Identification of sex pheromone components ofSpodoptera sunia Guenée (Lepidoptera: Noctuidae)

Moths belonging to the speciesSpodoptera sunia have been recognized as a new pest of cotton in Central America. By means of electro-physiologic investigations, solid sample injection gas chromatography, and combined gas chromatography-mass spectrometry, (Z)-9-tetradecenyl acetate, (9Z,12E)-9,12-tetradecadienyl acetate, (Z)-9-tetradecen-1-ol, and (Z)-11-hexadecenyl acetate, in a ratio of 10053120, were identified in the pheromone gland of female insects. These substances should serve as a base for the development of a pheromone-monitoring system for this lepidopteran pest.Pheromones, 60. Pheromones 59: Bestmann, HJ., Attygalle, A.B., Brosche, T., Erler, J., Platz, H., Schwarz, J., Vostrowsky, O., Wu Cai-Hong, Kaissling, K.E. and Chen Te-Ming. 1987. Z.Naturforsch. 42c:631–636.     

Mating and oviposition byCotesia (=Apanteles) marginiventris (Hymenoptera: Braconidae) in presence of synthetic pheromone ofSpodoptera frugiperda (Lepidoptera: Noctuidae)

Two blends of fall armyworm,Spodoptera frugiperda (J.E. Smith), pheromonal components were evaluated in the laboratory for possible close-range effects on mating and oviposition byCotesia marginiventris (Cresson). Neither a two- nor a five-component blend had any significant effect on mating or parasitization ofS. frugiperda larvae by this parasitoid. Dosages of 200, 400, and 800 g were tested.     

Effects of dietary protein and lupine alkaloids on growth and survivorship ofSpodoptera eridania

Toxic chemicals and nutrients are often positively correlated within and among plants. We studied how such correlations affect the suitability of plants as food for herbivores by assessing the growth and survivorship ofSpodoptera eridania (army worm) on artificial diets containing lupine alkaloids and casein. We found that (1) the effects of casein were determined by other dietary components: increased dietary casein led to increased larval growth only when the diet was also high in wheat germ. (2) Dietary alkaloids were effective at very low concentrations, reducing both growth and survivorship. The alkaloids lupanine and sparteine were not synergistic in their effects, and the interaction between alkaloids and casein was significant only in the low-wheat-germ diets. (3) The effects of casein and alkaloids were generally apparent only in the first instar, and the growth of fifth-instar larvae was unaffected by diet. (4) Using these artificial diet experiments, we can make simple predictions about the food quality of plants grown under various nutrient regimes. These predictions are consistant with recent ideas about optimal plant defenses.     

Investigation of oviposition deterrent in larval frass ofSpodoptera littoralis (Boisd.)

Previous experiments demonstrated an oviposition-deterring effect of larval frass in the Egyptian cotton leaf worm,Spodoptera littoralis (Boisd.). In this study, females were shown to perceive the oviposition-deterring substance(s) with their antennae. During dark, airtight, and cold (–10 °C) storage, the deterrent was persistent for at least 395 days. On the other hand, larval frass retained its activity for only two days when applied to cotton leaves. The deterrent activity of frass was independent of larval density. Frass of larvae reared at high densities deterred oviposition as well as frass of larvae feeding separately or in small groups. For significant oviposition deterrence, the minimum amount of frass was in the range of 5–10 mg frass per cotton leaf. An acetone extract of larval frass was highly deterrent, in contrast to extracts prepared with water, ethanol, chloroform, or pentane.     

Heliothis subflexa (Gn.) (Lepidoptera: Noctuidae): Demonstration of oviposition stimulant from groundcherry using novel bioassay

Methanol extracts of homogenized groundcherry,Physalis angulata, leaves increased egg deposition byHeliothis subflexa (Gn.) (HS) on treated tobacco plants (a nonhost) 8.5-fold over untreated controls. In doseresponse tests using whole-leaf washes of groundcherry leaves, the threshold of positive response vs. no response to the chemical stimulant was within one log dose unit when compared to the controls. This response was consistent whether the chemical was evaluated on plants in greenhouse-cage tests or in an olfactometer using pieces of broadcloth as the oviposition substrate. The olfactometer used allows year-round study of the behavioral effects of plant allelochemics on insect oviposition behavior in a controlled environment.This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or the recommendation of its use by USDA.     

