Toxicity of allelochemicals from wild insect-resistant tomatoLycopersicon hirsutum f.glabratum toCampoletis sonorensis,a parasitoid ofHeliothis zea

Greenhouse-grown plants of five tomato lines varying in their level of 2-tridecanone-mediated resistance toManduca sexta (L.) andLeptinotarsa decemlineata (Say) were found to adversely affect larvae ofCampoletis sonorensis (Cameron), a larval endoparasitoid ofHeliothis zea (Boddie), in a manner directly related to their level of resistance. The parasitoid larvae, which emerge as fifth instars from their host and construct a cocoon on the foliage of their hosts' host plant, suffered extensive mortality during cocoon spinning on highly resistant foliage. Mortality was greatest (82%) on the highly resistant plants ofLycopersicon hirsutum f.glabratum (accession PI 134417) and an F₁ backcross [(L. esculentum × PI 134417) × PI 134417] selection. Mortality was intermediate (40 and 28%, respectively) on backcross selections with moderate and low levels of resistance and least (8%) on susceptibleL. esculentum. Removal of the glandular trichomes, which contain 2-tridecanone in their tips, from the foliage eliminated differences in parasitoid mortality among plant lines.Bioassays of 2-tridecanone indicated that it is acutely toxic to fifth instarC. sonorensis larvae at the quantities associated with highly resistant foliage and produces symptoms identical to those observed on resistant foliage. 2-Undecanone, a second methyl ketone present in the glandular trichomes of resistant foliage, was also toxic toC. sonorensis larvae, but significantly less so than 2-tridecanone. The results support the hypothesis that 2-tridecanone is responsible for the observed mortality ofC. sonorensis larvae during cocoon construction on resistant foliage.     

Inhibition ofCampoletis sonorensis parasitism ofHeliothis zea and of parasitoid development by 2-tridecanone-mediated insect resistance of wild tomato

Field populations ofHeliothis spp. were sampled for levels of naturally occurring larval parasitism on six tomato lines varying in levels of 2-tridecanone-mediated resistance toManduca sexta (L.) andLeptinotarsa decemlineata (Say). Second and third instars were parasitized byCampoletis sonorensis (Cameron) (Hymenoptera: Ichneumonidae) andCotesia (=Apantales)marginiventris (Cresson) (Hymenoptera: Braconidae) in 1984 through 1986 and byMicropletis croceipes (Cresson) (Hymenoptera: Braconidae) in 1986. Differences in parasitism by individual and multiple species among host plants were not demonstrated. However, levels of parasitism were low and variable among replicates. Total larval parasitism averaged across all plant lines was less than 6% in 1984 and 1986 and approximately 11% in 1985. In laboratory cage studies,C. sonorensis parasitized fewerH. zea larvae on tomato foliage with high levels of 2-tridecanone than on foliage with low levels. RearingH. zea on diet containing 2-tridecanone and 2-undecanone did not alter incidence of parasitism byC, sonorensis; nor did rearing parasitizedH. zea larvae on chemically treated host diets precondition the parasitoid to higher or lower mortality when transferred to foliage as a substrate for cocoon spinning, regardless of the foliage genotype. However, parasitoid survival during cocoon spinning on foliage varied significantly among plant lines in a manner corresponding to the level of 2-tridecanone-mediated resistance of the foliage. Parasitoid mortality was greatest on highly resistant foliage and lowest on susceptible foliage.     

Responses from sensilla on antennae of maleHeliothis zea to its major pheromone component and two analogs

