Thyridopteryx Ephemeraeformis Research Articles

Susceptibility of Honeylocust Cultivars to Thyronectria austro-americana and Response of Agrilus Borers and Bagworms to Infected and Non-infected Trees

Abstract Six cultivars of honeylocust, Gleditsia triacanthos L., were inoculated with the canker fungus Thyronectria austro-americana to test the hypothesis that trees stressed by Thyronectria are rendered more attractive to wood borers, or more suitable as hosts for the bag worm, Thyridopteryx ephemeraeformis (Lepidoptera: Psychidae). Relative susceptibility of cultivars to the fungus, and seasonal flight activity of associated borers were also monitored. Cultivars ‘Sunburst,’ ‘Shademaster,’ and ‘Rubylace’ developed the largest cankers; ‘Imperial’ was variable, and ‘Skyline’ and ‘Trueshade’ were somewhat less susceptible. Adults of four species of Agrilus borers (Coleoptera: Buprestidae) were abundant on honeylocust. Beetles were active from late May until August. Adult borers were attracted equally to infected and non-infected trees, but borers apparently failed to colonize trees of either type. Levels of soluble protein were higher in foliage of diseased trees, but growth and survival of bagworms were similar for both treatments. This study did not support a close relationship between Thyronectria canker disease of honeylocust and predisposition to wood borers, at least on relatively vigorous hosts.

Suitability of Juniper Cultivars for Survival and Growth of the Bagworm

Abstract Relative suitability of 23 cultivars of juniper (Juniperus spp.) for growth and survival of the bagworm, Thyridopteryx ephemeraeformis (Haworth) was evaluated in laboratory and field experiments. Weight gain, developmental rate, and survival of bagworms differed significantly among groups of larvae fed foliage from different cultivars. By these criteria, cultivars ‘Expansa’ and ‘Hibemica’ were most unsuitable for survival and development of bagworms, whereas ‘Broadmoor’ and ‘Emerald Isle’ were consistently among the most suitable cultivars. This study suggests that use of certain juniper cultivars may be useful in managing this perennial insect pest in urban landscapes.

Nutritional performance of first and penultimate‐final Instar bagworm larvae on two unrelated hosts as influenced by host of origin

AbstractNutritional performance of early and late instar bagworm (Thyridopteryx ephemeraeformis Haworth) larvae was investigated as a function of host of origin and host type, using two taxonomically distant wild hosts, Salix nigra (Marshall) and Juniperus virginiana (L.). First instar growth and survival were higher on S. nigra; overall performance was similar on the two hosts in penultimate‐final instars. There was no evidence for host associated differentiation with respect to nutritional performance. There were, however, significant genotype & environment interactions for several characters studied, suggesting that the potential for host associated differentiation exists.

Biotic Indicators of Host Preference by the Bagworm (Lepidoptera: Psychidae)

Mortality, bag length, and larval head capsule width of the bagworm, Thyridopteryx ephemeraeformis (Haworth), were examined in greenhouse tests as indicators of host preference for deciduous and coniferous hosts, both as donor and recipient host. Neonate larvae reared from eggs collected from deciduous and evergreen hosts were placed on selected tree species and allowed to feed for 30 d. Arborvitae ( Thuja occidentalis L.) and black locust ( Robinia pseudoacacia L.) had lower mortalities compared with eastern white pine ( Pinus strobus L.), honeylocust ( Gleditsia triacanthos L.), and American sycamore ( Plantoides occidentalis L.). Original host had no specific effect on mortality. Significantly longer bags and a corresponding higher frequency of older instars were observed when bagworm originated from black locust compared with other hosts. Compared with other sources, larvae obtained from arborvitae consistently produced longer bags on each host species. This is the first demonstration of a significant difference in bagworm development for each of the biotic factors studied, and the first identification of black locust as a superior host for bagworm. The effect of host shape on rate of infestation is discussed.

