Orgyia Leucostigma Research Articles

PEST MANAGEMENT OF DOUGLAS-FIR TUSSOCK MOTH (LEPIDOPTERA: LYMANTRIIDAE): PREVENTION OF AN OUTBREAK THROUGH EARLY TREATMENT WITH A NUCLEAR POLYHEDROSIS VIRUS BY GROUND AND AERIAL APPLICATIONS

AbstractTwo different application methods were tested using a nuclear polyhedrosis virus as a control agent at an early stage in the outbreak cycle of Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), in south central British Columbia in 1981. The virus, which often leads to the development of an epizootic late in the outbreak cycle, was propagated in whitemarked tussock moth, Orgyia leucostigma (J. E. Smith). A helicopter fitted with a boom and nozzle was used for treating four plots (total area 19.8 ha) at a dosage of 2.2 × 1011 polyhedral inclusion bodies (PIB) in an emitted volume of 11.3 L ha−1. Five to eight weeks after spraying, microscopic examination of live larvae showed that 77 to 100% were infected. In ground-spray applications of two other plots, a modified orchard-type sprayer was used to apply 2.4 × 1010 PIB in a volume of 4.5 L per tree. Microscopic diagnosis of live larvae at 8 weeks post-spray revealed 83 and 85% infection.In autumn 1981, no egg masses could be found in the plots treated earlier that year and no larvae were found on the sample trees in 1982 or 1983. The treatment was effective over a range of initial mean larval densities of 41 to 206 m−2 of foliage. At the same time, populations in nearby untreated areas increased in 1982. Little foliage protection was obtained the year of application due to the lengthy virus incubation period, but the trees recovered quickly when populations disappeared due to the virus epizootic.

Suitability of the White-Marked Tussock Moth (Lepidoptera: Lymantriidae) as an Alternate Host for the Imported Gypsy Moth (Lepidoptera: Lymantriidae) Parasite, Rogas lymantriae Watanabe (Hymenoptera: Braconidae)

In choice experiments in the laboratory, Rogas lymantriae Watanabe preferred Lymantria dispar (L.) larvae over Orgyia leucostigma J. E. Smith, and development from oviposition to mummification was significantly longer in O. leucostigma than in L. dispar. There were no differences in sex ratio of R. lymantriae reared in the different hosts; hence, O. leucostigma is a suitable alternate host for R. lymantriae. Despite being reared on L. dispar in the laboratory for over 50 generations, R. lymantriae parasitized L. dispar in the field; future releases to establish R. lymantriae should be made where L. dispar and O. leucostigma occur together.

Replication and serial passage of a singly enveloped baculovirus of Orgyia leucostigma in homologous cell lines.

A singly enveloped nuclear polyhedrosis virus (SNPV) of the white-marked tussock moth, Orgyia leucostigma, was successfully grown in four continuous cell lines developed from minced neonate larvae of this insect. Level of infection in two cell lines, IPRI-OL-12 and IPRI-OL-13, was 65-90%, but in the other two, IPRI-OL-4 and IPRI-OL-9, it was about 3%. Polyhedral inclusion bodies (PIBs) appeared in the nuclei of cells within 24 h postinoculation. Cytopathological changes and morphogenesis of the virus, as revealed by light and electron microscopy, were in general typical of an SNPV. However, some of the PIBs contained very few virions, and some were fractured. Rate zonal centrifugation of alkali-released occluded virions further confirmed the singly enveloped characteristics of the virus. The SNPV was serially passaged 60 times each in OL-12 and OL-13 cells. Percentage infected cells and PIB production stayed generally high throughout serial passaging in OL-13 cells, but declined sharply after the 41st passage in OL-12 cells. PIBs from the 4th passage of the virus in OL-12 cells were tested and found to be pathogenic to O. leucostigma larvae.

Replication and serial passage of a multicapsid nuclear polyhedrosis virus of Orgyia pseudotsugata (Lepidoptera: Lymantriidae) in continuous insect cell lines

A multicapsid nuclear polyhedrosis virus (MNPV) of the Douglas-fir tussock moth, Orgyia pseudotsugata, propagated in larvae of the white-marked tussock moth, O. leucostigma, was successfully grown in two continuous cell lines developed from minced neonate larvae of O. leucostigma. Polyhedral inclusion bodies (PIBs) appeared in the nuclei of cells within 24 h after inoculation. Cytopathological changes, as revealed by light and electron microscopy, were typical of an MNPV. The virus has been passaged in the cell cultures 55 times. The level of infection during passaging has varied from 15 to 98% of the cells, and the number of PIBs per cell from 10 to 40. The PIBs from the fourth passage of the virus in cell cultures were almost as pathogenic to O. leucostigma larvae as the PIBs produced in larvae.