For some species, chemical analogs have been identified that can substitute for the major pheromone component and reduce pheromone-trap captures in atmospheric permeation experiments. The ability to substitute these analogs for the major pheromone component in field tests raises the question: Do the same set of olfactory receptor neurons on the insects' antennae respond to both the major component and the effective structural analogs? To investigate this question, extracellular responses were recorded from single sensilla on the antennae of maleHeliothis zea (Boddie) (Lepidoptera: Noctuidae) to stimulation with increasing doses of (Z)-11-hexadecenal, the major pheromone component, (Z)-9-tetradecen-1-ol formate, and (Z)-1,12-heptadecadiene. Both (Z)-9-tetradecen-1-ol formate and (Z)-1,12-heptadecadiene can substitute for (Z)-11-hexadecenal in trap disruption experiments and affect the sexual behavior of males, although neither has been identified in the volatiles released by calling females. All three compounds elicited responses from the same class of pheromone-sensitive receptor neurons over a range of stimulus concentrations. At equivalent stimulus concentrations, however, (Z)-11-hexadecenal elicited about a 10-fold greater response than (Z)-1,12-heptadecadiene. (Z)-9-Tetradecen-1-ol formate elicited a response slightly higher than, but not significantly different from, the response to (Z)-1,12-heptadecadiene.     

Effect of day length and light intensity on 2-tridecanone levels and resistance inLycopersicon hirsutum f.glabratum toManduca sexta

First instarManduca sexta (L.) larvae confined on foliage fromLycopersicon hirsutum f.glabratum (accession PI 134417) plants grown under a long-day regime exhibited greater mortality than larvae on foliage from plants grown under a short-day regime. 2-Tridecanone, a toxin important in the insect resistance of PI 134417, was significantly more abundant in the foliage of plants grown under the long-than the short-day regimes. Light intensity influenced neither 2-tridecanone levels nor the expression of resistance. The density of glandular trichomes, which secrete 2-tridecanone, was influenced by an interaction between day length and light intensity.Lepidoptera: Sphingidae.Paper no. 6503 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, North Carolina 27650.     

Plant defenses: Chlorogenic acid and polyphenol oxidase enhance toxicity ofBacillus thuringiensis subsp.kurstaki toHeliothis zea

Two chemicals implicated in resistance of the tomato plant, chlorogenic acid and polyphenol oxidase, are known to form orthoquinones in damaged plant tissue. Orthoquinones have been reported to alkylate –NH₂ and –SH groups of proteins and amino acids, altering solubility, digestibility, and, for some pathogenic viruses, infectivity. Here we explore effects of quinone alkylation on toxicity of an important microbial insecticide,Bacillus thuringiensis subsp.kurstaki (BTk), to larvalHeliothis zea. BTk incubated with these phytochemicals and fed to larvae was more toxic than untreated BTk. Similar but less dramatic results arose when BTk was incubated with polyphenol oxidase alone. Digestibility experiments suggest that alkylation enhanced the solubilization and/or proteolysis of crystal protein in vivo. Implications of our results for compatibility of BTk with host-plant resistance and biological control are discussed.     

Activation of plant foliar oxidases by insect feeding reduces nutritive quality of foliage for noctuid herbivores

The foliage and fruit of the tomato plantLycopersicon esculentum contains polyphenol oxidases (PPO) and peroxidases (POD) that are compartmentally separated from orthodihydroxyphenolic substrates in situ. However, when leaf tissue is damaged by insect feeding, the enzyme and phenolic substrates come in contact, resulting in the rapid oxidation of phenolics to orthoquinones. When the tomato fruitwormHeliothis zea or the beet army-wormSpodoptera exigua feed on tomato foliage, a substantial amount of the ingested chlorogenic acid is oxidized to chlorogenoquinone by PPO in the insect gut. Additionally, the digestive enzymes of the fruitworm have the potential to further activate foliar oxidase activity in the gut. Chlorogenoquinone is a highly reactive electrophilic molecule that readily binds cova-lently to nucleophilic groups of amino acids and proteins. In particular, the —SH and —NH₂ groups of amino acids are susceptible to binding or alkylation. In experiments with tomato foliage, the relative growth rate of the fruitworm was negatively correlated with PPO activity. As the tomato plant matures, foliar PPO activity may increase nearly 10-fold while the growth rate of the fruitworm is severely depressed. In tomato fruit, the levels of PPO are highest in small immature fruit but are essentially negligible in mature fruit. The growth rate of larvae on fruit was also negatively correlated with PPO activity, with the fastest larval growth rate occurring when larvae fed on mature fruit. The reduction in larval growth is proposed to result from the alkylation of amino acids/protein byo-quinones, and the subsequent reduction in the nutritive quality of foliage. This alkylation reduces the digestibility of dietary protein and the bioavailability of amino acids. We believe that this mechanism of digestibility reduction may be extrapolatable to other plant-insect systems because of the ubiquitous cooccurrence of PPO and phenolic substrates among vascular plant species.     