Feeding preferences and their modification in early and late instar larvae of the bagworm,Thyridopteryx ephemeraeformis (Lepidoptera: Psychidae)

Feeding preferences in naive first instar and penultimate-final instar bagworm (Thyridopteryx ephemeraeformis)larvae were investigated using two choice tests. Naive first instar larvae showed a general (though not exclusive) preference for black willow (Salix nigra)over other hosts tested, regardless of the host of origin. Penultimate-final instar larvae showed strong preferences for the previous rearing host, suggesting induction of host preference; there was no evidence of host origin effects. The ability to discriminate among hosts is important if it is actually used to make host choices based on host quality. In bagworms, where host choices (if any) must be made by larvae in habitats where several hosts are often present, host discriminatory ability is likely important.

Introduction and North American Establishment of Coccygomimus disparis (Hymenoptera: Ichneumonidae), a Polyphagous Pupal Parasite of Lepidoptera, Including Gypsy Moth

Recoveries of Coccygomimus disparis (Viereck) from pupae of gypsy moth, Lymantria dispar (L.), in Pennsylvania, Maryland, New Jersey, Massachusetts, Virginia, Vermont, New York, Nebraska, and Ontario, Canada, indicate that this Palearctic species is now well established in North America. This represents the first successful establishment of a natural enemy of gypsy moth in North America in nearly 50 yr. Levels of pupal parasitism in gypsy moth average 1.9% (maximum 13%). Historical records indicate C. disparis was intentionally imported from India (1972), Japan (1976), and Korea (1984). Laboratory rearing resulted in the eventual release of more than 819,012 individuals liberated in 16 states. Details on the biology of this wasp, its foreign collection, introduction, release, and recovery (first in North America in 1978) are documented. Recovery from Thyridopteryx ephemeraeformis (Haworth) (Psychidae) and Malacosoma americanum (F.) (Lasiocampidae) in New Jersey and Dioryctria auranticella (Grote) (Pyralidae) from Nebraska, as well as host data from outside the United States, indicates that C. disparis is not specific to gypsy moth and should be searched for in other forest or shade tree Lepidoptera. Recent collections of M. americanum in New Jersey showed 20.6% parasitism. Overall effectiveness as a biological control agent against the gypsy moth or other hosts remains uncertain but promising.

Economic and Aesthetic Injury Levels and Thresholds for Insect Pests of Ornamental Plants

This article reviews decision-making considerations that apply to the management of insect pests of ornamental plants. In particular we estimate a modified Economic Injury Level (EIL) for the bagworm, Thyridopteryx ephemeraeformis (Haworth), attacking American arborvitae, Thuja occidentalis under retail nursery conditions. Under these circumstances, the EIL was found to be only about four first instar larvae per 4 ft tree. This confirms earlier suppositions concerning the low tolerance for pests causing aesthetic injury. In addition, we briefly examine the concepts of Aesthetic Injury Levels (AIL) and Aesthetic Thresholds and illustrate how these may be estimated for pests causing aesthetic injury.

Inverse Density-Dependent Parasitism of the Bagworm, Thyridopteryx ephemeraeformis (Lepidoptera: Psychidae)

This paper reports the results of a controlled manipulative experiment with the bagworm, Thyridopteryx ephemeraeformis (Haworth), on eastern redcedar, juniperus virginiana L., to determine whether parasitism is density-dependent. Parasitoid foraging behavior indicated that two spatial scales were appropriate: individual trees and small patches of trees. Percentage of parasitism by Itoplectis conquisitor (Say) declined significantly as the density of female bagworms on individual trees increased. Although mathematically possible, this inverse density-dependent response appears too “vague” to promote the stability of the bagworm- I. conquisitor system. Other factors that may be involved in the regulation or control of the bagworm are discussed.

The influence of host distribution, sex, and size on the level of parasitism by Itoplectis conquisitor (Hymenoptera: Ichneumonidae)

Abstract. 1. Parasitism of the bagworm, Thyridopteryx ephemeraeformis Haw. (Lepidoptera: Psychidae), on red cedar was studied at Manassas, Va., U.S.A.2. Fifteen parasitoids, five of which were hyperparasitoids, attacked the pupal stage of the bagworm. The Ichneumonid Itoplectis conquisitor alone accounted for 58% of the parasitized bagworms.3. Parasitism by I conquisitor (Say) was inversely related to host size, but independent of host distribution within a tree. Male bagworms experienced disproportionately higher levels of parasitism than females. We conclude that it is small size that renders bagworms susceptible to parasitism rather than sex per se.4. Ovipositor lengths of I.conquisitor were insufficient to penetrate the larger bagworm hosts (>57 mm); and in fact, as bagworm size increased, the proportion of the I.conquisitor population capable of penetrating the pupa declined abruptly. We suggest that the mechanical difficulties with oviposition, and perhaps the defensive capabilities of larger hosts, are responsible for the relationship between host size and per cent parasitism.5. I.conquisitor could be an important selective agent for bagworm size at pupation, but it is not likely to act as a significant control agent of population density.

