Paul A. Hedin

Constituents of the cotton bud

Abstract The investigation of the alcohol fraction of the essential oil of cotton ( Gossypium hirsutum L. var. Deltapine Smoothleaf) with an integrated gas-liquid chromatography-mass spectrometry system resulted in the identification of 17 additional alcohols and β-ionone. Tentative assignments were made for 4 other alcohols. None of these has previously been reported in cotton.

Biosynthesis of grandlure, the pheromone of the boll weevil, Anthonomus grandis, from acetate, mevalonate, and glucose.

Abstract The steam-distilled faeces of adult male boll weevils, Anthonomus grandis , that had been injected with acetate-1 14 C, acetate-2 14 C, mevalonic acid-2 14 C, or glucose 14 C(U) showed by column and gas chromatography that approximately 0·02 per cent of the administered radioactivity was incorporated into the volatile fraction. Also, 4 components of the pheromone comprised 57 to 80 per cent of the radioactivity of the volatiles but only 39 per cent of the total content of volatiles. Thus, evidence was obtained for de novo synthesis of the components. Although the boll weevil is essentially an obligate insect of cotton, this insect does not appear to require any specific component in cotton for biosynthesis of the pheromone.

Identification of Male Pecan Weevil Pheromone

The pecan weevil, Curculio caryae is a serious economic pest of pecans (Caryae illinoensis). In late summer, the weevil attacks maturing nuts and damages them when making feeding and/or oviposition punctures. The larvae leave the nut and burrow into the soil, remaining there for two to three years before emerging as adults to commence another cycle. This present work has resulted in the identification of the male pecan weevil pheromone as a mixture of four components; I as both the cis and trans isomers of 2-propenyl-1-methyl-cyclobutaneethanol [also identified as (1R,2S)−(+ and −)-grandisol], II [(Z)-3,3-dimethylcyclohexane-Δ1,β-ethanol], III [(Z)-3,3-dimethylcyclohexane-Δ1,α-acetaldehyde], and IV [(E)-3,3-dimethylcyclohexane-Δ1,α-acetaldehyde]. They are synthesized by the male pecan weevil, but not by the female, in the ratio 7:16:3:3 of I, II, III, and IV, respectively. These same compounds were earlier identified as the pheromone of the male boll weevil, Anthonomus grandis (Boh.), in which they were isolated from frass in the ratio 6:6:1.5:1.5. However, only the (+) isomer of grandisol was synthesized by male boll weevil. In laboratory tests, 80% of female pecan weevils were attracted to a synthetic formulation based on the ratio found in male pecan weevils, while only 28% of the females were attracted to a synthetic formulation based on the ratio found in boll weevil frass. The attraction of males to these synthetic formulations was minimal (14, 4, and 2%, respectively). Live males and their extracts were also attractive to females, but males did not respond to male or females. Preliminary field tests demonstrated that females were attracted to males and the synthetic pecan weevil formulation, but not to the synthetic boll weevil formulation.

Cyanidin-3-β-glucoside, a newly recognized basis for resistance in cotton to the tobacco budwormheliothis virescens (Fab.) (lepidoptera: Noctuidae)

Cyanidin-3-β-glucoside was shown to be an important factor of resistance in cottonGossypium hirsutum L. leaves to the tobacco budwormHeliothis virescens (Fab.). This provides a potential basis for achieving insect resistance in non-glanded cotton and other crops infested byHeliothis.

Isolation of the insect paralyzing agent coniine fromSarracenia flava

As part of a study to clarify the relationship between insects and the insectivorous plantSarracenia flava, we have observed the presence of the paralyzing agent coniine in the volatile constituents. Fire ants have been used as the test organism in bioassay studies for paralyzing activity.

Identification and field evaluation of the compounds comprising the sex pheromone of the female boll weevil

The terpenoid compounds (+)-cis-2-isopropenyl-1-methylcyclo-butaneethanol (I), (Z)-3,3-dimethyl-A-cyclohexaneethanol (II), and β-caryophyllene were isolated from frass of the female boll weevil (Anthonomus grandis Boheman). In laboratory bioassays, a mixture of these components attracted primarily males, whereas the male pheromone, grandlure, attracted primarily females. The addition to the cotton bud hydrocarbons, α-pinene, myrcene, andl-lim-nene, improved the response by males so that the potency of the mixture was comparable to that of grandlure for females. In field tests, I + II + hydrocarbons attracted both sexes, but grandlure alone and grandlure + hydrocarbons were more effective.

