2,307 research outputs found
\u3ci\u3eTomicus Piniperda\u3c/i\u3e (Coleoptera: Scolytidae) Reproduction and Behavior on Scotch Pine Christmas Trees Taken Indoors
Tomicus piniperda, the pine shoot beetle, is an exotic insect that was first found in North America in 1992. A federal quarantine currently restricts movement of pine products, including Christmas trees, from infested to uninfested counties. We conducted a study to determine if T. piniperda would re- produce in Christmas trees that were cut and taken indoors during the Christmas season. Twelve Scotch pine, Pinus sylvestris, Christmas trees infested with overwintering T. piniperda beetles were cut in Indiana in early December 1993 and taken to Michigan. Four trees were dissected immediately, while the other 8 trees were taken indoors, placed in tree stands, and watered regularly. After 4 weeks indoors, 4 trees were dissected, and the other 4 were placed outdoors in Michigan for 7 weeks. Upon dissection, all overwintering sites occurred along the lower trunk within the first 40 em of the soil line; 81% were found within 10 em of the soil line. Adults collected from the 4 trees dissected in December produced viable progeny adults when placed on Scotch pine logs in the laboratory. Overwintering beetles became active and laid eggs in 4 of the 8 trees that had been taken indoors. All adults and progeny found in the 4 trees that had been placed outdoors for 7 weeks during cold January and February temperatures were dead. Overall, T. piniperda can become active and breed in Christmas trees that are cut and taken indoors in December. Tomicus piniperda survival in trees that are discarded outdoors at the end of the Christmas season will depend largely on the prevailing temperatures
Seasonal Shoot-Feeding by \u3ci\u3eTomicus Piniperda\u3c/i\u3e (Coleoptera: Scolytidae) in Michigan
Seasonal shoot-feeding by Tomicus piniperda (L.) was monitored at 2Â week intervals on 15 Scotch pine, Pinus sylvestris L., trees from 8 April through 16 November 1994 in southern Michigan. All shoots that showed evidence of T. piniperda attack were removed every two weeks. In 1994, initial spring flight of T. piniperda began on 22 March. At least two live T. piniperda adults were found on the 15 trees on each sampling date from 8 April through 1 November 1994. In addition, at least one freshly attacked, beetle- free shoot was found on each sampling date except for 1 November. The greatest numbers of newly attacked shoots, with or without adults present, were found from mid-June through mid-August. All adults found in April and May were likely parent adults, while those from June onward were primarily brood adults. Therefore, at all times of the year, live T. piniperda adults can be found on live pine trees, either feeding in the shoots or overwintering at the base of the trunk. Implications of these findings are provided in light of the US federal quarantine on T. piniperda
Disruptant Effects of 4-Allylanisole and Verbenone on \u3ci\u3eTomicus Piniperda\u3c/i\u3e (Coleoptera: Scolytidae) Response to Baited Traps and Logs
We assessed the inhibitory effects of the host compound 4-allylanisole (release rates = 1 and 2 mg/d in 1994, and 1 and 10 mg/d in 2001) on the response of the pine shoot beetle, Tomicus piniperda (L.), adults to funnel traps baited with the attractant host compound α-pinene (release rate = 150 mg/d) in two pine Christmas tree plantations in Michigan in spring 1994 and two other plantations in spring 2001. In three of the four plantations, all doses of 4- allylanisole significantly reduced T. piniperda attraction to α-pinene-baited traps by 46 to 76%. We also tested the inhibitory effect of the antiaggregation pheromone verbenone (release rates = 2 and 4 mg/d) on T. piniperda attack density on pine bolts (average bolt length was 62 cm and diameter was 19 cm) at three sites (two pine forest stands and one Christmas tree plantation) in Michigan in 1994. Verbenone significantly reduced T. piniperda attack density by 37 to 60% at the two pine stands, but not at the Christmas tree plantation
Duality symmetric massive type II theories in D=8 and D=6
We study compactification of massive type IIA supergravity in presence
of possible Ramond-Ramond (RR) background fluxes. The resulting theory in D=8
is shown to possess full T-duality symmetry similar to
the massless case. It is shown that elements of duality symmetry interpolate
between massive type IIA compactified on and ordinary type IIA
compactified on with RR 2-form flux. We also discuss relationship between
M-theory vacua and massive type IIA vacua. The D8-brane is found to correspond
to M-theory `pure gravity' solution which is a direct product of 7-dimensional
Minkowski space and a 4-dimensional instanton. We also construct D6-D8 bound
state which preserves 1/2 supersymmetries. We then discuss massive IIA
compactification on and point out that when all possible RR fluxes on
are turned on the six-dimensional theory appears to assume a nice SO(4,4)
invariant form.Comment: 19 pages, JHEP3, typos fixed, references added; v2: small correction
in eq.(5.3), published in JHE
Calabi-Yau Fourfolds with Flux and Supersymmetry Breaking
In Calabi-Yau fourfold compactifications of M-theory with flux, we
investigate the possibility of partial supersymmetry breaking in the
three-dimensional effective theory. To this end, we place the effective theory
in the framework of general N=2 gauged supergravities, in the special case
where only translational symmetries are gauged. This allows us to extract
supersymmetry-breaking conditions, and interpret them as conditions on the
4-form flux and Calabi-Yau geometry. For N=2 unbroken supersymmetry in three
dimensions we recover previously known results, and we find a new condition for
breaking supersymmetry from N=2 to N=1, i.e. from four to two supercharges. An
example of a Calabi-Yau hypersurface in a toric variety that satisfies this
condition is provided.Comment: 26 page
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