Abstract: Through establishing experimental and natural population life tables,and by using the index of population trend (I) and interference index of population control (IIPC),this paper evaluated 8 kinds of non-host plant ethanol extracts against experimental population of Plutella xylostella,and 3 kinds of these extracts and their mixture against Plutella xylostella natural population.The experimental population life table of DBM showed that the index of population trend (I) was 69.8964 in control,and decreased dramatically to 5.3702,4.4842,8.0945,(11.1382),6.8937,6.1609,5.5199 and 9.8052,respectively in treatments of Zanthoxylum bungeanum,Eucalyptus tereticornis,Nicotiana tabacum,Broussonetia papyrifera,Bauhinia variegata,Duranta repens,Euphorbia hirta and Camellia oleifera ethanol extracts,while the corresponding IIPC was 0.0768,0.0642,0.1158,0.1594,0.0986,0.0881,0.0790 and 0.1403,respectively.The natural population life tables of DBM showed that the index of population trend (I) was 21.6232 in control,and decreased dramatically to 5.1997,(7.4160),7.3644 and 3.1399,respectively in treatments of the ethanol extracts of E.tereticornis,N.tabacum,C.oleifera and their mixture,while the corresponding IIPC was 0.2405,0.3695,0.3549 and 0.1608,respectively.All of these indicated that the test plant extracts could interfere the development of P.xylostella population significantly,and had the potential as an effective measure for controlling insect pest.

Key words: Plant ethanol extracts, Plutella xylostella, Life table, Interference index of population control, Index of population trend