Mating Behavior of the Whitemarked Tussock Moth1 and Role of Female Scales in Releasing Male Copulatory Attempts

The short-range precopulatory behavior of the whitemarked tussock moth, Orgyia leucostigma (J. E. Smith), was observed in the laboratory. Male copulatory behavior is released by tarsal contact with the female's body scales. In the absence of female scales, the male's behavior is significantly altered and he has difficulty orienting properly to the female. As a result the male takes twice as long to initiate a copulatory attempt and takes twice as long to achieve copulation. In addition, the percentage of encounters that lead to at least one copulatory attempt is significantly reduced. Plasticene® models coated with female tussock moth scales elicited normal courtship and copulatory behavior as did freeze-dried tussock moth females with scales intact. Plasticene models without scales or coated with scales from the spruce budworm, Choristoneura fumiferana (Clemens), elicited abnormal mating behavior and significantly reduced copulatory responses. It is not clear whether chemical or mechanical characteristics of the female scales release male copulatory behavior.

DISRUPTION OF PHEROMONE COMMUNICATION OF THE RUSTY TUSSOCK MOTH, ORGYIA ANTIQUA (LEPIDOPTERA: LYMANTRIIDAE), WITH (Z)-6-HENEICOSEN-11-ONE

Tussock moths of the family Lymantriidae are an important group of forest defoliators that characteristically have periodic outbreaks. The sex pheromone of the female Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), has been identified as (Z)-6-heneicosen-11-one (Smith et al. 1975) and shown to be sexually stimulating to males of seven tussock moth species in two genera, Orgyia and Dasychira (Daterman et al. 1976; Grant 1977). Laboratory tests demonstrated that this compound could disrupt mating of both the whitemarked tussock moth,O. leucostigma (J.E. Smith), and rusty tussock moth, O. antiqua (L.), when the adults were maintained in an atmosphere containing the chemical (Grant and Frech 1976). Subsequently field tests in small plots treated with the same material released into the atmosphere at a rate equivalent to 20-50 mg/ha/day demonstrated that pheromone communication of whitemarked tussock moths and a conifer-feeding tussock moth, Dasychira plagiata (Walker), could be disrupted in their natural habitat (Grant 1978). Similar disruption was obtained with field populations of the Douglas-fir tussock moth (Sower and Daterman 1977). The present report describes the disruptive effects of (Z)-6-heneicosen-11-one in the field on the pheromone communication of another species, the rusty tussock moth.

Field Trials on Disruption of Pheromone Communication of Tussock Moths1

Pheromone disruption experiments were carried out by releasing and recapturing laboratory-reared, whitemarked tussock moth (WMT), Orgyia leucostigma (J. E. Smith), males in small plots (324 m2). One plot was treated with (Z)-6-heneicosen-11-one, the Douglas-fir tussock moth pheromone, released from planchet evaporators at an estimated rate of 4.4 mg/plot/day (= ca. 140 mg/ha/day). In 14 replicates, 50% of the 864 released males in the untreated plot were recaptured but only 1.2% of 869 released males in the treated plot were recaptured. The average disruption was 97.6%. The same chemical was effective in disrupting pheromone communication of feral populations of WMT and pine tussock moth (PTM), Dasychira Plagiala (Walker), in similar small plot tests. Planchet evaporators, releasing the chemical at ca. 4.4 mg/plot/day, caused 92–100% disruption of PTM and 96–100% disruption of WMT. Commercially prepared hollow fiber dispensers, releasing pheromone at rates of 0.7, 1.2 and 1.6 mg/plot/day (= ca. 20, 40 and 50 mg/ha/day, respectively), caused 65–96% disruption of PTM and 76–92% disruption of WMT. (Z)-6-heneicosen-ll-one offers promise for pheromone communication disruption of several tussock moth species.

Apple, White-Marked Tussock Moth: Effect of Pesticides in the Laboratory and Field, 1977

Abstract The recommended rates of each pesticide were mixed with water in 1L containers in the laboratory. Styrofoam cups (270 ml) containing apple cuttings with all but 4 leaves removed were dipped in each mixture. Larvae in the fourth and fifth instar were immediately added to the cups. Each treat-ment was replicated 4 times with 10 larvae per cup. Mortality readings were taken at 24 h. intergals for 5 days. Larvae were considered dead only when they did not move when poked with a probe.

