| Arge similis(Vollenhoven) is an important pest in Shenzhen Wutongshan National Park. A. similis larvae feed on the plants of Ericaceae, and impaired the development and sight value of their host plants. The morphological, biological characteristics and life history of A. similis were studied in both the laboratory and field. Two life tables based on Spring and Summer nature populations were established. Host preference of both Arge similis female adults and their larvae were also investigated. Chemical composition of hemolymph from the larvae of A. similis was analyzed with High performance liquid chromatography-Mass spectrometer(HPLC-MC), and its feeding deterrence to predators was observed in laboratory. Antennal Sensilla and Ovipositor Morphology of the A.similis were observed with Eenvironment Scanning Electron Microscope(ESEM). The main results are as follows.1. Biological Characteristics and Life History of Arge similis(Vollenhoven)A. similis have seven generations per year in Shenzhen Wutong Mountain National Park,and it took 32-46 days to complete one generation. The activities of this pest could be observed during February-November, and over-wintered pupae began to emerge in the last-ten days of February, eggs were found in the early-mid days of March, the matural larvae of the 7th generation pupated in the last-ten days of November, and the overlapped generations appeared during April to September. A. similis preferred to lay eggs into the tissue of leaf edge at the back side. The larvae experienced five instars, the 1st and 2nd instars larvae fed in groups and started feeding dispersedly in 3rd instars. The old larvae pupated as a cocoon inside the soil at a depth of 3-5 cm to the surface or fallen leaves on the surface.2. Life tables of Arge similis(Vollenhoven) natural population Based on field investigation, two life tables of A. similis from Spring and Summer populations were established. The results showed that the index of population developmental trend of A. similis of the second generation in spring and the fifth generation in summer were22.13, 10.24, respectively. The most important factors influenced these two generation were non-emergenced of cocoon, and predation or others factors in the 1st instars larvae,respectively, and the exclusive indexes population control(EIPC) of those important factors were 1.24 and 1.44 correspondingly. Two important wasp species come from Eulophidae played an important role in influencing the population dynamic of A. similis, but their control efficiencies was changed with the seasons, which showed a lagging-effect.3. Oviposition and feeding preferences of Arge similis(Vollenhoven) to different plant species of Ericaceae.Three plant species of Ericaceae, Rhododendron pulchrum, R. indicum and R. simsii were chose to test the host preference of A. similis through choice and non-choice experiments.The results showed that the amounts of A. similes eggs on R.pulchrum were more than those on the other two host plants through non-choice experiment, however, there was no significant difference between R. indicum and R. simsii, and the eggs on three host plants could be ranked as R.pulchrum>R. simsii>R. indicum. Larvae of A. similis also showed strong feeding preference to R. pulchrum. Which was consistent with the field investigation that A.similes focused on the plant R. pulchrum.4. Chemical composition analysis of hemolymph from A. similis larvae with HPLC-MC and its feeding deterrence to predators Three chemical compounds,(C20H32O5), 2(C20H32O5) and(C20H32O4) were found in the hemolymph from A. similis larvae, they were suspected to come from the host plant. Bioassay was set up to test the deterrence of hemolymph of A. similis larvae to predators. Hemolymph from the matural larvae of A. similis showed strong feeding deterrence activity, the predator,Eocanthecona furcellata(Wolff) rejected the pests Tenebrio molitor L. coated with the A.similis larvae hemolymph. Though E. furcellata could feed on the larvae of Spodoptera litura(Fabricius) and Pieris rapae L. coated with the A. similis larvae hemolymph, it would take more time to probe the target preys.5. Antennal Sensilla and Ovipositor Morphology of the Arge similis(Vollenhoven)The typology, morphology, and distribution of antennal sensilla and the structure of ovipositor were described using scanning electron microscopy. The results showed that A.similis had clavate antennae and six morphologically different types of sensilla were observed on its antennae, including sensilla chaetica(types 1-3), sensilla trichodea(types 1-6), sensilla basiconica(types 1-4), sensilla coeloconica(types 1-2), basiconic capitate peg sensilla(types1-2), and B?hm’s bristles(Bb). Major differences were found between the sexes, in number,distribution, shape, structure, and size of the identified sensilla. A. similis has the binding pattern of ovipositor valvulae, sensory pore and two types of microtrichia were found on the ovipositor. Based on morphological evidence and research on Hymenoptera, these sensilla have an important role in finding host plants and sexual partners, and the structures of ovipositors increase our understanding of the behavior mechanism that how oviposition takes place. |
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