【Objective】Red imported fire ant (RIFA) Solenopsis invicta Buren, a famous dangerous alien species in the world, was found to infest firstly at Wuchuan, Guangdong, China’s mainland in September 28, 2004. It distributed more than 30 counties and infested at 27 000 ha in late 2005. It had already caused serious damages to agriculture, human heath and ecosystems in these areas. Parameters related to the invasion of RIFA were investigated to explore its expansion pattern【.Method】In this study, most of 4 parameters of more than twenty invading cases were collected and analyzed, and the introducing time and expansion pattern of different cases were revealed according to the models that had been built up.【Result】 Models between acreage of quarantine area (Sq), acreage of area occupied by active mounds (Sf), active mounds quantity (Nm), density of active mounds at centre of infestation area (Dm) and duration from introduction time (T) were constructed, respectively, as follows: Sq=166384e0.5345T, Sf=28997e0.5784T, Nm=59.966e1.1756T and Dm=6.4533lnT - 0.9852. Speed of average location expansion of RIFA in south China was about 110-190 meters per year respectively by the models Sq=166384e0.5345T and Sf=28997e0.5784T. The method to determine the time when RIFA was introduced was built up according to the above models and data collected on the invading cases of RIFA. By analysis of the above models, RIFA was introduced and located the first time in China’s mainland about 10 years ago, and infested earlier in Shenzhen, Guangzhou and Wuchuan, then was introduced into other regions by transportation. Currently, the spatial distribution appeared in type of 2-2-2 obviously, including two large blocks, two small blocks and two skipping spots. One large block was composed of Zhujiang river delta, Huizhou and Heyuan, the other Wuchuan, Yangchun, Gaozhou, Dianbai and Maogang. Two littleblocks included Xinluo, Shanghang, Dapu and Cenxi, Luchuan, Beiliu, respectively. Nanning and Zhangjiajie were the two skipping spots in geography. According to COI gene diversity, introduction time and geographical distribution, RIFA was introduced through more than two ways, more than one spot and one time. The number of counties infested by RIFA in south China was significantly correlated to the duration after introduction, and the models were presented as Y1=2.6094X 1.0368 and Y2=4.1923X 0.9699. The number of counties infested in going-on decades was forecasted to be 43-58 in 2010, 120-150 in 2035, and the increasing speed was 3-4 counties per year. The expansion speed was shown to be 33.6 km per year and 98.3 km per year respectively by the methods of square root of acreage and beeline distance. The expansion speed was about 80 km per year.【Conclusion】The duration for invasion of RIFA into south China was about 10 year, and the districts infested were more than 30 late 2005. The local expansion speed was slown as 110-190 meters per year, but that speed at long distance was high, about 80 km per year.
Telenomus remus Nixon(Hymenoptera: Scelionidae) is an egg parasitoid of Noctuidae insects.The antennal sensory sensilla of female parasitoid were observed with scanning electron microscopy.Nine distinct types of sense receptors were observed,including sensillum basiconica,sensillum trichodea,sensillum trichodea curvata,sensillum styloconicum,sensillum campaniformium,fluted bent-tipped sensillum,pore-tipped ampullaceous sensillum,sensillum gemmiformium and sensillum chaeticum.Three forms of sensillum basiconica(SB) were found.SBⅠ were distributed at the end parts of scape that link the head and pedicel;SBⅢ were only found at the flagellum,and SBⅡ were always accompanied with the pore-tipped ampullaceous sensillum.Sensillum trichodea were distributed widely on the antenna with larger amount.However,the other seven sensilla were mainly distributed at the eighth to the eleventh fragments of antenna.