Modified Thoracic Epithelium of the Bagworm (Lepidoptera: Psychidae): Site of Pheromone Production in Adult Females

The site of synthesis and release of R-1-methylbutyl decanoate, the sex pheromone of the female bagworm, Thyridopteryx ephemeraeformis (Haworth), is unusual in Lepidoptera. Large amounts of pheromone were extracted and verified by gas chromatography from deciduous setae from ventral thoraces of calling females. Surface features of this part of the thorax, as revealed by scanning electron microscopy, include linear arrays of cuticular excrescences free of setal sockets. Within the excrescences of the ventral thorax and first abdominal segment are swollen cuboidal epithelial cells with enlarged nuclei. These large epithelial cells resemble cells responsible for pheromone synthesis in abdomens of other insects. This is the first report of the localization of a sex pheromone gland in modified epithelial cells of the adult thorax and first abdominal segment of a Nearctic lepidopteran species.

WITHIN-CROWN DISTRIBUIONS OF MALE AND FEMALE BAGWORM (LEPIDOPTERA: PSYCHIDAE) PUPAE ON JUNIPER AS AFFECTED BY HOST DEFOLIATION

AbstractWe examined the within-crown distributions of male and female bagworm, Thyridopteryx ephemeraeformis (Haworth), pupae on Juniperus virginiana L. as a function of prior defoliation. This was to evaluate the hypothesis that the differential movement of females to the upper crown before pupation would be strongest on heavily defoliated trees. Differential stratification of the sexes occurred irrespective of degree of defoliation, and despite the fact that competition, as evidenced by higher mortality of pupae and reduced weight of egg masses, was apparently greatest at the top of moderately and severely defoliated hosts. There was no relationship between height of pupation and risk of parasitism for either sex. Female larvae were ca. 4-fold more likely than males to abandon a low-lying host upon which they had fed and to ascend the trunks of nearby trees before pupating. Enhancement of larval dispersal by females is the most plausible explanation for the stratified distribution of bagworm pupae within trees.

Consumer Attitudes Toward the Defoliation of American Arborvitae, Thuja occidentalis, by Bagworm, Thyridopteryx ephemeraeformis

A group of 93 retail nursery customers were surveyed to determine their attitudes toward defoliation of American arborvitae, Thuja occidentalis L., caused by the bagworm, Thyridopteryx ephemeraeformis (Haworth). More than half of the customers surveyed perceived plants with 4% of the leaf area missing or discolored as damaged. The proportion of customers who refused to buy a plant corresponded closely (r = 0.98, p < .0001) with the proportion of those who perceived the plant as damaged.

Temperature-dependent Model for Predicting Larval Emergence of the Bagworm, Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera: Psychidae)

A temperature-dependent model was developed to predict spring emergence of bagworm, Thyridopteryx ephemeraeformis (Haworth), larvae. Rearing of eggs collected weekly from October through May and then incubated at 26.1°C showed that embryonic synchrony occurred by late January, when variation in larval emergence periods reached a minimum. There was a linear relationship ( r 2 = 0.989) between development rate and temperature between 16.7 and 26.1°C for eggs collected in late January and early February. Larvae required heat accumulations of approximately 380 degree-days (DD) for first median day emergence and 572 DD for last emergence. The average deviation between predicted and observed dates of first emergence was less than one day, but the predicted time for last emergence was greater than the observed time by 5 days or more.

