Investigations on insecticidal efficacy of Bacillus thuringiensis preparations to the smaller tea tortrix, Adoxophyes sp. (Lepidoptera: Tortricidae).

• Main Authors: Yu-Chung Wang, 王宇仲
• Other Authors: Roger F. Hou
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/38168071426569591214

碩士 === 國立中興大學 === 昆蟲學系 === 93 === In this study, we used the preparations of two entomopathogenic bacteria, Bacillus thuringiensis subsp. aizawai (Bt-a) and B. thuringiensis subsp. kurstaki (Bt-k) based on international unit (IU) to examine the pathogenicity to the smaller tea tortrix, Adoxophyes sp. The LD50 values of B. thuringiensis subsp. aizawai and B. thuringiensis subsp. kurstaki to Adoxophyes sp. 4th instar larvae were 8.6 IU/ larva and 4.4 IU/ larva, respectively. The pathogenicity was not significantly different between two Bt preparations. When inoculated Adoxophyes sp. larvae with B. thuringiensis subsp. aizawai, the LT50 values increased with increasing larval instars. After exposing Bt-a sprays to different levels of solar radiation, the pathogenicity to Adoxophyes sp. larvae was decreased with increasing cumulative UV levels. Three simulated rainfall intensities were carried out for examining the wash-off of Bt sprays. The mortality of Adoxophyes sp. 4th instar larvae was decreased with increasing rainfall intensity. Addition of adjuvants to Bt preparations did not enhance adhesion on tea leaves at three rainfall intensities.. Based on pathogenic studies, it is suggested that B. thuringiensis preparations seem to be useful for biocontrol of the smaller tea tortrix.