In this study preferences of the parasitoid Pachycrepoideus vindemmiae Rondani, to different ages of oriental fruit fly, Bactrocera dorsalis Hendel pupae, number of progenies, development time, adult longevity and sex ratio of the parasitoids have been studied. The results showed that P. vindemmiae parasitized pupae of all ages, and the rate of parasitism was high for 3 to 6 days-old pupae. The development time of parasitoid was significantly increased; in 3 to 6 days-old host compared with other age groups. The host mortality decreased with increasing host age. Male progeny developed faster than females, and older host pupae produced a higher proportion of males. Adult longevity of P. vindemmiae offspring were not affected by the age of the pupae. The results suggest that 3 to 6 days-old pupae of B. dorsalis are suitable host ages for P. vindemmiae and can be used for mass rearing P. vindemmiae under laboratory conditions for possible use in integrated pest management.
Abstract The effect of chemical insecticides on the structure and diversity of arthropod communities in various vegetable fields and the restoration of their biodiversity after stopping application of chemical insecticides were studied. The results showed that the effect of chemical insecticides on the arthropods in vegetable fields could be characterized the species structure, the diversity index and the evenness of species distribution. Components of arthpod species depended closely on the species number of insect pests, predatory natural enemies and spiders. Investigations showed that the numbers of species in the vegetable fields managed with chemical insecticides were obviously reduced, and their diversity indices were lower comparing with that without chemical insecticides. When the applications of chemical insecticides were stopped in vegetable fields, the index of population trend ( I ) of dominant insect pests decreased greatly, the control effect of natural enemies on major insect pests increased, and the diversity index of arthropod increased at the same time. Thus, limiting the application of chemical insecticides, resuming the environment of vegetable fields destroyed by using chemical insecticides, escalating the control ability of natural enemies on main insect pests will play an important role in the ecological control of insect pests in vegetable fields.
Based on the data of Bactrocera dorsalis(Hendel) adults quantity collected from the starfruit orchards in different locations of Guangdong Province in 2003-2004,and development durations of different stages at different constant temperatures in laboratory,the distribution dynamics of two peaks of adult including the first and the last peaks in a year.The methods of GIS and development-duration-model were used in the study.The results revealed that the first peaks of the pest adults appeared earlier when it progressed from southern part to northern part,and from western part to eastern part of Guangdong Province,and the last peaks of the adults appeared oppositely to the first peaks.The model for forecasting the peaks based on the development durations was constructed.The two methods of GIS and the development duration model could forecast the fruit fly peaks correctly at starfruit orhcards in Guangdong Province.
【Objective】From the bioguided fractionation of the ethanol extracts from the leaves of M. charantia, we obtained two most active compounds against the feeding of the diamondback moth, Plutella xylostella larvae. The antifeedant activity of momordicineⅠ and momordicineⅡ against the second and the third instar larvae of Plutella xylostella was tested using leaf discs of cabbage in the laboratory. 【Method】 A range of different solvents, including petroleum ether, ethyl acetate, n-butanol and water, were used to isolation ethanol extract from leaves of M. charantia. Bioassays were then conducted with these fractions to determine their impact on feeding of P. xylostella larvae, The ethyl acetate fractions had significantly impacts on feeding of P. xylostella larvae. The active fractions obtained by column chromatography were purified by high-performance liquid chromatography. Each compound isolated was identified by NMR, MS, and IR spectra.【Result】The results showed that Momordicin I and MomordicinⅡ had significant antifeedant activity on the larvae of P. xylostella, and MomordicinⅡ was more active than MomordicinⅠ. The concentrations for 50% antifeedant effects (AFC50 ) of MomordicinⅡ against the second and the third instar larvae of P. xylostella were 76.69 μg·ml-1 and 116.24 μg·ml-1 while that of MomordicinⅠ was 144.08 μg·ml-1and 168.42 μg·ml-1 respectively. In addition, MomordicinⅠand MomordicinⅡ had significant inhibitive effect on the rate of weight gain and survival of P. xylostella larvae. 【Conclusion】 Momordicin I and MomordicinⅡ had significant antifeedant activity and inhibitive development activity on the larvae of P. xylostella The elucidation of these chemicals is important not only for undestanding the insect-plant relatinships, but also for their potential in P. xylostella control.
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