Respiration and cold-hardiness in overwintering eggs of the bagworm moth, Thyridopteryx ephemeraeformis (Lepidoptera: Psychidae)

1. 1. Respiration rates of eggs of the bagworm moth, Thyridopteryx ephemeraeformis (Haworth) declined from October until March. Rates increased in the spring with the resumption of embryogenesis. 2. 2. Respiratory Q 10 values (2–12°C) varied from 3.2 to 4.5. Lipid was utilized primarily in respiration. 3. 3. Mean supercooling points (SCP) decreased from −26 to −30°C in autumn, remained low during winter and increased in the spring. 4. 4. The autumn depression in SCP was considered important for survival. 5. 5. Substantial mortality was predicted during the winter of 1984–1985. 6. 6. Glycerol and at least one other polyol were detected in eggs.

Salient Vestiture and Morphological Characters of the Pharate Female Bagworm, Thyridopteryx ephemeraeformis (Lepidoptera: Psychidae)

The pharate adult female bagworm, Thyridopteryx ephemeraeformis (Haworth), encased in the pupal shell in its larval bag, has a previously unreported distinctive vestiture that is important in reproduction as well as other surface features that may be important taxonomically. Lateral and ventral surfaces of the thorax, and anterior surface of abdominal segment I have dense elliptical tufts of loosely attached amber-colored hair-scales that dispense pheromone. Abdominal segment VII and the posterior part of VI have a dense tuft of upright hair-scales that are persistent unless the female is mated. Anterior scales of the thorax and posterior hair-scales of segment VII are hexagonal, possess a lumen, and arise from uniform cuticular sockets. Posterior scales are dense, uniformly distributed, and lack an elliptical twist. The opisthognathous head is devoid of scales and is reduced. Anterior tentorial pits are prominent. Compound eyes are formed from two separate or contiguous groups of loosely associated ommatidia. A dense band of upright obovate lamellar scales with irregular sockets encircles abdominal segments I to VI and are shed and compressed by the female to form a plug protecting the eggs in the pupal case.

AERIAL DISPERSAL BEHAVIOR OF LARVAL BAGWORMS, THYRIDOPTERYX EPHEMERAEFORMIS (LEPIDOPTERA: PSYCHIDAE)

AbstractSeasonal and daily patterns of ballooning, and behavioral processes involved in aerial dispersal of the bagworm, Thyridopteryx ephemeraeformis (Haworth), were studied on Juniperus virginiana L. in Kentucky. The aerial dispersal period began in mid-May 1983 and lasted ca. 1 month. About 75% of dispersing larvae ballooned after making a bag. Settling velocities were determined for larvae with and without bags and trailing varying lengths of silk; a model was then developed that predicts dispersal distance for a particular wind speed and departure height. Most aerial dispersal is probably short-range. The bag reduced potential dispersal distance, but larvae with bags survived ca. 2 days longer than those without bags when exposed to abiotic factors off of a host. Larvae without bags ballooned mostly in morning, whereas 80% of the larvae dispersing with a bag ballooned in the afternoon. These patterns may be related to the diel periodicity of emergence of neonate larvae from old female bags, and the subsequent behavior of 1st instars prior to dispersal. A large proportion of each cohort emigrates regardless of host condition.

Suppression of female bagworm, Thyridopteryx ephemeraeformis reproduction potential with its sex pheromone, 1‐methylbutyl decanoate