Constituents of marsh grass: Survey of the essential oils in Juncus roemerianus

Abstract The essential oil of Juncus roemerianus was isolated by steam distillation with a yield of 0·01 % of the fresh grass. Analysis by combined GLC-MS gave evidence for the presence of 78 compounds. They included 13 benzene derivatives, 11 polycyclic (mostly naphthalene type) compounds, 8 cyclohexyl compounds, 32 acyclic compounds, 9 terpenoids, and 6 furan derivatives. In total, these compounds accounted for 46·6% of the oil. Due to the presence of tetrachlorobenzene and benzyl cyanide, other halogenated compounds and alkaloids can be anticipated.

Hemicellulose is an important leaf-feeding resistance factor in corn to the fall armyworm

The fall armyworm,Spodoptera frugiperda (J. E. Smith), (FAW) is a major pest of corn,Zea mays L., in the southeastern United States. The damage to pretassel corn is caused by larvae feeding primarily on immature inner whorls. In this study, resistant lines were found to contain more crude fiber in whorls, mostly hemicellulose and cellulose. While hemicellulose, chiefly an arabinoxylan, was higher in resistant (R) lines than in susceptible (S) lines, the distribution of constituent neutral sugars was very similar in the lines. Both lines also containedp-coumaric and ferulic acids. These phenolic acids are known to occur both in the free state and in the cell wall as complexes bound by ester linkages to the arabinose moiety of the arabinoxylan.13C NMR data showed that the intensity of the carbonyl carbon (184 ppm) in resistant hemicellulose was stronger, indicating a greater degree of cross-linking. Thus, resistant hemicellulose is both structurally different from susceptible hemicellulose and present in greater quantities. In two of three laboratory dietary tests, FAW larval weight gains were significantly higher on diets with (S) hemicellulose incorporated at the same level as (R) hemicellulose. Therefore, resistance to the FAW appears to be correlated with both a greater amount and a higher degree of cross-linking of the hemicellulose of (R) lines.

Roles of amino acids, protein, and fiber in leaf-feeding resistance of corn to the fall armyworm

The free amino acids have been shown by isolational work and choice bioassays to be more important than all other factors evaluated in defining leaf-feeding resistance of corn (Zea mays L.) to fall armyworm (FAW) [(Spodoptera frugiperda J.E. Smith)] larvae. 6-MBOA (6-methoxybenzoxazolinone) and maysin, toxins present in corn, were shown not to be significant factors for leaf-feeding resistance to first-instar FAW larvae because of their low concentrations in the whorl. Amino acid analysis showed that while the ratios of the essential amino acids in susceptible (S) and resistant (R) lines were similar, there were differences in the nonessential amino acids, particularly aspartic acid, which was higher in R lines. Also, the ratio of essential amino acids to nonessential amino acids was important, being too low in expressed whorl leaf juice (obtained from V8–V10 growth stage plants) to support larval growth, although juice was stimulatory in choice tests. The total protein content of whorls in S lines was about 15% higher than in R lines, but the significance of this difference is uncertain, because nutritional tests showed that larval growth increased with total protein only up to 12% protein. Sugars were only slightly stimulatory. Thus, the amino acids along with higher hemicellulose content of R lines, established by us earlier, appear to explain much of the basis of resistance in corn to larval leaf-feeding of the FAW.

Volatile constituents of the boll weevil

Abstract When the distillable oil from adult boll weevils, Anthonomus grandis , of both sexes was investigated with an integrated gas chromatographymass spectrometry system, evidence was obtained for a number of mono- and sesquiterpene hydrocarbons and some substituted anilines including o -toluidine; for some C 5 and C 6 alcohols and monoterpene alcohols; and for at least one sesquiterpene alcohol. The major components were a series of alkanes, alkenes, and alkyl alcohols of high molecular weight. This investigation was part of a study made to identify possible additional components of the pheromone produced by the boll weevil.