Chemical Stimuli from Apple Influence the Behavior of Neonate Caterpillars of the Generalist Herbivore, Epiphyas postvittana

When introduced into a wind tunnel with low windspeeds (0.2–0.3 m/sec), neonate E. postvittana larvae were more likely to walk in a downwind rather than upwind direction. This tendency to walk downwind did not change when odors from apple leaves or fruit were introduced into the wind tunnel. In a second assay that measured travel times of larvae as they walked from the center to the edge of filter paper disks, larvae moved more slowly on disks treated with extracts of apple leaves or extracts of apple fruit, but did not slow their movement on disks treated with extracts of a nonhost, Coprosma repens. Analysis of videorecords revealed that larvae on disks treated with a dichloromethane extract of apple leaves took more circuitous routes, walked more slowly, and stopped more frequently than larvae walking on solvent-treated disks. When the dosage of this dichloromethane apple leaf extract was increased or when larvae were held without food prior to testing, differences between travel times on solvent- and extract-treated disks did not increase significantly. The dichloromethane apple leaf extract, when tested in the wind tunnel with low windspeeds, also caused larvae to delay spinning down on a silken thread after reaching the edge of the disk, but had no effect on spin-down times when tested in still-air conditions. Testing of rotary evaporated apple leaf extracts and fractionation of these extracts indicated that a number of both volatile and relatively involatile chemicals contribute to the behavioral responses of E. postvittana larvae.     

Absorption and release of pheromone ofEpiphyas postvittana (Lepidoptera: Tortricidae) by apple leaves

The absorption and release of the pheromone ofEpiphyas postvititana (Lepidoptera: Tortricidae),E 11–14: OAc andE,E 9, 11–14: OAc (95:5) by apple leaves was studied using electroantennograms (EAG) and sticky traps baited with pheromone-treated leaves. Leaves exposed to an airstream containing pheromone reached a constant level of pheromone release within 3 min. Release occurred over a period greater than 24 hr, following removal of leaves from the pheromone-saturated environment. Pheromone-treated leaves were effective as lures in sticky traps for at least three nights, although the average catch per night decrease logarithmically with time. In the field, pheromone was detected by EAG on leaves harvested from up to 25 cm away from a central point source of pheromone. The shape of a surface representing equal pheromone re-release from leaves around a central point source was defined by interpolation from a three-dimensional transect. Leaves harvested from 5 cm under the dispensers showed the highest pheromone release rate. Leaves downwind of the dispensers also had higher release of pheromone. In a treated orchard, significantly higher EAG measurements were recorded in the rows of trees that contained dispensers, compared to grass interrows or untreated trees. The implications of foliar pheromone adsorption and release on atmospheric concentrations and insect behavior require further investigation.     

Apple foliage enhances mating disruption of light-brown apple moth

Uptake and release of pheromone and behavioral inhibitor ofEpiphyas postvittanna by apple leaves was tested using field electroantennograms (EAG), trap catches to synthetic lures and virgin females, and chemical analysis. Trap catches in single apple trees (N=3) were monitored for six cycles of six days' duration, using delta traps baited with synthetic pheromone. Polyethylene dispensers (0, 1, 10 per tree) releasing pheromone and inhibitor were present for only the first three days of each cycle. Application of 10 dispensers per tree resulted in complete disruption of trapping, which continued for one day after dispensers were removed. Over the three nights following the removal of the dispensers (days 4–6), trap catch was 0, 10, and 15% of the control catch. In contrast, the presence of only one dispenser per tree led to 0–20% of control catches, but on the three nights following dispenser removal catches were 35, 40, and 80% of the control catch. Field EAGs indicated significantly higher relative pheromone concentrations in the trees with 10 dispensers present, compared to trees with single dispensers, but removal of dispensers produced no detectable treatment effect compared to the control trees one day after dispenser removal. In a second experiment, releases of marked male moths into apple orchard plots following the removal of polyethylene dispensers (1 hr earlier that day) resulted in significantly lower catches in traps baited with virgin females in blocks that had been treated, compared to controls. Recovery of pheromone by solvent washing of leaves loaded with 50 µg of the main component of the sex pheromone (1.26 µg/cm²) was low (2.5%). Leaves held in a pheromone-saturated atmosphere were loaded with 0.045±0.007 µg pheromone/cm². Analysis of apple leaves taken from a pheromone-treated tree at different distances from the pheromone dispenser showed a decay of the pheromone load per square centimeter with increasing distance from the dispenser, as previously indicated by EAG.     

