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At least 289 records · Page 16Linked to original sources
PubMed2000

An asymmetric synthesis of (+)-grandisol, a constituent of the aggregation pheromone of the cotton boll weevil, via a kinetic resolution.

A novel approach to the asymmetric synthesis of (+)-grandisol, (1R, 2S)-isopropenyl-1-methylcyclobutaneethanol, involves the use of catalytic kinetic resolution of a primary allylic alcohol, [(1RS, 5SR)-5-methylbicyclo[3.2.0]hept-2-en-2-yl] methanol. The allylic alcohol is prepared in four steps from simple achiral materials involving the use of a modified Shapiro reaction. The resolved alcohol (95% ee) is then reduced in two steps to the corresponding methyl alkene, (1S,5R)-2,5-dimethylbicyclo[3.2.0]hept-2-ene. This alkene is converted to (+)-grandisol (95% ee), in three steps, by modified literature procedures.

Pheromones↗
PubMed2002

Pheromone-based trapping of West Indian sugarcane weevil in a sugarcane plantation.

Attraction of Metamasius hemipterus (Oliver) to gallon and bamboo traps baited with insecticide-treated sugarcane, the male-produced pheromone, 4-methyl-5-nonanol, and 2-methyl-4-heptanol is more efficient if ethyl acetate is added. The optimal traps are ground-level gallon traps baited with insecticide-laced sugarcane, pheromone, and ethyl acetate. Capture rates of ground-level gallon traps are doubled by placing an insecticide-laced pad under the trap, but significantly decreased by placing the trap on a stick above ground. The efficiency of ground-level gallon traps is the same as ground level ramp traps. Mass-trapping M. hemipterus in newly planted sugarcane using ground level bamboo traps baited with insecticide-laced sugarcane and pheromone over six months revealed populations were low for the first two months, became maximum at five months, and declined thereafter. Capture rates of traps bordering newly planted and mature sugarcane were not significantly different from capture rates of traps in the interior of the plots. Capture rates of bamboo traps containing only insecticide-laced sugarcane and deployed at 30 traps/ha averaged 6 weevils/trap/week compared with 66 weevils/trap/week for traps additionally containing pheromone lures and deployed at 5 traps/ha. Capture rates for bamboo traps baited with insecticide-laced sugarcane and pheromone and deployed at 10 and 15 traps/ha were 43 and 38 weevils/trap/week, respectively. Total captures were higher in those plots with a higher density of insecticide-laden sugarcane and pheromone baited traps, and the differences were approximately proportional to trap density in the range of 5-15 traps/ha. Capture rates of traps containing insecticide-laced sugarcane and pheromone were always higher than of traps containing only insecticide-laced sugarcane, but in the first two months after planting the differences were much greater than in months 3-6 after planting.

Animals↗
PubMed1997

Mitochondrial DNA sequence divergence in weevils of the Pissodes strobi species complex (Coleoptera:Curculionidae).

Mitochondrial DNA sequence divergence is unusually high between several species of the Pissodes strobi complex, in contrast to low allozyme and morphological divergences, and the ability to hybridize in the laboratory. We sequenced an 810 bp segment in seven individuals, representing four species in the P. strobi complex and one outgroup species, P. affinis Randall. The 810 bp segment covered the 3' half of the cytochrome oxidase subunit I (COI) gene. We also sequenced one specimen of P. strobi (Peck) over a 2301 bp region of mtDNA, extending from the 5' end of COI to the 3' end of COII. Uncorrected sequence divergences were below 1.1% among three specimens of P. schwarzi Hopkins, and between P. terminalis Hopping and P. nemorensis Germar. All other interspecific combinations in the P. strobi complex showed divergences of 6.0-7.5%. The outgroup species, P. affinis, had an average divergence of 12.8% from members of the P. strobi group. As in most other insects, A + T content in Pissodes mtDNA was high; transition:transversion ratio was high among lineages exhibiting low divergences, but declined with increasing sequence divergence; and inferred amino acid sequence divergences were low. The degree of sequence divergence differs markedly across different functional regions of the COI gene. The high mtDNA divergences within the P. strobi complex calculated from direct sequencing support earlier reports based on restriction site surveys; however, cladograms based on mtDNA sequence differ from those based on earlier work.

Amino Acids↗