The insecticidal activities of materials derived from the fruit of fennel, Foeniculum vulgare, against adults of Sitophilus oryzae, Callosobruchus chinensis and Lasioderma serricorne were examined using direct contact application and fumigation methods. The biologically active constituents of the Foeniculum fruits were characterized as the phenylpropenes (E)-anethole and estragole, and the monoterpene (+)-fenchone, by spectroscopic analysis. Responses varied with insect species, compound, dose and exposure time. In a filter paper diffusion test, estragole at 0.168 mg cm-2 caused 91% mortality to S oryzae adults within 1 day after treatment (DAT), whereas (+)-fenchone and (E)-anethole gave over 90% mortality at 2 and 4 DAT, respectively. Against C chinensis adults, all test compounds revealed potent insecticidal activities at 0.021 mg cm-2 at 2 DAT. Against L serricorne adults at 0.105 mg cm-2, (E)-anethole gave 100% mortality at 1 DAT, whereas 90 and 60% mortality at 4 DAT was achieved with estragole and (+)-fenchone, respectively. In a fumigation test, the compounds were much more effective against adults of S oryzae, C chinensis and L serricorne in closed cups than in open ones, indicating that the insecticidal activity of test compounds was largely attributable to fumigant action. As naturally occurring insect-control agents, the F vulgare fruit-derived materials described could be useful for managing field populations of S oryzae, C chinensis and L serricorne.
The ecdysis behavioral sequence in insects is a classic fixed action pattern (FAP) initiated by hormonal signaling. Ecdysis triggering hormones (ETHs) release the FAP through direct actions on the CNS. Here we present evidence implicating two groups of central ETH receptor (ETHR) neurons in scheduling the first two steps of the FAP: kinin (aka drosokinin, leucokinin) neurons regulate pre-ecdysis behavior and CAMB neurons (CCAP, AstCC, MIP, and Bursicon) initiate the switch to ecdysis behavior. Ablation of kinin neurons or altering levels of ETH receptor (ETHR) expression in these neurons modifies timing and intensity of pre-ecdysis behavior. Cell ablation or ETHR knockdown in CAMB neurons delays the switch to ecdysis, whereas overexpression of ETHR or expression of pertussis toxin in these neurons accelerates timing of the switch. Calcium dynamics in kinin neurons are temporally aligned with pre-ecdysis behavior, whereas activity of CAMB neurons coincides with the switch from pre-ecdysis to ecdysis behavior. Activation of CCAP or CAMB neurons through temperature-sensitive TRPM8 gating is sufficient to trigger ecdysis behavior. Our findings demonstrate that kinin and CAMB neurons are direct targets of ETH and play critical roles in scheduling successive behavioral steps in the ecdysis FAP. Moreover, temporal organization of the FAP is likely a function of ETH receptor density in target neurons.
Spin Hall effect, an electric generation of spin current, allows for efficient control of magnetization. Recent theory revealed that orbital Hall effect creates orbital current, which can be much larger than spin-Hall-induced spin current. However, orbital current cannot directly exert a torque on a ferromagnet, requiring a conversion process from orbital current to spin current. Here, we report two effective methods of the conversion through spin-orbit coupling engineering, which allows us to unambiguously demonstrate orbital-current-induced spin torque, or orbital Hall torque. We find that orbital Hall torque is greatly enhanced by introducing either a rare-earth ferromagnet Gd or a Pt interfacial layer with strong spin-orbit coupling in Cr/ferromagnet structures, indicating that the orbital current generated in Cr is efficiently converted into spin current in the Gd or Pt layer. Our results offer a pathway to utilize the orbital current to further enhance the magnetization switching efficiency in spin-orbit-torque-based spintronic devices.
Responses of forest ecosystems to increased atmospheric CO2 concentration have been studied in few free-air CO2 enrichment (FACE) experiments during last two decades. Most studies focused principally on the overstory trees with little attention given to understory vegetation. Despite its small contribution to total productivity of an ecosystem, understory vegetation plays an important role in predicting successional dynamics and future plant community composition. Thus, the response of understory vegetation in Pinus taeda plantation at the Duke Forest FACE site after 15-17 years of exposure to elevated CO2 , 6-13 of which with nitrogen (N) amendment, was examined. Aboveground biomass and density of the understory decreased across all treatments with increasing overstory leaf area index (LAI). However, the CO2 and N treatments had no effect on aboveground biomass, tree density, community composition, and the fraction of shade-tolerant species. The increases of overstory LAI (~28%) under elevated CO2 resulted in a reduction of light available to the understory (~18%) sufficient to nullify the expected growth-enhancing effect of elevated CO2 on understory vegetation.
Fluid clearance from the respiratory system during developmental transitions is critically important for achieving optimal gas exchange in animals. During insect development from embryo to adult, airway clearance occurs episodically each time the molt is completed by performance of the ecdysis sequence, coordinated by a peptide-signaling cascade initiated by ecdysis-triggering hormone (ETH). We find that the neuropeptide Kinin (also known as Drosokinin or Leukokinin) is required for normal respiratory fluid clearance or "tracheal air-filling" in larvae. Disruption of Kinin signaling leads to defective air-filling during all larval stages. Such defects are observed upon ablation or electrical silencing of neurons, as well as RNA silencing of the Kinin gene or the ETH receptor in neurons, indicating that ETH targets Kinin neurons to promote tracheal air-filling. A Kinin receptor mutant fly line ( ) also exhibits tracheal air-filling defects in all larval stages. Targeted Kinin receptor silencing in tracheal epithelial cells using or () drivers compromises tracheal air-filling. On the other hand, promotion of Kinin signaling in vivo through peptide injection or neuron activation through TrpA1 (dTrpA1) expression induces premature tracheal collapse and air-filling. Moreover, direct exposure of tracheal epithelial cells in vitro to Kinin leads to calcium mobilization in tracheal epithelial cells. Our findings strongly implicate the neuropeptide Kinin as an important regulator of airway clearance via intracellular calcium mobilization in tracheal epithelial cells of .
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