Spatial discrimination between sources of pheromone and an inhibitor by the light-brown apple mothEpiphyas postvittana (Walker) (Lepidoptera: Tortricidae)

Inhibition of the behavioral responses of maleEpiphyas postvittana moths by theZ isorner of the major component of the sex pheromone,E11-14: OAc, was studied in a wind tunnel. Inhibition was detectable at a Z isomer concentration of 10% that of the major component and was greatest when it was added to the same source as the pheromone. Inhibition declined rapidly as the inhibitor was moved across-wind away from the pheromone source but was largely maintained when the sources were separated upwind or downwind. The results showed that the insects possess a high degree of temporal resolution for odor plumes of different composition.     

Differences in Effects of Pyrrolizidine Alkaloids on Five Generalist Insect Herbivore Species

The evolution of the diversity in plant secondary compounds is often thought to be driven by insect herbivores, although there is little empirical evidence for this assumption. To investigate whether generalist insect herbivores could play a role in the evolution of the diversity of related compounds, we examined if (1) related compounds differ in their effects on generalists, (2) there is a synergistic effect among compounds, and (3) effects of related compounds differed among insect species. The effects of pyrrolizidine alkaloids (PAs) were tested on five generalist insect herbivore species of several genera using artificial diets or neutral substrates to which PAs were added. We found evidence that structurally related PAs differed in their effects to the thrips Frankliniella occidentalis, the aphid Myzus persicae, and the locust Locusta migratoria. The individual PAs had no effect on Spodoptera exigua and Mamestra brassicae caterpillars. For S. exigua, we found indications for synergistic deterrent effects of PAs in PA mixtures. The relative effects of PAs differed between insect species. The PA senkirkine had the strongest effect on the thrips, but had no effect at all on the aphids. Our results show that generalist herbivores could potentially play a role in the evolution and maintenance of the diversity of PAs.     

Effect of design of a sex-pheromone-baited delta trap on behavior and catch of maleEpiphyas postvittana (Walker)

Through field trials and wind-tunnel studies, we have demonstrated that certain structural features of a sex-pheromone-baited delta trap affect catch of light-brown apple moth,Epiphyas postvittana, males, by influencing behaviors used to enter and exit the trap. Field catch of males was dependent upon length (and width) of the trap, with increases in length yielding linear increases in catch. In the wind tunnel, similar numbers of males entered the two traps, but significantly fewer males exited the longer trap within 1 min after entering it. Although males landed on the sticky surface at similar distances from the downwind entrances of the traps, they were stuck farther upwind on the longer trap. Thus, it is probable that the increase in field catch with increase in trap length relates to the increase in distance (and hence time) that males walk on the sticky surface, towards the pheromone source, before attempting to exit. The bottom barriers (as well as additional barriers at the top and sides) at the entrances of the trap also significantly influenced trap catch. The barriers apparently influence trap catch in two ways. Firstly, they hinder the exit of males from the trap, thus diverting males back into the trap and increasing their chance of being caught. Secondly, they influence where the male lands on the sticky surface; with higher barriers, males land farther upwind (i.e., nearer the source), and thus farther from an exit. Finally, as the source was suspended higher above a horizontal surface, greater numbers of males landed on the source. This result shows that the position where a maleE. postvittana lands is influenced by the relationship of the source to the surface and suggests that trap catch of males may similarly be influenced (i.e., by inducing males to land farther from the exits).     

Biosynthesis of sex pheromone components and glycerolipid precursors from sodium [1-14C]acetate in redbanded leafroller moth

Sodium [1-¹⁴C]acetate in water-dimethyl sulfoxide (11) was applied topically to sex pheromone glands ofArgyrolaenia velutinana. Radiolabel was incorporated into the pheromone components (Z)-11-tetradecenyl acetate and (E)-11-tetradecenyl acetate, and also into triacylglycerols, diacylglycerols, ethanolamine phosphatides, and choline phosphatides. In the triacylglycerols, radiolabel appeared in (Z)-11-tetradecenoate, (E)-11-tetradecenoate, tetradecanoate, hexadecanoate, and octadecanoate. In the choline phosphatides, the same acyl moieties incorporated radiolabel but at lower levels. In the diacylglycerols and ethanolamine phosphatides, only the radiolabel in hexadecanoate and octadecanoate was above the limit of detection. At different times following application of sodium [1-¹⁴C]acetate, the relative proportions of labeled (Z)-11-tetradecenyl acetate and (E)-11-tetradecenyl acetate changed very little, but the relative proportions of labeled fatty acyl moieties in the triacylglycerols and choline phosphatides changed markedly. After 8 min, triacylglycerols had incorporated about equal amounts of radiolabel into (Z)-11-tetradecenoate, (E)-11-tetradecenoate, and tetradecanoate. As the incubation time was increased, triacylglycerols accumulated proportionately more radiolabeled (E)-11-tetradecenoate than (Z)-11-tetradecenoate, and accumulated proportionately less radiolabeled tetradecanoate. In the choline phosphatides, at all times of incubation the amount of radiolabel incorporated into (Z)-11-tetradecenoate was small but above the limit of detection, and the amounts of radiolabel in (E)-11-tetradecenoate and tetradecanoate were smaller and often below the limit of detection. In both the triacylglycerols and the choline phosphatides, the relative proportion of radiolabeled hexadecanoate decreased with time, and that of octadecanoate increased.     

