Six plant essential oils alone as repellent and fumigant, and in combination 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 funebris Endl., and Eucalyptus citriodora Hook. The repellency test indicated that L. bostrychophila adults were repelled by FIlter paper strips treated with six essential oils. Of these essential oils, the C. funebris oil was most effective followed by that of P. sylvestris, C. tangerina, C. bergamia, and E. citriodora. The average repellency of the C. aurantium oil against L. bostrychophila adults was significantly lower than other five test oils by day 14. These essential oils had a high level of toxicity in the fumigation assay against L. bostrychophila adults at both 10 and 20ppm. When combined with two controlled atmosphere treatments (12% CO2+9% O2, and 10% CO2+5% O2, balanced N2), the toxicity of plant oils was enhanced significantly.

The host plant-mediated impact of simulated acid rain (pH 3.0, 3.5, 4.0, 5.6, and 6.8) on the behaviour, development, and reproduction of carmine spider mite, Tetranychus cinnabarinus (Boisduvals), were evaluated at 25℃ in a series of laboratory trials. The results indicated that the adults of carmine spider mite prefer to aggregate on pH 4.0 acid rain-treated eggplant leaves. The developmental times of nymph, larva and the pre-oviposition period of the mite on kidney bean leaves were significantly affected by acid rain treatments. The developmental times for the immature stages ranged from 11.4 days on pH 4.0 acid rain-treated leaves to 12.7 days on other acid rain-treated leaves. The survival of immatures varied from 85.14% on pH 4.0 acid rain-treated leaves to 78.83% on deionized water-treated leaves (pH 6.8). The mites feeding on acid rain-treated leaves (pH 3.0-5.6) had significantly greater reproductivity and longevity than those feeding on deionized water-treated leaves. The average greatest reproductivity (74.6 eggs per female) and longest female longevity (8.9 days) were recorded on pH 4.0 acid rain-treated leaves. Accordingly, the intrinsic rate of increase (rm) for the mite on pH 4.0 acid rain-treated leaves was the highest. Jackknife estimates of rm varied from 0.201 on pH 4.0 acid rain-treated leaves to 0.158 on pH 5.6 acid rain-treated leaves. The results implied that the population growth of the mite were enhanced by application of acid rain (pH 3.0-5.6) on host plants.

The inhibition kinetics of dichlorvos on carboxylesterase and acetylcholinesterase (AChE) activity extracted from Liposcelis bostrychophila and L. entomophila (Psocoptera: Liposcelididae) were compared. The results showed that L. entomophila had significantly greater specific activity of carboxylesterase than L. bostrychophila (0.045 versus 0.012μmoles/mg/min). Moreover, the carboxylexterase of L. entomophila showed higher affinity (i.e. lower Km value) to the substrate 1-naphthyl acetate than L. bostrychophila (0.29 versus 0.67mM). The specific activity and affinity of AChE of the two species were not significantly different. The carboxylesterase of L. bostrychophila was more sensitive to the insecticide dichlorvos than that of L. entomophila. The I50s values of dichlorvos to carboxylesterase for L. bostrychophila and L. entomophila were 1.43 and 3.28μM, respectively, and to AChE were 324 and 612nM, respectively. Inhibition kinetics revealed that AChE from L. bostrychophila was 5.8-fold more sensitive to inhibition than AChE from L. entomophila.

Seasonal abundance of the Asian citrus psyllid, Diaphorina citri Kuwayama, was studied weekly in two orange jasmine [Murraya paniculata (L.) Jack] plots in southern Florida from October 1998 to October 1999. Psyllid populations occur throughout the season on orange jasmine in southern Florida. Population peaks were observed in October, November, and December in 1998, and May and August in 1999. Psyllid population levels were positively related to the availability of new shoot flushes which were in turn related to the weekly minimum temperature and rainfall. Natural enemies were not key factors in regulating populations during the study period. The populations of adult psyllids were also studied weekly on potted orange jasmine and grapefruit (Citrus paradise Macfadyen) plants from June 1999 to July 2000. The population levels of psyllid on both host plants were not significantly different and general population trends on the two hosts were similar over time. Continuous shoot flushes produced by orange jasmine could play an important role in maintaining high populations of this insect when new shoot flushes were not available in the commercial citrus groves.

Dispersion indices and related statistics of Asian citrus psyllid, Diaphorina citri Kuwayama, on orange jessamine [Murraya paniculata (L.) Jack] shoots in southern Florida from 1998 to 1999 were determined with 235 data sets and used to develop sampling plans. Three regression models, Taylor's power law, Iwao's patchiness regression, and k=c+dm [k=m2/(S2-m)] (where k is the parameter for the negative binomial distribution) were used to analyze the data. Taylor's power law (a= 0.3407