Mortality and inhibition ofHelicoverpa zea Egg parasitism rates byTrichogramma in relation to trichome/methyl ketone-mediated insect resistance ofLycopersicon hirsutum f. glabratum,accession PI 134417

The glandular trichome/methyl ketone-mediated insect resistance of the wild tomato,Lycopersicon hirsutum f. glabratum C.H. Mull, accession PI 134417, toManduca sexta (L.) andLeptinotarsa decemlineata (Say) was shown to affect adverselyTrichogramma pretiosum Riley. AdultT. pretiosum were killed by direct contact with PI 134417 foliage and by exposure to its volatiles. This effect was greatly reduced or eliminated by removing the exudate of the glandular trichomes from the foliage. 2-Tridecanone, a principal consituent of the foliar glandular trichomes of PI 134417, was toxic to adultT. pretiosum at concentrations similar to those associated with PI 134417 foliage. Incubation of parasitizedHelicoverpa (=Heliothis) zea (Boddie) eggs on PI 134417 foliage or 2-tridecanone-treated filter paper significantly reduced the proportion of eggs producing adult parasitoids. Similarly, incubation of parasitizedH. zea eggs on filter paper treated with 2-undecanone, another constituent of the glandular trichomes of PI 134417, caused an increase in the percentage of host eggs containing dead parasitoid pupae.     

Growth inhibitors in tomato (Lycopersicon) to tomato fruitworm (Heliothis zea)

Several compounds that retard the larval growth of the tomato fruitworm,Heliothis zea (Boddie) have been isolated and identified from tomato leaves,Lycopersicon esculentum Mill. The major allelochemics are -tomatine (I), chlorogenic acid (II), rutin (III), and a new caffeyl derivative of an aldaric acid (IV). The isolation, analyses, and toxicity of these compounds toH. zea are presented.Reference to a company and/or product named by the department is only for purposes of information and does not imply approval or recommendation of the product to the exclusion of others which may also be suitable     

Aphid deterrence by glucose esters in glandular trichome exudate of the wild tomato,Lycopersicon pennellii

Settling of the potato aphid,Macrosiphum euphorbiae, on feeding membranes was deterred by methanolic leaf rinses ofLycopersicon pennellii, or of its F₁ with tomato,L. esculentum. The active compounds in theL. pennellii rinsates were identified as 2,3,4-tri-O-acylglucoses bearing short to medium chain length fatty acids. These compounds are localized in the glandular exudate of the type IV trichomes and may accumulate to levels in excess of 400 g/cm². In choice assays, purified glucose esters fromL. pennellii reduced aphid settling at concentrations as low as 25 g/cm²; at concentrations of 150 g/cm² or more, all aphids avoided treated areas. Glucose esters were also active in deterring aphid settling in no-choice assays. At 100 g/ cm², these esters resulted in increased levels of mortality after 48 hr.     

Alkyl ether and enol ether analogs of (Z)-5-decenyl acetate,a pheromone component of the turnip moth,Agrotis segetum: probing a proposed bioactive conformation for chain-elongated analogs

In order to test a previous conclusion that chain-elongated analogs of (Z)-5-decenyl acetate(1), a pheromone component of the turnip moth,Agrotis segetum, adopt a loop conformation of the terminal alkyl chain in the bioactive conformation, a series of alkyl ether and enol ether analogs of1 and (Z)-5-dodecenyl acetate(2) have been synthesized and tested using singlecell electrophysiology. In these analogs a methylene group in positions 7 and 9 of1 and in positions 7 and 11 in2 have been replaced by an oxygen atom in order to energetically facilitate the formation of a loop conformation in the chain-elongated analogs. The electrophysiological results in combination with molecular mechanics (MM2 and MM3) calculated conformational energies show that the activity decreases of the chain-elongated ether analogs are significantly smaller than that for2 and that these activity decreases parallel the conformational energies for a loop formation of the terminal chains in the analogs. The results support our previous conclusion that the terminal chain of chain-elongated analogs of1 adopts a loop conformation in their bioactive conformations.     