Alarm Response of Arius felis to Chemical Stimuli from Injured Conspecifics

The hardhead catfish (Arius felis) showed increased activity when subjected to water containing chemical cues of injured conspecifics. This response was similar to the visually stimulated response to a model of a predatory fish. Arius felis also responded to chemical cues of injured sailfin mollies (Poecilia latipinna) with increased activity, but this was less than in response to conspecific chemical cues. A histological examination of Arius felis epidermis revealed that the alarm substance cells of marine catfish are similar to those of freshwater catfish. Responses to odors of injured individuals is common among ostariophysans, which are mostly freshwater fishes. This is the first demonstration of an alarm reaction in a marine ostariophysan.     

Behavioral Response of Female Codling Moths, Cydia pomonella, to Apple Volatiles

Apple volatiles stimulated pheromone release, oviposition, and upwind orientation in female codling moths, Cydia pomonella. Green apples increased the percentage of virgin females calling, the duration of female calling, and advanced the onset of egg-laying in gravid females. In a tube olfactometer, both virgin and mated females were more active in the presence of apple volatiles than in clean air. They responded by walking while wing-fanning; mated females showed a stronger attraction response than unmated females.     

Interactions Among Insect Herbivore Guilds: Influence of Thrips Bud Injury on Foliar Chemistry and Suitability to Gypsy Moths

This study investigated the consequences of early season bud herbivory on host-plant phytochemistry and subsequent effects on a later mid-season leaf-feeding herbivore, to test the hypothesis that temporally segregated interguild interactions could affect herbivore success through plant-mediated responses. Our system consisted of American bass wood, Tilia americana, a bud-feeding thrips species, Thrips calcaratus, and the folivorous gypsy moth, Lymantria dispar. The impact of thrips bud-feeding on American basswood foliar chemistry and subsequent effects on gypsy moth larval preference and performance were measured. Foliar total nonstructural carbohydrates increased and phenolic levels decreased in response to bud injury, which affected larval feeding preference. In a two-choice test, gypsy moth larvae preferred leaf discs with high carbohydrate and low phenolic levels. The effects on larval performance depended on the extent of prior bud injury and were correlated with carbohydrate concentrations. In an early season assay, larval performance was lowest on moderately bud-damaged tissue, which also had the lowest total nonstructural carbohydrates. In a mid-season assay, larval performance and carbohydrate concentrations were highest in severely bud-damaged foliage. Foliar phenolics were highest in severely bud-damaged tissue in the early season assay, and in moderately damaged tissue in the mid-season assay. Gypsy moth performance was not correlated with foliar phenolic levels. Secondary (reflushed) foliage had higher carbohydrate levels than did primary (original) foliage, which correlated with increased larval performance. This study illustrates that bud-feeding herbivores can alter the phytochemistry and subsequent suitability of host-plant foliage for later folivores. The implications of these results to interactions between feeding guilds, community structure, and forest health are discussed.     

Influence of Chemical Extraction on Rheological Behavior,Viscoelastic Properties and Functional Characteristics of Natural Heteropolysaccharide/Protein Polymer from Durio zibethinus Seed

In recent years, the demand for a natural plant-based polymer with potential functions from plant sources has increased considerably. The main objective of the current study was to study the effect of chemical extraction conditions on the rheological and functional properties of the heteropolysaccharide/protein biopolymer from durian (Durio zibethinus) seed. The efficiency of different extraction conditions was determined by assessing the extraction yield, protein content, solubility, rheological properties and viscoelastic behavior of the natural polymer from durian seed. The present study revealed that the soaking process had a more significant (p < 0.05) effect than the decolorizing process on the rheological and functional properties of the natural polymer. The considerable changes in the rheological and functional properties of the natural polymer could be due to the significant (p < 0.05) effect of the chemical extraction variables on the protein fraction present in the molecular structure of the natural polymer from durian seed. The natural polymer from durian seed had a more elastic (or gel like) behavior compared to the viscous (liquid like) behavior at low frequency. The present study revealed that the natural heteropolysaccharide/protein polymer from durian seed had a relatively low solubility ranging from 9.1% to 36.0%. This might be due to the presence of impurities, insoluble matter and large particles present in the chemical structure of the natural polymer from durian seed.     

