Effects of herbivore-induced rice volatiles on the host selection behavior of brown planthopper,Nilaparvata lugens

It has been suggested that herbivore would react to volatiles produced by herbivore infested plant due to potential change, either positive or negative, in the acceptability of the host plant. This hypothesis was tested for the brown planthopper (BPH) in the laboratory. Sixteen components of the headspace volatiles from rice seedlings with different treatments were collected with SPME and Tenax-TA trap and analyzed with GC and GC-MS. Significant differences in volatile emissions were observed for rice plants with different treatments. Undamaged control plants, mechanically damaged plants and the plants infested by BPH for 1 or 2 d emitted much lower amounts of volatiles compared to the plants infested by BPH for 3 or 5 d. The plants infested by BPH for 3 or 5 d emitted several volatiles that were not detected in undamaged control plants, mechanically damaged plants or the plants infested by BPH for 1 or 2 d. Spodoptera litura infested plants released much higher amounts of volatiles than those in all

Involvement of Jasmonate- signaling pathway in the herbivore-induced rice plant defense

The expression patterns of eight defense- related genes in the herbivore-infested and jasmonate- treated (jasmonic acid, JA and its derivative MeJA) rice leaves were analyzed using RT-PCR. The results showed that Spodoptera litura Fabricius (Lepidoptera: Noctuidae) herbi-vory induced the expression of lipoxygenase (LOX) and al-lene oxide synthase (AOS) genes that are involved in the jasmonate-signaling pathway. Moreover, S. litura damage resulted in the expression of farnesyl pyrophosphate syn-thase (FPS), Bowman-birk proteinase inhibitor (BBPI), phenylalanine ammonia-lyase (PAL) and other rice defense- related genes that were also induced by aqueous JA treat-ment or gaseous MeJA treatment. These indicated that in rice leaves, the JA-related signaling pathway was involved in the S. litura-induced chemical defense. Mechanical damage and brown planthopper (BPH), Nilaparvata lugens (St錶) (Homoptera: Delphacidae) damage induced the expression of LOX gene, but both treatments did not induce the expression of AOS gene. However, BPH damage induced the expression of acidic pathogen-related protein 1 (PR-1a), Chitinase (PR-3), and PAL genes, which is involved in the salicylate- signaling pathway. It was suggested that salicylate-related signaling pathway or other pathways, rather than jas-monate-signaling pathway was involved in the BPH-induced rice plant defense.

Effects of dietary nickel on apoptosis of hemocytes of Spodoptera litura (Fabricius) larvae

Effects of dietary nickel on apoptosis of hemocytes of the 6th instar larvae of Spodoptera litura Fabricius were evaluated using flow cytometry and Laser Scanning Confocal Microscopy (LSCM) by feeding S. litura larvae with artificial diets amended with different concentrations of nickel (1, 5, 10, 20 and 40 mg/kg) for 3 generations. Results showed that the hemocyte apoptosis rate of the 1st generation larvae increased with the increasing nickel concentrations in diet, and the apoptosis rate in the treatment with 40 mg/kg nickel was significantly higher than that in other treatments. In the 2nd generation, the highest hemocytes apoptosis rate was recorded in the treatment of the larvae exposed to 5 mg/kg nickel. The apoptosis rates in the larvae stressed by higher concentrations of nickel were lower than that in control. The apoptosis rates in the larvae exposed to nickel for 3 generations showed similar concentration-responses with that in the 2nd generation. However, the apoptosis rates in the larvae stressed with higher levels of nickel were all significantly inhibited in comparison with that in control. Therefore, effects of nickel stress on apoptosis of S. litura larvae were related with the nickel concentration in diets and the larval generations that were stressed by nickel.

Stable carbon isotope evidence for tracing the diet of the host Hepialus larva of Cordyceps sinensis in the Tibetan Plateau

Two types of Hepialus larvae with different diets were distinguished in the Sejila Mountain,Tibetan Plateau based on the stable carbon isotope data of the host Hepialus larva of Cordyceps sinensis and its closely adjacent tender plant roots and humus fractions.Type I is the larva chiefly fed by soil humus,and characterized by the δ 13C values of -22.6‰ to-23.4‰,and more than -23.4‰ in its heads.Type II is the larva chiefly fed by tender plant roots,and characterized by the δ 13C values of-24.6‰ to -27.6‰,and less than -24.6‰ in its heads.Our result has exceeded the traditional understanding that their food sources only come from the tender plant roots,and may provide evidence for choosing cheap and high-quality foods and further establishing artificial habitats in their large-scale reproduction.