Alleviation of α-tomatine-induced toxicity to the parasitoid,Hyposoter exiguae,by phytosterols in the diet of the host,Heliothis zea

The solitary, endoparasitic ichneumonid,Hyposoter exiguae (Viereck) is a parasitoid of the tomato fruitworm,Heliothis zea (Boddie). However, the parasitoid is deleteriously affected by the tomato glycoalkaloid, -tomatine, ingested from hosts (H. zea) fed on artificial diets or semipurified extracts of tomato plants that contained -tomatine. -Tomatine causes prolonged larval development; disruption or prevention of pupal eclosion; deformation of antennal, abdominal, and genital structures; and reduction in adult weight and longevity of the parasitoid. These toxic effects are exacerbated when the dietary dose of -tomatine is increased from 12 mol to 20 mol/g dry wt of diet. However, the toxicity of -tomatine is attenuated in parasitoids reared from hosts fed on artificial diets that contain equimolar or supramolar amounts of 3-OH-sterols admixed with -tomatine. Further, the toxicity of extracts from the foliage of different cultivars of tomatoes toH. exiguae is contingent upon the composite levels of -tomatine and total phytosterol (free and esterified). Cultivars with a low total sterol-tomatine ratio are more toxic toH. exiguae. The possible mode of action of -tomatine toxicity toH. exiguae by disruption of sterol metabolism is discussed.     

Response of the ichneumonid parasiteNemeritis canescens to Kairomones from the flour moth,Ephestia kuehniella

2-Acylcyclohexane-1,3-diones, a novel class of compounds in the larval mandibular glands ofEphestia(=Anagasta) kuehniella Zeller, act as kairomones. Their relative activities in eliciting oviposition responses from the larval parasiteNemeritis(=Venturia) canescens (Grav.) are reported.     

Effects of cuticular duvane diterpenes from green tobacco leaves on tobacco budworm (Lepidoptera: Noctuidae) oviposition

Five cuticular chemical components isolated from the green leaves of tobacco introductions (TIs) and a commercial tobacco cultivar were tested for their effects on tobacco budworm,Heliothis virescens (F), oviposition in cage bioassays, and field experiments. These chemicals were sprayed onto budworm-resistant TI 1112 tobacco which produces low levels of most cuticular components. Individual duvane diterpenes (- and -4,8,13-duvatrien-1-ols and - and -4,8,13-duvatriene-1,3-diols) increased tobacco budworm egg laying on sprayed TI 1112 plants.cis-Abienol, docosanol, and docosanyl myristate were inactive.Mention of a company or proprietary product does not imply endorsement or recommendation by the U.S. Department of Agriculture. Paper No. 9702 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, North Carolina 27695-7601.     

CO2 capture from syngas via cyclic carbonation/calcination for a naturally occurring limestone: Modelling and bench-scale testing

The intrinsic rate constants of the CaO-CO₂ reaction, in the presence of syngas, were studied using a grain model for a naturally occurring calcium oxide-based sorbent using a thermogravimetric analyzer. Over temperatures ranging from 580 to 700 °C, it was observed that the presence of CO and H₂ (with steam) during carbonation caused a significant increase in the initial rate of carbonation, which has been attributed to the CaO surface sites catalyzing the water-gas shift reaction, increasing the local CO₂ concentration. The water-gas shift reaction was assumed to be responsible for the increase in activation energy from 29.7 to 60.3 kJ/mol for limestone based on the formation of intermediate complexes. Changes in microporosity due to particle sintering during calcination have been credited with the rapid initial decrease in cyclic CaO maximum conversion for limestone particles, whereas the presence of steam during carbonation has been shown to improve the long-term maximum conversion in comparison to previous studies without steam present.     