Biological amplification for increasing electroantennogram discrimination between two female sex pheromones ofSpodoptera littoralis (Lepidoptera: Noctuidae)

MaleSpodoptera littoralis stimulated by a mixture ofS. littoralis female sex pheromone with a positional isomer and by the pheromone alone, gave greatly amplified electroantennograms (EAGs) when the antennae were connected in series. The technique is described and examples are given of its use in screening extracts for EAG activity. Dose-response curves obtained with this technique are presented and discussed. Through biological amplification, EAG discrimination between the pheromones was increased.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel, No. 238-E, 1980 series.     

Spodoptera exigua Oviposition and Larval Feeding Preferences for Pigweed, Amaranthus hybridus, over Squaring Cotton, Gossypium hirsutum, and a Comparison of Free Amino Acids in Each Host Plant

The beet armyworm, Spodoptera exigua (Hübner), can utilize a number of different host plants for oviposition and larval development, but some host plants are preferred over others. This study, using cage choice tests and olfactometer assays, demonstrates the beet armyworm's preference for pigweed, Amaranthus hybridus L., over cotton, Gossypium hirsutum L. Cage and olfactometer choice assays indicated that olfaction plays an important role in host selection by ovipositing females. First instars exhibited no feeding preference, but the more mobile third instars showed a significant feeding preference for excised pigweed leaves. The higher quantities and more diverse accumulations of free amino acids in pigweed might, in conjunction with other physiochemical and mechanical attractant and deterrent factors in the two-plant species system, play roles in the tendency of the beet armyworm to select pigweed over cotton and in providing a superior array of easily absorbed amino acids as compared to cotton.     

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 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.     

Behavior ofHeliothis virescens (F.) in presence of oviposition deterrents from elderberry

Extracts prepared from elderberry,Sambucus simpsonii Rehd., leaves with either acetone, dichloromethane, distilled water, ethanol, hexane, or methanol deterred oviposition byHeliothis virescens (F.) on treated substrates in the laboratory. Doses of the aqueous extract equivalent to as little as 0.8 mg of leaves/cm2 of oviposition substrate were effective in reducing egg deposition. There was no significant difference in the mean number of landings on extract-treated and untreated surfaces. When either the antennae, proboscis, or the metathoracic legs were removed from female moths, there was no significant effect on oviposition on paper towels treated with elderberry leaf-water extract in laboratory bioassays, but in field cages, moths without these appendages deposited significantly fewer eggs on treated leaves of tobacco plants, a preferred host. There was no evidence that elderberry leaf-water extract affected mating byH. virescens.Lepidoptera: Noctuidae.Mention of a commercial or proprietary product does not constitute an endorsement by the USDA.     

Differences in sex pheromone communication systems of closely related species:Spodoptera latifascia (walker) andS. descoinsi lalannecassou & silvain (Lepidoptera: Noctuidae)

S. latifascia andS. descoinsi are closely related species that occur sympatrically over limited areas in French Guiana. We examined allopatric populations,S. latifascia originating from Barbados andS. descoinsi from French Guiana. Studies on nocturnal activity cycles showed temporal partitioning of female calling behavior, male sexual activity, and mating behavior.S. descoinsi were sexually active in the first half of the scotophase whereasS. latifascia were sexually active in the second half. Seven compounds (Z9–14: Ac,Z9,E12–14: Ac,Z11–16: Ac,E9,E12–14: Ac,Z9–14: Ald,Z9,E11–14: Ac andZ11–14: Ac) were identified in females of bothS. latifascia andS. descoinsi extracts.Z9–14: Ac was a main pheromone component for the two species. The major difference between the pheromones ofS. latifascia andS. descoinsi was the proportion ofZ9,E12–14: Ac in the extracts: 7% forS. latifascia and 42% forS. descoinsi. The proportion ofZ9,E12–14: Ac relative to the sum ofZ9–14: Ac andZ9,E12–14: Ac in individual gland extracts was 4±1% (mean ± standard deviation) forS. latifascia and 44.8±6% forS. descoinsi. Electrophysiological studies showed no major differences between species in the morphology and physiology of the pheromone receptors of males. Receptors were identified forZ9–14: Ac andZ9,E12–14: Ac, but no receptor was found for the other compounds. In the wind tunnel, synthetic blends withZ9–14: Ac andZ9,E12–14: Ac gave the same behavioral responses as conspecific female extracts for the males of the two species. Some cross-attraction was observed with synthetic blends and female extracts. Nethertheless, previous field trapping experiments in French Guiana were species-specific and suggested differences in the attractivity of males. In the laboratory,S. latifascia andS. descoinsi could hybridize in both reciprocal crosses. FemaleS. descoinsi × maleS. latifascia mating rate was significantly lower than for the reciprocal cross, and 26.7% of femaleS. descoinsi could not separate from maleS. latifascia after mating. These copulatory problems may involve genital incompatibilities between males and females. Several barriers against interbreeding betweenS. latifascia andS. descoinsi seem to combine including differences in nocturnal activity cycles, pheromone differences, and genital barriers. The study of sympatric populations will be necessary to define the role of sex pheromones in the reproductive isolation ofS. latifascia andS. descoinsi.     

