Bock G. Chan

Condensed tannin, an antibiotic chemical from Gossypium hirsutum

Antibiotic activity against Heliothis virescens was found in flower buds of Gossypium hirsutum, experimental stock Texas 254. Relatively low antibiotic activity was found in hexane extract, high activity in methanolic extract and residue, and no activity in acetone and water extracts. A condensed tannin having a molecular weight of 4850 was isolated from methanolic extract by column chromatography on Sephadex G-25. It was the major antibiotic component, 3.4% of the dried flower bud. The condensed tannin at 0.2% in the diet retarded larval growth by 84%.

C-glycosylflavones from Zea mays that inhibit insect development.

Abstract A new C-glycosylflavone isolated from corn silk inhibits the growth and development of the corn earworm, Heliothis zea. This new compound was shown to be a 2″-O-α- l -rhamnosyl-6-C-(6-deoxy-xylo-hexos-4-ulosyl)luteolin. Also found co-occurring in corn silk were minor amounts of the corresponding 6-C-glycosylated analogs of chrysoeriol and apigenin.

p-vinylbenzeneboronic acid polymers for separation of vicinal diols

A relatively simple procedure was developed for preparing poly(p-vinylbenzeneboronic acid)-coated porous polystyrene beads which were shown to sorb and desorb vicinal diols reversibly through complex formation and to reject other hydroxy compounds. The complexing is highly pH dependent. By suitable adjustment of operating conditions, columns can be used for quantitative recovery of vicinal diols or can be used to separate mixtures of different vicinal diols chromatographically.

EFFECTS OF CYCLOPROPANOID AND CYCLOPROPENOID FATTY ACIDS ON GROWTH OF PINK BOLLWORM, BOLLWORM AND TOBACCO BUDWORM

The effects of dietary methyl esters of cyclopropanoid and cyclopropenoid fatty acids on the growth of larvae of the pink bollworm, Pectinophora gossypiella, the bollworm, Heliothis zea and the tobacco budworm, Heliothis virescens, was investigated. The major cotton cyclopropenoid, malvalate, had an ED50 of 0.28% for larvae of P. gossypiella, 0.64% for larvae of H. zea and 0.66% for larvae of H. virescens.

High-performance liquid chromatographic analysis of terpene aldehydes in cotton

Abstract A high-performance liquid chromatographic method has been developed for the analysis of terpene aldehydes in cotton plant material. This represents an improvement over previous methods, providing quantitative analysis for all the major terpene aldehydes using a minimum of plant material and preparation time.

Growth and hemolymph trehalose levels of Heliothis zea larvae fed diets containing various sugars

Abstract 1. 1. The amount of sugar required for growth of Heliothis zea larvae on a chemically defined diet was determined. 2. 2. Larvae grew well on fructose, galactose, sucrose, trehalose and raffinose diets but not on diets containing more than 0.5% glucose. 3. 3. A starch diet did not promote rapid larval growth. 4. 4. Hemolymph trehalose levels in 12-day-old larvae ranged from none to 45μmoles/ml. 5. 5. A method for analysis of hemolymph trehalose by gas chromatography is described.