(7R,8S)-cis-7,8-epoxy-2-methyloctadec-17-ene: a novel trace component from the sex pheromone gland of gypsy moth, Lymantria dispar

Considering the vast Eurasian distribution of gypsy moth, Lymantria dispar (Lepidoptera: Lymantriidae), the many subspecies, and their presence in different lymantriid communities, we tested the hypothesis that L. dispar populations in eastern Asia employ one or more pheromone components in addition to the previously known single component pheromone (7R,8S)-cis-7,8-epoxy-2-methyloctadecane [= (+)-disparlure]. Coupled gas chromatographic–electroantennographic detection (GC–EAD) analyses of pheromone gland extracts of female L. dispar sensu lato (including both AGM and NAGM) on four GC columns (DB-5, DB-23, DB-210, and SP-1000) revealed a new trace component that eluted just before (DB-5; DB-210) or after (DB-23, SP-1000) disparlure, and elicited strong antennal responses. Isolation of this compound by high-performance liquid chromatography and hydrogenation produced disparlure, suggesting that the new component had the molecular skeleton of disparlure, with one or more double bonds. Of all possible monounsaturated cis-7,8-epoxy-2-methyloctadecenes, only cis-7,8-epoxy-2-methyloctadec-17-ene co-chro- matographed with the insect-produced compound on all GC columns and elicited comparable antennal responses. In field experiments in Honshu (Japan) with enantioselectively synthesized compounds, (7R,8S)-cis-7,8-epoxy-2- methyloctadec-17-ene (7R8S-epo-2me-17-ene-18Hy) was weakly attractive to male L. dispar, but was less effective as a trap bait than (+)-disparlure, and failed to enhance attractiveness of (+)-disparlure when tested in blends. The antipode, (7S,8R)-cis-7,8-epoxy-2-methyloctadec-17-ene, was not attractive, and when added to (+)-disparlure and/or 7R8S-epo-2me-17-ene-18Hy reduced attractiveness. Thus, the biological role of 7R8S-epo-2me-17-ene-18Hy remains unclear. It may enhance pheromone attractiveness or specificity in other L. dispar populations within their vast Eurasian distribution.     

Improvement of the growth of Arthrospira (Spirulina) platensis from Toliara (Madagascar): Effect of agitation, salinity and CO2 addition

Arthrospira (Spirulina) platensis Toliara isolated from alkaline and salt lakes in the south-western area of Madagascar is a potential source of proteins that could efficiently fight against food deficiency in developing countries like Madagascar. Up to now, productivity in this country has been low, so a better understanding of the growth conditions of this species is needed to improve its production. Growth experiments were undertaken in bubble columns at laboratory scale. The influence of agitation of the culture, medium salinity (ranging from 13 to 35 g L⁻¹) and CO₂ addition (ranging from 0 to 2%, v/v) on growth and protein content was examined. Because Arthrospira cells are fragile, a bubble column without additional mixing gave the best growth. Arthrospira (Spirulina) platensis showed higher specific growth rate (μ_max) and protein content for lower salinity. Addition of 1% of CO₂ improved the productivity by near 60%. The feasability of semi-continuous culture was demonstrated and optimal culture conditions led to a mean productivity of 0.22 ± 0.03 g L⁻¹ d⁻¹, a mean specific growth rate of 0.015 ± 0.002 h⁻¹ and a protein content of 53 ± 2% of total dry weight.     

Variation of LiNiO<Subscript>2</Subscript> cathode properties with substitution of Ga,In and Tl by the combustion method

LiNi_1-y M_yO₂ (M = Ga, In and Tl, y = 0.010, 0.025 and 0.050) with small y were synthesized by the combustion method by calcining in an O₂ stream at 750 °C for 36 h. XRD analyses, SEM observation and measurement of the variation of discharge capacity with the number of cycles were carried out. All the samples had the Rm structure and LiNi_1-y In _y O₂ contained LiInO₂ phase as an impurity. Among LiNi_1-y Ga _y O₂ the sample with y = 0.025 had a relatively large first discharge capacity (172.2 mAh g⁻¹) and relatively good cycling performance (discharge capacity 140.3 mAh g⁻¹ at n = 20). For LiNi_0.975M_0.025O₂ (M = Ga, In and Tl), the first discharge capacity decreased in the order of the substituted element Ga, In and Tl. The variations of cation mixing and hexagonal ordering with the substituted element (decrease in I₀₀₃/I₁₀₄ and increase in R-factor from M = Ga through M = Tl) are considered to lead to the behavior of the first discharge capacity with the substituted element. LiNi_0.975Tl_0.025O₂ had the smallest degradation rate of the discharge capacity.     