Analysis and field evaluation of volatile blend emitted by calling virgin females of beet armyworm moth,Spodoptera exigua (Hübner)

The volatile blend emitted by calling virgin beet armyworm females was collected and analyzed by capillary gas chromatography and mass spectrometry. Five compounds were detected and identified in this blend: (Z)-9-tetradecenyl acetate, (Z)-9-tetradecen-l-ol, (Z,E)-9,12-tetradecadienyl acetate (Z,Z)-9,12-tetradecadienyl acetate, and (Z)-l 1-hexadecenyl acetate. They were emitted in a ratio of 47.9 4.040.2 6.5 1.7, respectively. This five-component blend and several other blends with one or more components deleted were formulated on rubber septa to release the components in about the same ratios as the females. Field tests of these formulations in bucket traps indicated that a blend of (Z)-9 tetradecen-1-ol, (Z,E)-9,12-tetradecadienyl acetate, and (Z)-l 1-hexadecenyl acetate was most effective for trapping beet armyworm males and that (Z)-9-tetradecenyl acetate actually decreased trap captures. Blends that did not contain both (Z)-9-tetradecen-l-ol and (Z,E)-9,12-tetradecadienyl acetate were ineffective as trap baits.     

Insect antifeedant activity of clerodane diterpenoids against larvae ofSpodoptera Littoralis (Boisd.) (Lepidoptera)

Antifeedant activities of nine clerodane diterpenoids, isolated in this laboratory from different species ofAjuga plants, have been studied against larvae of Egyptian cotton leafwormSpodoptera littoralis (Boisd.) (Lepidoptera) by application of the leaf disk method. Evaluation of activity was carried out by calculating, at different time intervals, the feeding ratio (FR) from the relationship between the consumed areas of treated disks (CTD) and control disks (CCD); for comparison purposes a FR₅₀ defined as the FR at a CCD of 50% was established. Some compounds exhibited activity at a 0.01 g/cm² dose (0.3 ppm). Structure-activity relationships are discussed     

Sources of fall armyworm,Spodoptera frugiperda (Lepidoptera: Noctuidae), kairomones eliciting host-finding behavior inCotesia (=Apanteles) marginivenitris (Hymenoptera: Braconidae)

Bioassay responses inCotesia marginiventris (Cresson) females to materials derived from fall armyworm (FAW) larvae,Spodoptera frugiperda (J. E. Smith), were most intense for frass and somewhat less intense for larval and pupal cutical materials, scales, exuviae, silk, and oral secretion, with FAW larval hemolymph eliciting only a slight response. The highest percentage of ovipositor probing was caused by frass (100%) and moth scales (90%). Various types of corn-leaf damage when assayed alone did not produce responses as intense as when assayed in combination with frass, cuticle material, and oral secretion. Parasitoid response was somewhat better to frass derived from FAW larvae feeding on corn and peanut leaves than from larvae feeding on the foliage of soybeans, Bermuda grass, cowpeas, or laboratory diet. Hexane and chloroform were better than methanol and water for extracting active material from FAW frass, and chloroform was the best of these solvents for extracting corn leaves. Serial dilutions of frass extracts resulted in a reduction in parasitoid response.This paper was submitted in partial fulfillment of the requirements for Doctor of Philosophy, Department of Entomology and Nematology, University of Florida, Gainesville.     

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.     

The influence of dietaryβ-carboline alkaloids on growth rate,food consumption,and food utilization of larvae ofSpodoptera exigua (Hubner)

-Carboline alkaloids are found worldwide in many plant families. Harman, harmine, and other simple -carboline alkaloids were tested for activity against a generalist phytophagous insect, the beet army worm [Spodoptera exigua (Hubner)]. Chronic dietary exposure tests (neonate to pupa) reveal potent antifeedant and possible toxic effects. Acute dietary exposure tests on fifth-instar larvae also demonstrate antifeedant activity.     

