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Results for “Engraving and Engravings”

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At least 37 records · Page 2Linked to original sources
PubMed2006

Antennally mediated negative feedback regulation of pheromone production in the pine engraver beetle, Ips pini.

Bark beetles use monoterpenoid aggregation pheromones to coordinate host colonization and mating. These chemical signals are produced de novo in midgut cells via the mevalonate pathway, and pheromone production may be regulated by a negative feedback system mediated through the antennae. In this study, we explored the effect of antennectomy on pheromone production and transcript levels of key mevalonate pathway genes in juvenile hormone III-treated male pine engraver beetles, Ips pini (Say). Antennectomized males produced significantly greater amounts of pheromone than podectomized males and those with intact antennae. Likewise, mRNA levels of three mevalonate pathway genes important in pheromone biosynthesis were measured by quantitative real-time PCR and found to be induced to a greater extent with antennectomy, suggesting a transcriptional regulation of pheromone production.

Animals↗
PubMed2006

Isolation, endocrine regulation and mRNA distribution of the 3-hydroxy-3-methylglutaryl coenzyme A synthase (HMG-S) gene from the pine engraver, Ips pini (Coleoptera: Scolytidae).

We isolated a full-length cDNA encoding 3-hydroxy-3-methylglutaryl coenzyme A synthase (HMG-S) from the pine engraver beetle, Ips pini (Say), and examined its genomic structure. The intron-less gene has a predicted 460 amino acid cytosolic protein product with 73% identity to HMG-S from Dendroctonus jeffreyi, and high identity (58-64%) with other insect HMG-Ss. Topically applied juvenile hormone (JH) III induced HMG-S mRNA levels up to 6.5-fold in both sexes, mostly in the anterior midgut, though there were differences between males and females in the timing, sensitivity to JH III dose and tissue distribution of HMG-S mRNA. These data further validate the coordinate regulation of mevalonate pathway genes for de novo isoprenoid pheromone production in bark beetles.

Amino Acid Sequence↗
PubMed2006

Effects of juvenile hormone on gene expression in the pheromone-producing midgut of the pine engraver beetle, Ips pini.

Juvenile hormone III (JH III) stimulates biosynthesis of the monoterpenoid aggregation pheromone component, ipsdienol, in the anterior midgut of the male pine engraver beetle, Ips pini (Say). To understand better the hormonal regulation of pheromone biosynthesis in this forest pest, and identify JH III-responsive genes, microarrays were prepared and hybridized to cDNA from midguts of JH III-treated beetles. Expression patterns were confirmed by quantitative real-time RT-PCR. JH III co-ordinately regulated mevalonate pathway genes and many other genes implicated in pheromone biosynthesis. Sex differences in basal levels of mevalonate pathway genes were consistent with their role in male-specific pheromone biosynthesis. This is the first microarray-based study of the developmental and hormonal regulation of insect pheromone biosynthesis.

Animals↗
PubMed2001

Effect of host tree seasonal phenology on substrate suitability for the pine engraver (Coleoptera: Scolytidae): implications for population dynamics and enemy free space.

This study evaluated the effects of seasonal phenology on the substrate quality of susceptible hosts to the pine engraver, Ips pini (Say). We also determined the effects of the duration and method of storage on host quality for purposes of laboratory rearing. Live red pine trees were felled at various times during the season, and I. pini adults from a laboratory colony were established on the logs. Subsamples of logs were stored for various intervals, and then provided to beetles. Subsamples of stored logs were waxed at both ends to prevent water loss before being submitted to the same assays. Suitability of red pine phloem tissue in susceptible hosts declined for I. pini throughout the growing season. As the season progressed, the number of beetle progeny that emerged from colonized hosts dropped substantially. This decline was associated with simultaneous reductions in phloem moisture content. Reduction in host suitability may partially offset any advantage I. pini may gain from colonizing trees after the major predators have become less abundant. Bark beetle brood production decreased significantly with length of storage, regardless of the month of tree felling or the method of storing. Implications for bark beetle population dynamics and laboratory rearing systems are discussed.

Animals↗