Evaluation of plant constituents associated with pecan phylloxera gall formation.

The weights of pecanCarya illinoensis Koch galls caused by several species ofPhylloxera (Homoptera: Phylloxeridae) were negatively correlated with leaf and nut weights and nut production. Several allelochemicals (isoquercitrin, juglone, and 2 proanthocyanidins) were isolated from galls, and their antibiotic potentials were estimated, based on their toxicity to the bacteriaPseudomones maltophilia (Hugh et Ryschenkow). Pecan proanthocyanidins (condensed tannins) were characterized for the first time, and their stereochemistry was elucidated. The protein and total sugar contents of total leaves and leaf surface washings were determined. The leaf surface sugar content was very low, suggesting that the puncturing strategy of this insect may be for the purpose of finding sugars. The plant growth hormones gibberellic acid, zeatin, zeatin riboside, kinetin, indole acetic acid, and abscisic acid were found in pecan leaves, stems, and their galls. Gibberellic and abscisic acids were present in highest concentrations in all tissues, but lower in galled tissues, suggesting that increased biosynthesis by pecan plant growth regulators did not occur in response to insect attack.

Hydrocarbons from males, females, and larvae of pecan weevil: Curculio caryae (Horn).

As part of a program to identify as many as possible of the components of the pecan weevil, Curculio caryae (Horn), the hydrocarbons from males, females, and larvae were isolated by solvent extraction and column chromatography and subjected to gas lipuid chromatography-mass spectrometry analysis. n-Alkanes from C14-C32 in the larvae and unsaturated and branched chain hydrocarbons from C20-C32 in males and females were found. There are no significant differences between the hydrocarbons of the male and female pecan weevils.

Lipid composition of the pecan weevil,Curculio caryae (Horn).

The lipids of larvae, male adults, and female adults of the pecan weevil,Curculio caryae (Horn), were studied, and special attention was given the fatty acid composition. The larvae contained an unusually high amount of lipid material (40.6%), most of it concentrated in the neutral lipid fraction. Male and famale adults contained more conventional quantities, 5.8 and 8.2%, respectively. Oleic acid was the major fatty acid in the total and neutral lipids of all stages; linoleic acid was the most abundant in the phospholipid fractions.