bicaule essential oil and four components against cigarette beetles and booklice was investigated with the method proposed by Zhang et al.
The results of contact toxicity of the essential oil and selected compounds against cigarette beetles and booklice are listed in Table 2.
Among the four selected compounds, (2E, 4E)-2,4-nonadienal showed the strongest toxicity against cigarette beetles ([LD.sub.50] = 2.31 [micro]g/adult) and booklice ([LD.sub.50] = 32.23 [micro]g/[cm.sup.2]).
All the containers housing booklice used in experiments were made escape proof with a coating of polytetrafluoroethylene (Sino-rich[R], Beijing Sino-rich Tech Co., Ltd., Xuanwu District, Beijing, China).
10 booklice were put on the middle of the filter paper.
lansium showed the best repellent activity than the other three, and it repelled over 90% booklice at 63.17, 12.63, and 2.53 nL/[cm.sup.2].
Contact toxicity of the oil against the booklice was measured as described by Zhao et al.
Precocene II ([LC.sub.50] = 30.4 [micro]g/[cm.sup.2]) exhibited stronger acute toxicity than precocene I ([LC.sub.50] = 64.0 [micro]g/[cm.sup.2]) against the booklice. Precocene II shows almost 2 times stronger toxicity than the oil while precocene I exhibits less toxicity than the oil.
houstonianum showed strong repellent activity (Class V) against the booklice at a concentration of 1.6 nL/[cm.sup.2] and higher concentration after 4 hr of exposure (Table 4).