改性褐煤活性焦对模拟烟气中汞的脱除研究

为降低烟气脱汞成本,提高活性焦脱汞性能,以内蒙古锡林浩特褐煤为原料制备活性焦并进行化学改性,分析载硫、Na2S溶液和Zn Cl2溶液浸渍等改性方法对活性焦结构及性能的影响,研究改性方法、吸附温度、负载量和汞渗透量对活性焦脱汞性能的影响。结果表明,活性焦改性后,比表面积和孔容积有所降低,载Na2S、硫、Zn Cl2活性焦对汞的吸附量比原始活性焦分别提高了60%、113%和140%;吸附温度升高,化学反应变快,活性焦的初始脱汞效率由75.8%提高至95%以上,但穿透时间并不呈比例增加;当Zn Cl2负载量由5%提高至15%后,50%穿透率对应时间由75 min延长至120 min,活性焦对汞的吸附值由10.1μg/g增至17.5μg/g。随着汞渗透量的增加,活性焦脱汞效率有所提高,50%穿透率的对应时间由110 min缩短至95 min,最终总吸附值仅由14.4μg/g增至16.2μg/g。     

Influence of pheromone trap color and design on capture of male velvetbean caterpillar and fall armyworm moths (Lepidoptera: Noctuidae)

Three pheromone traps were evaluated in paired field trials for effectiveness in capturing wild male velvetbean caterpillar moths (VBC),Anticarsia gemmatalis Hübner, and fall armyworm moths (FAW),Spodoptera frugiperda (J.E. Smith), using a wind-oriented trapping device. The traps were: (1) the standard multicolored bucket trap consisting of a forest green canopy, yellow funnel, white bucket and open (i.e., single wire) pheromone holder; (2) a forest green monocolored bucket trap; and (3) the Multi-Pher-1 trap consisting of a blue-green canopy, white funnel, white bucket, and white, multislotted pheromone holder. The Multi-Pher-1 trap differs primarily from the other two in that its entrance is smaller in diameter and is partially obstructed by the pheromone holder. Significantly fewer VBC and FAW males were captured in pheromone-baited monocolored (forest green) bucket traps than standard multicolored bucket traps. The Multi-Pher-1 trap also caught significantly fewer VBC moths than the standard multicolored bucket trap, but there was no significant difference in numbers of FAW moths caught in the two traps. The results further demonstrate the importance of considering visual cues, in this case color, in the design of pheromone traps for nocturnal insects.This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or the recommendation for its use by USDA.     

Effects of dodecyl acetate andZ-10-tridecenyl acetate on attraction ofEupoecilia ambiguella males to the main sex pheromone component,Z-9-Dodecenyl acetate

Attraction ofE. ambiguella males toZ-9-dodecenyl acetate (Z9-12Ac), alone and in combination with dodecyl acetate (12Ac) orZ-10-tridecenyl acetate (Z10-13Ac) was tested in both wind-tunnel and field experiments. In the laboratory, response toZ9-12Ac reached a distinct dosage optimum at which attraction was nearly as good as to live females. Addition of 12Ac, a minor component of female glands and effluvia, had no effect at low doses ofZ9-12Ac and only marginally improved attraction at the optimum. However, inclusion of 12Ac with an overdose ofZ9-12 Ac fully restored activity. In the field,Z9-12Ac alone was not very attractive at any dose; catches markedly increased by adding 12Ac and climbed with increasing dose of each compound up to 10 mg. Optimum ratio ofZ9-12Ac to 12Ac was 11 to 15. Another compound,Z10-13Ac, had the same effect as 12Ac in the laboratory and the field but was effective at a lower dose. In the field, inclusion of the synergist permits use of high cap loads to attract more males, perhaps from greater distances.     

Influence of trichome exudates from species ofLycopersicon on oviposition behavior ofHeliothis zea (Boddie)

Cage experiments revealed that accessions of the wild tomato speciesLycopersicon hirsutum were preferred sites for oviposition byHeliothis zea. Hexane extracts from the leaves ofL. hirsutum were also preferred sites of oviposition in choice experiments among extracts from severalLycopersicon species. Extracts ofL. hirsutum were still biologically active several days after application, indicating that the phytochemical(s) involved are relatively stable and of low volatility. Gas Chromatographic analysis of leaf hexane extracts from 12 different accessions of theL. hirsutum complex and three tomato cultivars revealed substantial qualitative and quantitative variation in the chemical composition of these extracts. Comparison of these results with extract oviposition studies implicate a group of structurally related compounds as the active agents. Mass spectroscopy has tentatively identified these compounds as sesquiterpenes with the chemical formula C₁₅H₂₂O₂. These compounds are apparently synthesized and secreted from glandular trichomes on the leaf surface. These phytochemicals did not stimulate ovipositional behavior in females of the cabbage looper,Trichoplusia ni. The existence of genetic variation for the presence and amount of kairomones that serve as cues for insect orientation and oviposition could be utilized in a breeding program to develop tomato cultivars with genetically modified allelochemic profiles that would disrupt the sequential behavioral processes of insect host-plant selection.