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Neonicotinoid insecticides are widely used for controlling sucking pests, and sublethal effects can be expected in beneficial arthropods like natural enemies. Serangium japonicum is an important predator in many agricultural systems in China, and a potential biological control agent against Bemisia tabaci. We evaluated the toxicity of imidacloprid to S. japonicum and its impact on the functional response to B. tabaci eggs. S. japonicum adults exposed through contact to dried residues of imidacloprid at the recommended field rate on cotton against B. tabaci (4 g active ingredient per 100 l, i.e. 40 ppm [part per million]), and reduced rates (25, 20, 15 and 10 ppm) for 24 h showed high mortality rates. The mortality induced by a lowest rate, 5 ppm, was not significantly different than the control group and thus it was considered as a sublethal rate. The lethal rate 50 and hazard quotient (HQ) were estimated to be 11.54 ppm and 3.47 respectively, indicating a risk for S. japonicum in treated fields (HQ > 2). When exposed to dried residues of imidacloprid at the sublethal rate (5 ppm) on cotton leaves, functional response of S. japonicum to B. tabaci eggs was affected with an increase in handling time and a reduction in peak consumption of eggs. Imidacloprid residues also disturbed predator voracity, the number of B. tabaci eggs consumed on treated leaves being significantly lower than on untreated leaves. All effects disappeared within a few hours after transfer to untreated cotton leaves. Imidacloprid systemically applied at the recommended field rate (for cotton) showed no toxicity to S. japonicum, nor affected the functional response of the predator. Sublethal effects of imidacloprid on S. japonicum observed in our study likely negatively affect S. japonicum development and reproductive capacity and may ultimately reduce predator population growth. These results hint at the importance of assessing potential effects of imidacloprid on S. japonicum for developing effective integrated pest management programs of B. tabaci in China.

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1] We constrain structural features and shear-velocity structure of a low-velocity anomaly in the lower mantle beneath the Pacific (we term it the ''Pacific Anomaly'') on the basis of forward travel time and waveform modeling of the observed direct S, Sdiff, ScS, SKS, and SKKS phases sampling a great arc across the anomaly from eastern Eurasia to southern South America. After correction for the effects of earthquake mislocation and the seismic heterogeneities outside the Pacific Anomaly, seismic observations suggest that the Pacific Anomaly along the great arc consists of at least two separated portions with a 740-km-wide gap between them. The western portion of the anomaly is about 1050 km wide, extends at least 740 km above the core-mantle boundary (CMB), and exhibits a trapezoidal shape with lateral dimensions increasing slightly with depth. The velocity structure of the western portion varies from À3.0% at the top (740 km above the CMB) to À3.5% at 100 km above the CMB and an average shear-velocity reduction of À5% in the bottom 100 km of the mantle. The eastern portion of the anomaly reaches at least 340 km above the CMB beneath the mid-Pacific with an 1800-km-wide base and has a uniform velocity reduction of À3%. Waveform modeling further suggests a very low velocity layer with a shear-velocity reduction of À10% located at the edge of the western portion of the anomaly. Combining the latest results from others, we present a general picture of structural and velocity structures of the Pacific Anomaly. The structural and velocity features suggest that the anomaly represents a cluster of metastable thermo-chemical piles.Citation: He, Y., and L. Wen (2009), Structural features and shear-velocity structure of the ''Pacific Anomaly,''

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The Hengshan–Wutai–Fuping belt is located in the middle segment of the Trans-North China Orogen, a Palaeoproterozoic continental collisional belt along which the Eastern and Western blocks amalgamated to form the North China Craton. The belt consists of the medium- to high-grade Hengshan and Fuping gneiss complexes and the intervening low- to medium-grade Wutai granite–greenstone terrane, and most igneous rocks in the belt are calc-alkaline and have affinities to magmatic arcs. Previous tectonic models assumed that the Hengshan and Fuping gneiss assemblages were an older basement to the Wutai supracrustal rocks, but recent studies indicate that the three complexes constitute a single, long-lived Neoarchaean to Palaeoproterozoic magmatic arc where the Wutai Complex represents an upper crustal domain, whereas the Hengshan and Fuping gneisses represent the lower crustal components forming the root of the arc. The earliest arc-related magmatism in the belt occurred at 2560–2520 Ma, marked by the emplacement of the Wutai granitoids, which was followed by arc volcanism at 2530–2515 Ma, forming the Wutai greenstones. Extension driven by widespread arc volcanism led to the development of a back-arc basin or a marginal sea, which divided the belt into the Hengshan–Wutai island arc (Japan-type) and the Fuping relict arc. At 2520–2480 Ma, subduction beneath the Hengshan–Wutai island arc caused partial melting of the lower crust to form the Hengshan tonalitic–trondhjemitic–granodioritic (TTG) suites, whereas eastward-directed subduction of the marginal sea led to the reactivation of the Fuping relict arc, where the Fuping tonalitic–trondhjemitic–granodioritic suite was emplaced. In the period 2360–2000 Ma, sporadic phases of isolated granitoid magmatism occurred in the Hengshan–Wutai–Fuping region, forming 2360 Ma, c. 2250 Ma and 2000–2100 Ma granitoids in the Hengshan Complex, the c. 2100 Ma Wangjiahui and Dawaliang granites in the Wutai Complex, and the 2100–2000 Ma Nanying granitoids in the Fuping Complex. At c. 1920 Ma, the Hengshan–Wutai island arc underwent an extensional event, possibly due to the subduction of an oceanic ridge, leading to the emplacement of pre-tectonic gabbroic dykes that were subsequently metamorphosed, together with their host rocks, to form medium- to high-pressure granulites. At 1880–1820 Ma, the Hengshan–Wutai–Fuping arc system was juxtaposed, intensely deformed and metamorphosed during a major and regionally extensive orogenic event, the Lüliang Orogeny, which generated the Trans-North China Orogen through collision of the Eastern and Western blocks. The Hengshan–Wutai–Fuping belt was finally stabilized after emplacement of a mafic dyke swarm at 1780–1750 Ma.

[1] We determine the geographical boundary and average shear velocity structure of the Pacific Anomaly at the base of the mantle based on travel time analysis of ScSH-SH and ScS2 (ScSScS)-SS phases and waveform modeling results. We further constrain the detailed geometry of the northern Anomaly around (20 N, À170 E) and its transition to the surrounding high velocity region along three perpendicular cross sections on the basis of forward waveform modeling of the observed direct S and ScS phases. The observed differential travel-time residuals and waveform modeling results allow the whole geographic boundary of the Anomaly to be delineated and the area of the base of the Anomaly is estimated to be 1.9 Â 10 7 km 2 . The maximum shear velocity perturbation inside the Anomaly reaches À5% in the lowermost 500 km of the mantle. Waveform analysis suggests that the northern Anomaly reaches 450 km above the CMB with both steeply and shallowly dipping edges and its basal layer extends beneath the surrounding mantle with the degree of extension changing rapidly across a small distance. The inferred characteristics of the Anomaly support the previous suggestion that the Pacific Anomaly represents a chemical anomaly. However, unlike the inferred features of the African Anomaly pointing to an ancient compositionally distinct and geologically stable anomaly, the existence of several separated piles extending into the mid-lower mantle, the complex morphology of the piles with both steeply and shallowly dipping edges and the presence of many ultra-low velocity zones at its base suggest that the Pacific Anomaly likely possesses varying intrinsic compositions and exhibits complex interaction with the surrounding mantle.