AbstractMating of the female bagworm, Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera: Psychidae) on host trees treated with the racemate of the species' female sex pheromone, 1‐methylbutyl decanoate, was suppressed by 87% in the field. The suppressive effect of the pheromone was independent of insect population density when it was evaporated from female‐infested trees at 712 (± 29; S.E.) mg/tree/3 day from a 488 cm × 0.63 cm polyvinylchloride laminated tape. However, evaporation of pheromone at a lower rate did not suppress mating. Observations of adult male behavior in the vicinity of the pheromone‐impregnated tape revealed that males were attracted to the tape and that they made copulatory thrusts toward the tape and any object touching the tape. These observations and analyses of the pheromone titers of individual females showed that males can respond to a wide range of pheromone concentrations. Indications are that the mechanism of mating suppression probably involved male sensory adaptation or central nervous habituation to the synthetic 1‐methylbutyl decanoate and that the compound, evaporated from host trees, could be useful as a plant protectant against the bagworm.RésuméSuppression de la reproduction de Thyridopteryx ephemeraeformis grâce à sa phéromone sexuelle, le 1‐méthylbutyl décanoateLes accouplements des femelles de Thyridopteryx ephemeraeformis Haworth (Lep. Psychidae) ont été réduits de 87% sur des arbres hôtes traités dans la nature par des racémates du 1‐méthylburyldécanoate, la phéromone sexuelle femelle de cette espèce. Lorsque la phéromone s'évapore à partir d'un ruban de 488 cm sur 0,63 de chlorure de polyvinyle portant 712 (±29 S.E.) mg, par arbre pendant 3 jours, l'efficacité était indépendante de la densité de population de l'insecte. Cependant, l'évaporation de la phéromone à une plus faible concentration était sans effet. L'observation du comportement des mâles au voisinage des rubans imprégnés de phéromone a montré qu'ils étaient attirés par le ruban et qu'ils tentaient de s'accoupler avec le ruban et tout objet à son contact. Ces observations et les analyses des concentrations en phéromones des femelles ont montré que les âles pouvaient répondre à une gamme étendue de concentrations en phéromone. Il y a des indices que le mécanisme de suppression de l'accouplement implique une adaptation sensorielle du mâle ou une accoutumance du système nerveux central au 1‐méthylbutyl décanoate synthétique et que ce composé s'évaporant sur les arbres hôtes, pourrait être utilisable pour protéger efficacemment contre T. ephemeraeformis.

Selected Effects of Sublethal Dosages of Three Insecticides on the Bagworm

A survey was made under field conditions of the effects of sublethal dosage by ingestion of bagworm larvae, Thyridopteryx ephemeraeformis placed on diazinon, carbaryl, or toxaphene treated juniper. Low dosage ingestion did not affect survival, egg number, pupation duration, or emergence patterns. Test populations on diazinon treated trees completed development through the pupation stage in significantly higher numbers. Treatments with toxaphene resulted in significantly larger egg size but treatment with carbaryl produced a significant decrease in egg size.

Effective controlled-release dispensers for the pheromone of the bagworm. release rate vs. trap catch

The racemate of the sex attractant pheromone of the bagworm, Thyridopteryx ephemerae-formis (Haworth), was formulated in controlled-release, plastic laminated dispensers for laboratory and field evaluation in an effort to develop an effective, long-lasting bait for monitor traps. Five variations in the plastic membrane used for the outer layers were tested. Dispensers were aged outdoors for 1 to 8 weeks before ths flight season of the moth. The lure contents of unaged and aged dispensers were measured chromatographically to determine the pheromone release rate from each dispenser as a function of time. Field efficacy of the dispensers in attracting moths to traps was determined in a single trap test during peak moth flight in September 1982 in Maryland. Each of the 5 laminates was found to release pheromone by approximately first-order kinetics, resulting in progressively lower release rates after successive periods of aging. The dispensers made from 16-mil poly vinyl chloride (PVC) film containing polymeric plasticizers were still attractive after 8 weeks of aging, while those made from 3-, 6-, and 16-mil PVC film containing monomeric plasticizers were effective for shorter periods. The 3-mil acrylic film (a copolymer of acrylates and methacrylates) released lure too slowly for high activity. The insect catch increased with progressively higher rates of release from 5 to 2000 μg of racemic pheromone per day. A dispenser containing a higher initial amount of lure would be expected to give higher catches and remain effective for a longer time in the field.

Differential stratification, movement and parasitism of sexes of the bagworm, Thyridopteryx ephemeraeformis on redcedar

Abstract. 1. Male and female bagworm larvae develop and pupate at different heights on redcedar trees.2. Habitat segregation by height of male and female bagworms is apparent by the third instar, and results in part from differential movement of male and female larvae on redcedar foliage during their development. Females gradually ascend the crown, whereas males remain at the same height on the tree.3. Parasitism of male bagworm pupae was greater than for female pupae. Pupal parasitism is heaviest in the bottom of redcedar trees, where most male bagworms pupate.4. Several hypotheses are offered concerning the origin and maintenance of differential habitat utilization by male and female bagworms, despite apparently strong selection against males pupating low in the crowns of redcedar.