Toxic effects of six plant oils alone and in combination with controlled atmosphere on Liposcelis bostrychophila (Psocoptera : Liposcelididae)

Six plant essential oils alone as repellent and fumigant, and in combinatio n with the controlled atmosphere against Liposcelis bostrychophila Badonnel were assessed in the laboratory. These essential oils were extracted from the leaves of six source plants: Citrus tangerina Tanaka, Citrus aurantium L., Citrus bergamia Risso et Poiteau, Pinus sylvestris L., Cupressus funebr is Endl., and Eucalyptus citriodora Hook. The repellency test indicated tha t L bostrychophila adults were repelled by filter paper strips treated with six essential oils. Of these essential oils, the C.funebris oil was most e ffective followed by that of F. sylvestris, C. tangerina, C. bergamia, and E. citriodora. The average repellency of the C. aurantium oil against L bos trychophila adults was significantly lower than other five test oils, by da y 14. These essential oils had a high level of toxicity in the fumigation a ssay against L. bostrychophila adults at both 10 and 20 ppm. When combined with two controlled atmosphere treatments (12%, CO2 + 9% O-2, and 10% CO2 5% O-2, balanced N-2), the toxicity of plant oils was enhanced significant ly.