Reduction of NO2 stored in a commercial lean NO x trap at low temperatures

Isothermal storage of NO₂ and subsequent reduction with different reducing agents (H₂, CO or H₂ + CO) in a lean NO _x trap catalyst was tested by Temperature Programmed Desorption (TPD) and Temperature Programmed Reduction (TPR) experiments at temperatures representative of automotive “cold-start” conditions (<200 °C) using a commercial NO _x trap catalyst. Results from the TPR experiments revealed that no reduction of stored NO₂ to N₂ was observed at 100–180 °C, and at 200 °C 10% reduction only of NO₂ to N₂ was measured. A special affinity of H₂ to form NH₃ was observed during the reduction of stored NO₂. The formation of NH₃ increases with increasing amount of stored NO₂ and decreases with increasing storage temperature. Direct relation exists between the amount of adsorbed and/or stored NO₂ and the formation of H₂O and NH₃.     

Consumption and Metabolism of 1,2-Dimethoxy-4-(3-Fluoro-2-Propenyl)Benzene, a Fluorine Analog of Methyl Eugenol, in the Oriental Fruit Fly Bactrocera dorsalis (Hendel)

Methyl eugenol (ME) is a natural phenylpropanoid highly attractive to oriental fruit fly Bactrocera dorsalis (Hendel) males. The flies eagerly feed on ME and produce hydroxylated metabolites with both pheromonal and allomonal functions. Side-chain metabolic activation of ME has long been recognized as a primary reason for hepatocarcinogenicity of this compound on rodents. In an attempt to develop a safer alternative to ME for fruit fly management, we developed a fluorine analog 1,2-dimethoxy-4-(3-fluoro-2-propenyl)benzene (I), which, in earlier field tests, was as active to the oriental fruit fly as ME. Now we report that B. dorsalis males are not only attracted to, but also eagerly consume (up to ∼1 mg/insect) compound I, thus recognizing this fluorinated benzene as a close kin of the natural ME. The flies metabolized the fluorine analog I in a similar fashion producing mostly two hydroxylated products, 2-(3-fluoro-2-propenyl)-4,5-dimethoxyphenol (II) and (E)-coniferyl alcohol (III), which they stored in rectal glands. However, the introduction of the fluorine atom at the terminal carbon atom of the double bond favors the ring hydroxylation over a side-chain metabolic oxidation pathway, by which coniferyl alcohol is produced. It also appears that fluorination overall impedes the metabolism: at high feed rate (10 μl per 10 males), the flies consumed in total more fluorine analog I than ME but were unable to metabolize it as efficiently as ME.     

Investigation of ternary system Pb(Sn,Ti)O3-Pb(Mg1/3Nb2/3)O3 with morphotropic phase boundary compositions

(1 − x)Pb(Sn_1−yTi_y)O₃-xPb(Mg_1/3Nb_2/3)O₃ (x = 0.1-0.4, y = 0.45-0.65) ternary system was prepared using two-step columbite precursor method. Phase structure of the synthesized ceramics was studied by using X-ray powder diffraction and the morphotropic phase boundary (MPB) curve of the ternary system was confirmed. The isothermal map of Curie temperature (T_C) in the phase diagram was obtained based on the dielectric-temperature measurements. The coercive field E_C and internal bias field E_i were found to increase with increasing PT content, while decrease with increasing PMN content. The optimum properties were achieved in the MPB composition 0.8Pb(Sn_0.45Ti_0.55)O₃-0.2Pb(Mg_1/3Nb_2/3)O₃, with dielectric permittivity ?_r, piezoelectric coefficient d₃₃, planar electromechanical coupling k_p, mechanical quality factor Q_m and T_C of being on the order of 3040, 530pC/N, 55.5%, 320 and 190 °C, respectively, exhibiting potential usage for high power application.