Potential Alternate Hosts of the Gypsy Moth 1 Parasite Apanteles porthetriae 234

Apanteles porthetriae Mues. and Apanteles liparidis (Bouche) are important regulating agents of the gypsy moth, Lymantria dispar (L.), throughout their native range. The failure of these parasites to become established in the U.S. has been attributed to their inability to find suitable alternate hosts. This study examined the status of native Lepidoptera as potential alternate hosts. A. porthetriae successfully developed in 3 native species: the white-marked tussock moth, Orgyia leucostigma (J. E. Smith), the fall webworm, Hyphantria cunea (Drury), and the yellow woolly bear, Diacrisia virginica (F.). A. liparidis did not develop in any native species. The possibility of the future establishment of A. porthetriae is discussed, emphasizing the importance of O. leucostigma as an alternate host.

Development and ultrastructure of cells of the sex pheromone gland in the white-marked tussock moth, Orgyia leucostigma (J. E. Smith) (Lepidoptera: Lymantriidae)

In pharate adults of female Orgyia leucostigma the pheromone gland cells are columnar. They change to goblet-shaped cells during the day preceding emergence. Concurrently, endocuticular extensions follow the contour of the neck of each goblet cell. Until 12–24 hr following emergence of the adult female, gland cell cytoplasm contains short profiles of rough endoplasmic reticulum and free ribosomes. In cells from 1-, 2- and 3-day-old virgin and 1-day-old mated females extensive well-organized smooth cisternal and rough endoplasmic reticulum predominate. Arrays of membranes, forming unusual organelles are located near the nuclei. They are associated with the Golgi complexes, rough endoplasmic reticulum and microbodies. Microvilli are variable in length and sometimes absent. Cuticular ultrastructure is the same as that of the pharate adult, and is not affected by surface extraction with hexane.

Susceptibility of the spruce budworm, Choristoneura fumiferana, and the white-marked tussock moth, Orgyia leucostigmata, to Bacillus thuringiensis: Chemical insecticide combinations

Bacillus thuringiensis mixed with the organophosphate insecticides, fenitrothion (Sumithion), Gardona ®, and Orthene ®, or the synthetic pyrethroid, SBP 1382, was incorporated into synthetic diet and fed larvae of the spruce budworm, Choristoneura fumiferana, and the white-marked tussock moth, Orgyia leucostigma. Mortality was highest when larvae were fed combinations of low concentrations of the insecticides and low to moderate concentrations of the pathogen. The data indicated that applications of a B. thuringiensis dosage expected to produce about 45% mortality of third and fourth instar larvae of the spruce budworm combined with a dosage of fenitrothion causing about 40% mortality or a dosage of Orthene causing from 5 to 25% mortality should result in low budworm survival. With a B. thuringiensis dosage causing 20–60% mortality combined with a fenitrothion dosage causing 15–50% mortality or a sublethal dosage of Gardona, a low survival rate of young white-marked tussock moth larvae may be expected.

Tussock Moths:1 Pheromone Cross Stimulation, Calling Behavior, and Effect of Hybridization2

Adult crosses, pheromone extract bioassays, and electroantennogram (EAG) tests suggest that 3 species of tussock moth, Hemerocampa leucostigma (J. E. Smith), H. pseudotsugata McDunnough, and H. vetusta (Boisduval), have similar sex pheromones. The same tests also indicate that hybrids from the cross female H. pseudotsugata × male H. leucostigma possess a sex pheromone system more like the female parent than the male parent; that is, the sex pheromone of the female hybrid was like that of female H. pseudotsugata and the pheromone receptors of the male hybrid were like those of male H. pseudotsugata. On the other hand, the calling periodicity of female hybrids displayed traits of both parents.

Dosage-mortality studies with commercial Bacillus thuringiensis sprayed in a modified Potter's tower against some forest insects

Dosage-mortality tests were carried out with commercial Bacillus thuringiensis (B.T.) (Dipel) ® against various instars of the spruce budworm, Choristoneura fumiferana, the white-marked and Douglas fir tussock moths, Hemerocampa leucostigmata and Orgyia pseudotsugata, and the gypsy moth, Porthetria dispar. Dipel was applied as a dilute (10 −2) molasses suspension onto artificial diet surface in a spray tower designed to simulate aerial application. Probit analysis of the results showed that LD 50s expressed both in terms of gallons deposited per acre and as spores and crystals deposited per cm 2 increased with larval age for all species. The spruce budworm was the most sensitive to the bacteria, followed in decreasing order of sensitivity by the white-marked tussock moth, Douglas fir tussock moth, and the gypsy moth. The mean slopes for all instars of the four species were 1.6, 3.1, 2.6, and 2.2, respectively, indicating that precision-wise, the assay of B.T. on artificial medium was good. The relatively low slope for spruce budworm is explained by its peculiar feeding habit. Among all species tested, bacteria-treated larvae gained weight at a considerably reduced rate compared with untreated ones. Reduction in weight resulting from lowered feeding activity intensified as dosage rates increased. The implication of this in terms of mortality assessments in microbial control operations is discussed. It is suggested that 0.02 gallon (4 × 10 6 International Units) of Dipel Molasses deposited per acre may achieve economic control of fourth- to sixth-instar budworm and first-to second-instar gypsy moths. A deposit rate for second- to fifth-instar white-marked or Douglas fir tussock moths appears to be in the vicinity of 0.01 gallon (2 × 10 6 IU) per acre.