Flight activity ofHeliothis virescens (F.) females (Lepidoptera: Noctuidae) with reference to host-plant volatiles

Heliothis virescens (F.) females responded positively via upwind flight in laboratory assays to volatiles emitted from methyle chloride washes of fresh whole leaves of host plants including cotton, tobacco, and a weed species,Desmodium tortuosum (Swartz) de Candolle. Except forD. tortuosum, the response increased positively with dose; the steepest slope occurred with an extract of cotton squares (flower buds). Almost all of the moths that landed on the extract dispenser also oviposited. Moths simulated by extracts from cotton squares exhibited a full array of behaviors (upwind flight, contact with the dispenser, examination of the cloth substrate with antennae, and oviposition) expected of gravid individuals seeking sites to propagate the species.This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or the recommendation of its use by USDA.     

Attraction ofHeliothis virescens (F.) (Lepidoptera: Noctuidae) to volatiles from extracts of cotton flowers

Mated and virgin female and virgin male tobacco budworm moths,Heliothis virescens (F.), responded via directed upwind flight in wind-tunnel bioassays to volatiles from floral extracts of cotton,Gossypium hirsutum L. Significantly more male and female moths landed on cloth dispensers treated with a methylene chloride extract of debracted flowers than on control dispensers treated only with methylene chloride. Only mated females landed in significant numbers on the dispensers treated with extract of cotton squares, flowers (including bracts), or flower petals. After landing, most of the moths examined the dispensers by probing with their antennae, proboscis, and/or ovipositor.     

Effect of meliaceous seed extracts on growth and survival ofSpodoptera frugiperda (J.E. Smith)

Hexane and ethanol extracts of seeds from 10 plant species (including neem—Azadirachta indica A. Juss.) of the family Meliaceae were incorporated into artificial diet at various doses and fed to fall armyworm [Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)] larvae in nochoice tests. All produced significant mortality, reduced larval growth rate, increased time to pupation, or all three, at some concentration. The two highest doses of all of the ethanol extracts caused 100% mortality before pupation, but the hexane extracts tended to be less effective.Aglaia cordata Hiern. ethanol extract was as potent as the comparable neem seed extract at virtually all levels, and its hexane extract was active at much lower concentrations than the neem extract was. The sublethal effects (slower growth and increased time to pupation) were usually detectable at lower doses of extract than mortality was.Mention of firm or product names does not imply recommendation or endorsement by USDA over others not mentioned.     

Ovipositional response of tobacco budworm moths (Lepidoptera: Noctuidae) to cuticular labdanes and sucrose esters from the green leaves ofNicotiana glutinosa L. (Solanaceae)

Field plots of three accessions ofNicotiana glutinosa L. (Nicotiana species accessions 24, 24A, and 24B) at Oxford, North Carolina and Tifton, Georgia were heavily damaged by natural populations of tobacco budworms,Heliothis virescens (F.), during 1985–1989. Experiments in outdoor screen cages demonstrated that all accessions ofN. glutinosa were as prone to oviposition byH. virescens moths as was NC 2326, a commercial cultivar of flue-cured tobacco,N. tabacum L. However, in greenhouse experiments, tobacco budworm larvae did not survive or grow as well when placed on plants ofN. glutinosa as they did when placed on plants of NC 2326. Four labdane diterpenes (manool, 2-hydroxymanool, a mixture of sclareols, and labda-13-ene-8,15-diol [labdenediol]) and two sucrose ester fractions (2,3,4-tri-O-acyl-3-O-acetyl-sucrose [G-SE-I] and 2,3,4,-tri-O-acyl-sucrose [G-SE-II]) were isolated from green leaves of the three accessions ofN. glutinosa. These components were bioassayed for their effects on the ovipositional behavior of tobacco budworm moths using small screen cages in a greenhouse at Oxford, North Carolina. Labdenediol, manool, and both sucrose ester fractions stimulated tobacco budworm moths to oviposit on a tobacco budworm-resistant Tobacco Introduction, TI 1112 (PI 124166), when these materials were sprayed onto a leaf.This article reports the results of research only. Mention of a proprietary product does not constitute endorsement or recommendation for its use by USDA, ARS, or by the North Carolina Agricultural Research Service.