀之碾糙率，以瞭解害蟲於貯藏期間對兩種品種之為害差異。結果顯示兩處貯藏台中秈10號之穀倉在穀蠹（Rhyzopertha dominica）、米象（Sitophilus oryzae）及總害蟲發生數均高於台南11號稉稻，且於試驗後期有顯著差異，麥蛾（Sitotroga cerealella）則無顯著差異。兩處穀倉之穀蠹及米象約於貯藏第九個月開始大量發生，尤以秈稻更為明顯。兩種稻穀之蟲害破損率於試驗前無顯著差異，但於試驗一年後秈稻均顯著高於稉稻（p＜0.05）。貯藏後進行碾糙率測定，結果顯示兩處穀倉之稉稻碾糙率皆高於官定碾糙率，而秈稻碾糙率均低於官定碾糙率。在害蟲族群變化上，兩處穀倉之穀蠹及米象均於當年4至5月，穀倉溫度逐漸增高時大量發生，若能於此時期加強害蟲防治，將能大幅減少蟲害損失。在稻穀貯藏管理上，若貯藏品種為台中秈10號時，管理者更要加強蟲害管理，尤其要留意稻穀破損率，以免因破損率提升，使害蟲嚴重發生，導致最後碾糙率不足現象。 The major rice varieties of Japonica and Indica planted in Taiwan are Tainan No. 11 and Taichung Sen No. 10, respectively. Barn managers have observed that the occurrence of pests is higher in Indica rice than in Japonica rice, but an opposite trend has been revealed for the milling rate of brown rice. This study therefore aims to investigate pest occurrence in the two rice varieties produced from the first crop of 2016 during the storage period in the barns of Shengang and Lukang farmers' association in Changhua. To compare the damage caused by pests in two rice types after storage, we compared damage rates of the two rice varieties before and after testing and assessed the milling rate of two brown rice types. The result revealed that the numbers of Rhyzopertha dominica, Sitophilus oryzae, and the total of all storage of Tainan No. 11 were higher than those of Taichung Sen No. 10 in both barns. Significant differences for Rhyzopertha dominica and Sitophilus oryzae were observed before and after testing, but no significant difference was observed for Sitotroga cerealella. R. dominica and S. oryzae outbreaks started from the ninth month of storage in both barns, particularly for Indica rice. No significant difference was observed in the damage rates of the two rice types before storage, but the pest damage rate of Indica rice was higher than that of Japonica rice after storage (P ＜ 0.05). The milling rate of brown rice was estimated after storage. The official milling rate of brown rice was higher than that of brown rice for Japonica rice in both barns, but the opposite trend was found for Indica rice. From April to May, temperatures in the barns increased. More efforts for pest control may dramatically reduce the damage caused by pests. In the management of stored grain, managers should pay more attention to the damage rate of Taichung Sen No. 10 to prevent a large-scale pest problem and shortage of milled brown rice insufficient milling of brown rice