Specificity of serological cross-reactions between insect viruses and ribosomes

Ribosomes from guinea pig liver, Cavia cobaya; frog liver, Rana pipiens; midgut of the silkworm, Bombyx mori; an earthworm, Lumbricus terrestris; a bacterium, Escherichia coli; a fungus of the genus Lactarius; and also the synthetic polyribonucleotides poly A and poly U were serologically compared with the cytoplasmic polyhedrosis viruses from Bombyx mori, the tent caterpillar Malacosoma disstria, and the tussock moth Orgyia leucostigma. The method of double diffusion on cellulose acetate membranes was used. Extensive cross-reactivity was observed, and it is attributed to the ribose phosphate backbone of RNA as a common antigen.

The effect of 137Cs radiation on growth, development, and mortality of the larvae of the tussock moth, Hemerocampa leucostigma

Larvae and pupae of Hemerocampa leucostigma were irradiated in a 137Cs Radcell and observed for effects on growth, development, and mortality. Irradiated larvae were half of control weight 10 days postradiation. Although pupae were extremely resistant, relatively low doses to larvae prevented emergence. LD 100 of first instars was 30 kr, while that of third instars was 85 kr. No delay in median time to pupation was noted.

RNA in midgut of tussock moth, Orgyia leucostigma, infected with cytoplasmic-polyhedrosis virus.

The RNA synthesis in the midgut of the tussock moth, Orgyia leucostigma, infected with cytoplasmic-polyhedrosis virus has been studied in the presence of actinomycin D. Although actinomycin D at a concentration of 2 μg/larva does inhibit the cellular RNA synthesis, virus-specific RNA can be still synthesized in the infected midgut. In these conditions, two species of virus-specific RNA are found; one is RNase-sensitive and the other is resistant. The enzyme-sensitive RNA may be single-stranded and consists of at least two components which have sedimentation rates of 22 and 15 S, while the resistant RNA is probably double-stranded viral progeny RNA. Under the same condition, however, virion formation is inhibited about 63%.

Properties of RNA from cytoplasmic-polyhedrosis virus of the white-marked tussock moth, Orgyia leucostigma

When the genome RNA is extracted from the cytoplasmic-polyhedrosis virus of the white-marked tussock moth, Orgyia leucostigma, by the phenol method, it has two components with sedimentation rates of about 15 and 12 S. Their base composition includes adenine and uracil as well as guanine and cytosine. The guanine + cytosine content was 41.2%. Melting temperature of the RNA was about 80°C in a solution containing 0.0015 m NACl-0.00015 m sodium citrate. Most of the RNA was found to be resistant to ribonuclease digestion; some of it was partially sensitive and was presumed to be single-stranded. After enzyme treatment, the 15 and 12 S components of the genome sedimented at about 9 S. From these findings it is proposed that viral genome RNA from cytoplasmic-polyhedrosis virus is double-stranded.

Detection of natural infection by cytoplasmic polyhedrosis virus (CPV) occurring in midgut cells of the white-marked tussock moth larvae

Detection of natural infection by cytoplasmic polyhedrosis virus (CPV) occurring in midgut cells of the white-marked tussock moth larvae

The isolation of cytoplasmic polyhedrosis virus from the white-marked tussock moth, Orgyia leucostigma (Smith).

The procedure for isolating and purifying free and occluded cytoplasmic polyhedrosis virions was improved. The virions are resistant to the enzymes RNase, DNase, trypsin, chymotrypsin, and phospholipase C, and to a detergent, deoxycholate. The use of these enzymes and deoxycholate, in combination with discontinuous and linear sucrose gradients, produced very pure preparations of free virions. Occluded virions were released by dissolving polyhedra in 0.05 M Na2CO3 – 0.04 M NaCl for 60 min at room temperature. The composition of the virion was estimated to be about 28% RNA and 72%protein.

Susceptibility of larvae of Hemerocampa leucostigma to several varieties of crystalliferous bacteria

Twelve isolates belonging to six H-antigen serotypes were evaluated for their effectiveness against Hemerocampa leucostigma larvae. All except one, Bacillus finitimus var. finitimus produced high levels of mortality in 4 days. In adition, we found no difference in susceptibility to Bacillus thuringiensis var. thuringiensis among first-through fifth-instar larvae.